Re: proposal: new polymorphic types - commontype and commontypearray

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От Tom Lane
Тема Re: proposal: new polymorphic types - commontype and commontypearray
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Msg-id 7166.1584579129@sss.pgh.pa.us
обсуждение исходный текст
Ответ на Re: proposal: new polymorphic types - commontype and commontypearray  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: proposal: new polymorphic types - commontype and commontypearray  (Tom Lane <tgl@sss.pgh.pa.us>)
Список pgsql-hackers
Here's a pretty-nearly-final version of the patch.

In 0001 below, I've left it throwing an error for the case of all
ANYCOMPATIBLE inputs being unknown, but the documentation fails to
acknowledge that.  0002 below is a delta patch that switches to the
other approach of resolving as TEXT.  I'm pretty well convinced that
0002 is what we should do, so I have not bothered to write a doc
change that would explain 0001's behavior on this point.

            regards, tom lane

diff --git a/doc/src/sgml/datatype.sgml b/doc/src/sgml/datatype.sgml
index 157fe4e..aa634ea 100644
--- a/doc/src/sgml/datatype.sgml
+++ b/doc/src/sgml/datatype.sgml
@@ -4789,6 +4789,22 @@ SELECT * FROM pg_attribute
    </indexterm>

    <indexterm zone="datatype-pseudo">
+    <primary>anycompatible</primary>
+   </indexterm>
+
+   <indexterm zone="datatype-pseudo">
+    <primary>anycompatiblearray</primary>
+   </indexterm>
+
+   <indexterm zone="datatype-pseudo">
+    <primary>anycompatiblenonarray</primary>
+   </indexterm>
+
+   <indexterm zone="datatype-pseudo">
+    <primary>anycompatiblerange</primary>
+   </indexterm>
+
+   <indexterm zone="datatype-pseudo">
     <primary>void</primary>
    </indexterm>

@@ -4894,6 +4910,35 @@ SELECT * FROM pg_attribute
        </row>

        <row>
+        <entry><type>anycompatible</type></entry>
+        <entry>Indicates that a function accepts any data type,
+        with automatic promotion of multiple arguments to a common data type
+        (see <xref linkend="extend-types-polymorphic"/>).</entry>
+       </row>
+
+       <row>
+        <entry><type>anycompatiblearray</type></entry>
+        <entry>Indicates that a function accepts any array data type,
+        with automatic promotion of multiple arguments to a common data type
+        (see <xref linkend="extend-types-polymorphic"/>).</entry>
+       </row>
+
+       <row>
+        <entry><type>anycompatiblenonarray</type></entry>
+        <entry>Indicates that a function accepts any non-array data type,
+        with automatic promotion of multiple arguments to a common data type
+        (see <xref linkend="extend-types-polymorphic"/>).</entry>
+       </row>
+
+       <row>
+        <entry><type>anycompatiblerange</type></entry>
+        <entry>Indicates that a function accepts any range data type,
+        with automatic promotion of multiple arguments to a common data type
+        (see <xref linkend="extend-types-polymorphic"/> and
+        <xref linkend="rangetypes"/>).</entry>
+       </row>
+
+       <row>
         <entry><type>cstring</type></entry>
         <entry>Indicates that a function accepts or returns a null-terminated C string.</entry>
        </row>
@@ -4960,7 +5005,7 @@ SELECT * FROM pg_attribute

    <para>
     Functions coded in C (whether built-in or dynamically loaded) can be
-    declared to accept or return any of these pseudo data types.  It is up to
+    declared to accept or return any of these pseudo-types.  It is up to
     the function author to ensure that the function will behave safely
     when a pseudo-type is used as an argument type.
    </para>
@@ -4971,10 +5016,9 @@ SELECT * FROM pg_attribute
     languages forbid use of a pseudo-type as an argument type, and allow
     only <type>void</type> and <type>record</type> as a result type (plus
     <type>trigger</type> or <type>event_trigger</type> when the function is used
-    as a trigger or event trigger).  Some also
-    support polymorphic functions using the types <type>anyelement</type>,
-    <type>anyarray</type>, <type>anynonarray</type>, <type>anyenum</type>, and
-    <type>anyrange</type>.
+    as a trigger or event trigger).  Some also support polymorphic functions
+    using the polymorphic pseudo-types, which are shown above and discussed
+    in detail in <xref linkend="extend-types-polymorphic"/>.
    </para>

    <para>
diff --git a/doc/src/sgml/extend.sgml b/doc/src/sgml/extend.sgml
index 97706da..930aeb7 100644
--- a/doc/src/sgml/extend.sgml
+++ b/doc/src/sgml/extend.sgml
@@ -229,21 +229,114 @@
    </indexterm>

     <para>
-     Five pseudo-types of special interest are <type>anyelement</type>,
-     <type>anyarray</type>, <type>anynonarray</type>, <type>anyenum</type>,
-     and <type>anyrange</type>,
-     which are collectively called <firstterm>polymorphic types</firstterm>.
-     Any function declared using these types is said to be
-     a <firstterm>polymorphic function</firstterm>.  A polymorphic function can
-     operate on many different data types, with the specific data type(s)
-     being determined by the data types actually passed to it in a particular
-     call.
+     Some pseudo-types of special interest are the <firstterm>polymorphic
+     types</firstterm>, which are used to declare <firstterm>polymorphic
+     functions</firstterm>.  This powerful feature allows a single function
+     definition to operate on many different data types, with the specific
+     data type(s) being determined by the data types actually passed to it
+     in a particular call.  The polymorphic types are shown in
+     <xref linkend="extend-types-polymorphic-table"/>.  Some examples of
+     their use appear in <xref linkend="xfunc-sql-polymorphic-functions"/>.
     </para>

+    <table id="extend-types-polymorphic-table">
+     <title>Polymorphic Types</title>
+     <tgroup cols="3">
+      <thead>
+       <row>
+        <entry>Name</entry>
+        <entry>Family</entry>
+        <entry>Description</entry>
+       </row>
+      </thead>
+
+      <tbody>
+       <row>
+        <entry><type>anyelement</type></entry>
+        <entry>Simple</entry>
+        <entry>Indicates that a function accepts any data type</entry>
+       </row>
+
+       <row>
+        <entry><type>anyarray</type></entry>
+        <entry>Simple</entry>
+        <entry>Indicates that a function accepts any array data type</entry>
+       </row>
+
+       <row>
+        <entry><type>anynonarray</type></entry>
+        <entry>Simple</entry>
+        <entry>Indicates that a function accepts any non-array data type</entry>
+       </row>
+
+       <row>
+        <entry><type>anyenum</type></entry>
+        <entry>Simple</entry>
+        <entry>Indicates that a function accepts any enum data type
+        (see <xref linkend="datatype-enum"/>)
+        </entry>
+       </row>
+
+       <row>
+        <entry><type>anyrange</type></entry>
+        <entry>Simple</entry>
+        <entry>Indicates that a function accepts any range data type
+        (see <xref linkend="rangetypes"/>)
+        </entry>
+       </row>
+
+       <row>
+        <entry><type>anycompatible</type></entry>
+        <entry>Common</entry>
+        <entry>Indicates that a function accepts any data type,
+        with automatic promotion of multiple arguments to a common data type
+        </entry>
+       </row>
+
+       <row>
+        <entry><type>anycompatiblearray</type></entry>
+        <entry>Common</entry>
+        <entry>Indicates that a function accepts any array data type,
+        with automatic promotion of multiple arguments to a common data type
+        </entry>
+       </row>
+
+       <row>
+        <entry><type>anycompatiblenonarray</type></entry>
+        <entry>Common</entry>
+        <entry>Indicates that a function accepts any non-array data type,
+        with automatic promotion of multiple arguments to a common data type
+        </entry>
+       </row>
+
+       <row>
+        <entry><type>anycompatiblerange</type></entry>
+        <entry>Common</entry>
+        <entry>Indicates that a function accepts any range data type,
+        with automatic promotion of multiple arguments to a common data type
+        </entry>
+       </row>
+      </tbody>
+     </tgroup>
+    </table>
+
     <para>
      Polymorphic arguments and results are tied to each other and are resolved
-     to a specific data type when a query calling a polymorphic function is
-     parsed.  Each position (either argument or return value) declared as
+     to specific data types when a query calling a polymorphic function is
+     parsed.  When there is more than one polymorphic argument, the actual
+     data types of the input values must match up as described below.  If the
+     function's result type is polymorphic, or it has output parameters of
+     polymorphic types, the types of those results are deduced from the
+     actual types of the polymorphic inputs as described below.
+    </para>
+
+    <para>
+     For the <quote>simple</quote> family of polymorphic types, the
+     matching and deduction rules work like this:
+    </para>
+
+    <para>
+     Each position (either argument or return value) declared as
      <type>anyelement</type> is allowed to have any specific actual
      data type, but in any given call they must all be the
      <emphasis>same</emphasis> actual type. Each
@@ -280,7 +373,8 @@
     <para>
      When the return value of a function is declared as a polymorphic type,
      there must be at least one argument position that is also polymorphic,
-     and the actual data type supplied as the argument determines the actual
+     and the actual data type(s) supplied for the polymorphic arguments
+     determine the actual
      result type for that call.  For example, if there were not already
      an array subscripting mechanism, one could define a function that
      implements subscripting as <literal>subscript(anyarray, integer)
@@ -294,8 +388,9 @@
     <para>
      In most cases, the parser can infer the actual data type for a
      polymorphic result type from arguments that are of a different
-     polymorphic type; for example <type>anyarray</type> can be deduced
-     from <type>anyelement</type> or vice versa.  The exception is that a
+     polymorphic type in the same family; for example <type>anyarray</type>
+     can be deduced from <type>anyelement</type> or vice versa.
+     An exception is that a
      polymorphic result of type <type>anyrange</type> requires an argument
      of type <type>anyrange</type>; it cannot be deduced
      from <type>anyarray</type> or <type>anyelement</type> arguments.  This
@@ -312,13 +407,69 @@
     </para>

     <para>
+     For the <quote>common</quote> family of polymorphic types, the
+     matching and deduction rules work approximately the same as for
+     the <quote>simple</quote> family, with one major difference: the
+     actual types of the arguments need not be identical, so long as they
+     can be implicitly cast to a single common type.  The common type is
+     selected following the same rules as for <literal>UNION</literal> and
+     related constructs (see <xref linkend="typeconv-union-case"/>).
+     Selection of the common type considers the actual types
+     of <type>anycompatible</type> and <type>anycompatiblenonarray</type>
+     inputs, the array element types of <type>anycompatiblearray</type>
+     inputs, and the range subtypes of <type>anycompatiblerange</type>
+     inputs.  If <type>anycompatiblenonarray</type> is present then the
+     common type is required to be a non-array type.  Once a common type is
+     identified, arguments in <type>anycompatible</type>
+     and <type>anycompatiblenonarray</type> positions are automatically
+     cast to that type, and arguments in <type>anycompatiblearray</type>
+     positions are automatically cast to the array type for that type.
+    </para>
+
+    <para>
+     Since there is no way to select a range type knowing only its subtype,
+     use of <type>anycompatiblerange</type> requires that all arguments
+     declared with that type have the same actual range type, and that that
+     type's subtype agree with the selected common type, so that no casting
+     of the range values is required.  As with <type>anyrange</type>, use
+     of <type>anycompatiblerange</type> as a function result type requires
+     that there be an <type>anycompatiblerange</type> argument.
+    </para>
+
+    <para>
+     Notice that there is no <type>anycompatibleenum</type> type.  Such a
+     type would not be very useful, since there normally are not any
+     implicit casts to enum types, meaning that there would be no way to
+     resolve a common type for dissimilar enum inputs.
+    </para>
+
+    <para>
+     The <quote>simple</quote> and <quote>common</quote> polymorphic
+     families represent two independent sets of type variables.  Consider
+     for example
+<programlisting>
+CREATE FUNCTION myfunc(a anyelement, b anyelement,
+                       c anycompatible, d anycompatible)
+RETURNS anycompatible AS ...
+</programlisting>
+     In an actual call of this function, the first two inputs must have
+     exactly the same type.  The last two inputs must be promotable to a
+     common type, but this type need not have anything to do with the type
+     of the first two inputs.  The result will have the common type of the
+     last two inputs.
+    </para>
+
+    <para>
      A variadic function (one taking a variable number of arguments, as in
      <xref linkend="xfunc-sql-variadic-functions"/>) can be
      polymorphic: this is accomplished by declaring its last parameter as
-     <literal>VARIADIC</literal> <type>anyarray</type>.  For purposes of argument
+     <literal>VARIADIC</literal> <type>anyarray</type> or
+     <literal>VARIADIC</literal> <type>anycompatiblearray</type>.
+     For purposes of argument
      matching and determining the actual result type, such a function behaves
      the same as if you had written the appropriate number of
-     <type>anynonarray</type> parameters.
+     <type>anynonarray</type> or <type>anycompatiblenonarray</type>
+     parameters.
     </para>
    </sect2>
   </sect1>
diff --git a/doc/src/sgml/plpgsql.sgml b/doc/src/sgml/plpgsql.sgml
index 2987a55..cc99aca 100644
--- a/doc/src/sgml/plpgsql.sgml
+++ b/doc/src/sgml/plpgsql.sgml
@@ -138,13 +138,11 @@
     </para>

     <para>
-     <application>PL/pgSQL</application> functions can also be declared to accept
-     and return the polymorphic types
-     <type>anyelement</type>, <type>anyarray</type>, <type>anynonarray</type>,
-     <type>anyenum</type>, and <type>anyrange</type>.  The actual
-     data types handled by a polymorphic function can vary from call to
-     call, as discussed in <xref linkend="extend-types-polymorphic"/>.
-     An example is shown in <xref linkend="plpgsql-declaration-parameters"/>.
+     <application>PL/pgSQL</application> functions can also be declared to
+     accept and return the polymorphic types described in
+     <xref linkend="extend-types-polymorphic"/>, thus allowing the actual data
+     types handled by the function to vary from call to call.
+     Examples appear in <xref linkend="plpgsql-declaration-parameters"/>.
     </para>

     <para>
@@ -519,13 +517,11 @@ $$ LANGUAGE plpgsql;
      </para>

      <para>
-      When the return type of a <application>PL/pgSQL</application>
-      function is declared as a polymorphic type (<type>anyelement</type>,
-      <type>anyarray</type>, <type>anynonarray</type>, <type>anyenum</type>,
-      or <type>anyrange</type>), a special parameter <literal>$0</literal>
-      is created.  Its data type is the actual return type of the function,
-      as deduced from the actual input types (see <xref
-      linkend="extend-types-polymorphic"/>).
+      When the return type of a <application>PL/pgSQL</application> function
+      is declared as a polymorphic type (see
+      <xref linkend="extend-types-polymorphic"/>), a special
+      parameter <literal>$0</literal> is created.  Its data type is the actual
+      return type of the function, as deduced from the actual input types.
       This allows the function to access its actual return type
       as shown in <xref linkend="plpgsql-declaration-type"/>.
       <literal>$0</literal> is initialized to null and can be modified by
@@ -563,6 +559,32 @@ END;
 $$ LANGUAGE plpgsql;
 </programlisting>
      </para>
+
+     <para>
+      In practice it might be more useful to declare a polymorphic function
+      using the <type>anycompatible</type> family of types, so that automatic
+      promotion of the input arguments to a common type will occur.
+      For example:
+
+<programlisting>
+CREATE FUNCTION add_three_values(v1 anycompatible, v2 anycompatible, v3 anycompatible)
+RETURNS anycompatible AS $$
+BEGIN
+    RETURN v1 + v2 + v3;
+END;
+$$ LANGUAGE plpgsql;
+</programlisting>
+
+      With this example, a call such as
+
+<programlisting>
+SELECT add_three_values(1, 2, 4.7);
+</programlisting>
+
+      will work, automatically promoting the integer inputs to numeric.
+      The function using <type>anyelement</type> would require you to
+      cast the three inputs to the same type manually.
+     </para>
     </sect2>

   <sect2 id="plpgsql-declaration-alias">
diff --git a/doc/src/sgml/xfunc.sgml b/doc/src/sgml/xfunc.sgml
index 6350f92..ff51660 100644
--- a/doc/src/sgml/xfunc.sgml
+++ b/doc/src/sgml/xfunc.sgml
@@ -1226,16 +1226,13 @@ $$ LANGUAGE SQL;
     </para>
    </sect2>

-   <sect2>
+   <sect2 id="xfunc-sql-polymorphic-functions">
     <title>Polymorphic <acronym>SQL</acronym> Functions</title>

     <para>
      <acronym>SQL</acronym> functions can be declared to accept and
-     return the polymorphic types <type>anyelement</type>,
-     <type>anyarray</type>, <type>anynonarray</type>,
-     <type>anyenum</type>, and <type>anyrange</type>.  See <xref
-     linkend="extend-types-polymorphic"/> for a more detailed
-     explanation of polymorphic functions. Here is a polymorphic
+     return the polymorphic types described in <xref
+     linkend="extend-types-polymorphic"/>.  Here is a polymorphic
      function <function>make_array</function> that builds up an array
      from two arbitrary data type elements:
 <screen>
@@ -1260,9 +1257,33 @@ SELECT make_array(1, 2) AS intarray, make_array('a'::text, 'b') AS textarray;
      type.
      Without the typecast, you will get errors like this:
 <screen>
-<computeroutput>
 ERROR:  could not determine polymorphic type because input has type unknown
-</computeroutput>
+</screen>
+    </para>
+
+    <para>
+     With <function>make_array</function> declared as above, you must
+     provide two arguments that are of exactly the same data type; the
+     system will not attempt to resolve any type differences.  Thus for
+     example this does not work:
+<screen>
+SELECT make_array(1, 2.5) AS numericarray;
+ERROR:  function make_array(integer, numeric) does not exist
+</screen>
+     An alternative approach is to use the <quote>common</quote> family of
+     polymorphic types, which allows the system to try to identify a
+     suitable common type:
+<screen>
+CREATE FUNCTION make_array2(anycompatible, anycompatible)
+RETURNS anycompatiblearray AS $$
+    SELECT ARRAY[$1, $2];
+$$ LANGUAGE SQL;
+
+SELECT make_array2(1, 2.5) AS numericarray;
+ numericarray
+--------------
+ {1,2.5}
+(1 row)
 </screen>
     </para>

@@ -1284,7 +1305,7 @@ CREATE FUNCTION invalid_func() RETURNS anyelement AS $$
     SELECT 1;
 $$ LANGUAGE SQL;
 ERROR:  cannot determine result data type
-DETAIL:  A function returning a polymorphic type must have at least one polymorphic argument.
+DETAIL:  A result of type anyelement requires at least one input of type anyelement, anyarray, anynonarray, anyenum,
oranyrange. 
 </screen>
     </para>

@@ -3157,11 +3178,9 @@ CREATE OR REPLACE FUNCTION retcomposite(IN integer, IN integer,

     <para>
      C-language functions can be declared to accept and
-     return the polymorphic types
-     <type>anyelement</type>, <type>anyarray</type>, <type>anynonarray</type>,
-     <type>anyenum</type>, and <type>anyrange</type>.
-     See <xref linkend="extend-types-polymorphic"/> for a more detailed explanation
-     of polymorphic functions. When function arguments or return types
+     return the polymorphic types described in <xref
+     linkend="extend-types-polymorphic"/>.
+     When a function's arguments or return types
      are defined as polymorphic types, the function author cannot know
      in advance what data type it will be called with, or
      need to return. There are two routines provided in <filename>fmgr.h</filename>
diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 76fd938..22540bb 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -404,10 +404,6 @@ ConstructTupleDescriptor(Relation heapRelation,
          */
         keyType = amroutine->amkeytype;

-        /*
-         * Code below is concerned to the opclasses which are not used with
-         * the included columns.
-         */
         if (i < indexInfo->ii_NumIndexKeyAttrs)
         {
             tuple = SearchSysCache1(CLAOID, ObjectIdGetDatum(classObjectId[i]));
@@ -422,6 +418,10 @@ ConstructTupleDescriptor(Relation heapRelation,
              * If keytype is specified as ANYELEMENT, and opcintype is
              * ANYARRAY, then the attribute type must be an array (else it'd
              * not have matched this opclass); use its element type.
+             *
+             * We could also allow ANYCOMPATIBLE/ANYCOMPATIBLEARRAY here, but
+             * there seems no need to do so; there's no reason to declare an
+             * opclass as taking ANYCOMPATIBLEARRAY rather than ANYARRAY.
              */
             if (keyType == ANYELEMENTOID && opclassTup->opcintype == ANYARRAYOID)
             {
diff --git a/src/backend/catalog/pg_proc.c b/src/backend/catalog/pg_proc.c
index 0cac936..6cdda35 100644
--- a/src/backend/catalog/pg_proc.c
+++ b/src/backend/catalog/pg_proc.c
@@ -262,6 +262,9 @@ ProcedureCreate(const char *procedureName,
                         case ANYARRAYOID:
                             variadicType = ANYELEMENTOID;
                             break;
+                        case ANYCOMPATIBLEARRAYOID:
+                            variadicType = ANYCOMPATIBLEOID;
+                            break;
                         default:
                             variadicType = get_element_type(allParams[i]);
                             if (!OidIsValid(variadicType))
diff --git a/src/backend/commands/functioncmds.c b/src/backend/commands/functioncmds.c
index 5eac55a..694114a 100644
--- a/src/backend/commands/functioncmds.c
+++ b/src/backend/commands/functioncmds.c
@@ -320,6 +320,7 @@ interpret_function_parameter_list(ParseState *pstate,
             switch (toid)
             {
                 case ANYARRAYOID:
+                case ANYCOMPATIBLEARRAYOID:
                 case ANYOID:
                     /* okay */
                     break;
diff --git a/src/backend/parser/parse_coerce.c b/src/backend/parser/parse_coerce.c
index c3fb51d..1e53f7c 100644
--- a/src/backend/parser/parse_coerce.c
+++ b/src/backend/parser/parse_coerce.c
@@ -167,15 +167,17 @@ coerce_type(ParseState *pstate, Node *node,
     }
     if (targetTypeId == ANYOID ||
         targetTypeId == ANYELEMENTOID ||
-        targetTypeId == ANYNONARRAYOID)
+        targetTypeId == ANYNONARRAYOID ||
+        targetTypeId == ANYCOMPATIBLEOID ||
+        targetTypeId == ANYCOMPATIBLENONARRAYOID)
     {
         /*
          * Assume can_coerce_type verified that implicit coercion is okay.
          *
          * Note: by returning the unmodified node here, we are saying that
          * it's OK to treat an UNKNOWN constant as a valid input for a
-         * function accepting ANY, ANYELEMENT, or ANYNONARRAY.  This should be
-         * all right, since an UNKNOWN value is still a perfectly valid Datum.
+         * function accepting one of these pseudotypes.  This should be all
+         * right, since an UNKNOWN value is still a perfectly valid Datum.
          *
          * NB: we do NOT want a RelabelType here: the exposed type of the
          * function argument must be its actual type, not the polymorphic
@@ -185,7 +187,9 @@ coerce_type(ParseState *pstate, Node *node,
     }
     if (targetTypeId == ANYARRAYOID ||
         targetTypeId == ANYENUMOID ||
-        targetTypeId == ANYRANGEOID)
+        targetTypeId == ANYRANGEOID ||
+        targetTypeId == ANYCOMPATIBLEARRAYOID ||
+        targetTypeId == ANYCOMPATIBLERANGEOID)
     {
         /*
          * Assume can_coerce_type verified that implicit coercion is okay.
@@ -193,10 +197,10 @@ coerce_type(ParseState *pstate, Node *node,
          * These cases are unlike the ones above because the exposed type of
          * the argument must be an actual array, enum, or range type.  In
          * particular the argument must *not* be an UNKNOWN constant.  If it
-         * is, we just fall through; below, we'll call anyarray_in,
-         * anyenum_in, or anyrange_in, which will produce an error.  Also, if
-         * what we have is a domain over array, enum, or range, we have to
-         * relabel it to its base type.
+         * is, we just fall through; below, we'll call the pseudotype's input
+         * function, which will produce an error.  Also, if what we have is a
+         * domain over array, enum, or range, we have to relabel it to its
+         * base type.
          *
          * Note: currently, we can't actually see a domain-over-enum here,
          * since the other functions in this file will not match such a
@@ -1387,6 +1391,103 @@ select_common_type(ParseState *pstate, List *exprs, const char *context,
 }

 /*
+ * select_common_type_from_oids()
+ *        Determine the common supertype of an array of type OIDs.
+ *
+ * This is the same logic as select_common_type(), but working from
+ * an array of type OIDs not a list of expressions.  As in that function,
+ * earlier entries in the array have some preference over later ones.
+ * On failure, return InvalidOid if noerror is true, else throw an error.
+ *
+ * Note: neither caller will pass any UNKNOWNOID entries, so the tests
+ * for that in this function are dead code.  However, they don't cost much,
+ * and it seems better to keep this logic as close to select_common_type()
+ * as possible.
+ */
+static Oid
+select_common_type_from_oids(int nargs, const Oid *typeids, bool noerror)
+{
+    Oid            ptype;
+    TYPCATEGORY pcategory;
+    bool        pispreferred;
+    int            i = 1;
+
+    Assert(nargs > 0);
+    ptype = typeids[0];
+
+    /* If all input types are valid and exactly the same, pick that type. */
+    if (ptype != UNKNOWNOID)
+    {
+        for (; i < nargs; i++)
+        {
+            if (typeids[i] != ptype)
+                break;
+        }
+        if (i == nargs)
+            return ptype;
+    }
+
+    /*
+     * Nope, so set up for the full algorithm.  Note that at this point, we
+     * can skip array entries before "i"; they are all equal to ptype.
+     */
+    ptype = getBaseType(ptype);
+    get_type_category_preferred(ptype, &pcategory, &pispreferred);
+
+    for (; i < nargs; i++)
+    {
+        Oid            ntype = getBaseType(typeids[i]);
+
+        /* move on to next one if no new information... */
+        if (ntype != UNKNOWNOID && ntype != ptype)
+        {
+            TYPCATEGORY ncategory;
+            bool        nispreferred;
+
+            get_type_category_preferred(ntype, &ncategory, &nispreferred);
+            if (ptype == UNKNOWNOID)
+            {
+                /* so far, only unknowns so take anything... */
+                ptype = ntype;
+                pcategory = ncategory;
+                pispreferred = nispreferred;
+            }
+            else if (ncategory != pcategory)
+            {
+                /*
+                 * both types in different categories? then not much hope...
+                 */
+                if (noerror)
+                    return InvalidOid;
+                ereport(ERROR,
+                        (errcode(ERRCODE_DATATYPE_MISMATCH),
+                         errmsg("argument types %s and %s cannot be matched",
+                                format_type_be(ptype),
+                                format_type_be(ntype))));
+            }
+            else if (!pispreferred &&
+                     can_coerce_type(1, &ptype, &ntype, COERCION_IMPLICIT) &&
+                     !can_coerce_type(1, &ntype, &ptype, COERCION_IMPLICIT))
+            {
+                /*
+                 * take new type if can coerce to it implicitly but not the
+                 * other way; but if we have a preferred type, stay on it.
+                 */
+                ptype = ntype;
+                pcategory = ncategory;
+                pispreferred = nispreferred;
+            }
+        }
+    }
+
+    /* Like select_common_type(), choose TEXT if all inputs were UNKNOWN */
+    if (ptype == UNKNOWNOID)
+        ptype = TEXTOID;
+
+    return ptype;
+}
+
+/*
  * coerce_to_common_type()
  *        Coerce an expression to the given type.
  *
@@ -1442,14 +1543,28 @@ coerce_to_common_type(ParseState *pstate, Node *node,
  *      we add the extra condition that the ANYELEMENT type must not be an array.
  *      (This is a no-op if used in combination with ANYARRAY or ANYENUM, but
  *      is an extra restriction if not.)
+ * 7) All arguments declared ANYCOMPATIBLE must be implicitly castable
+ *      to a common supertype (chosen as per select_common_type's rules).
+ *      ANYCOMPATIBLENONARRAY works like ANYCOMPATIBLE but also requires the
+ *      common supertype to not be an array.  If there are ANYCOMPATIBLEARRAY
+ *      or ANYCOMPATIBLERANGE arguments, their element types or subtypes are
+ *      included while making the choice of common supertype.
+ * 8) The resolved type of ANYCOMPATIBLEARRAY arguments will be the array
+ *      type over the common supertype (which might not be the same array type
+ *      as any of the original arrays).
+ * 9) All ANYCOMPATIBLERANGE arguments must be the exact same range type
+ *      (after domain flattening), since we have no preference rule that would
+ *      let us choose one over another.  Furthermore, that range's subtype
+ *      must exactly match the common supertype chosen by rule 7.
  *
  * Domains over arrays match ANYARRAY, and are immediately flattened to their
  * base type.  (Thus, for example, we will consider it a match if one ANYARRAY
  * argument is a domain over int4[] while another one is just int4[].)    Also
- * notice that such a domain does *not* match ANYNONARRAY.
+ * notice that such a domain does *not* match ANYNONARRAY.  The same goes
+ * for ANYCOMPATIBLEARRAY and ANYCOMPATIBLENONARRAY.
  *
- * Similarly, domains over ranges match ANYRANGE, and are immediately
- * flattened to their base type.
+ * Similarly, domains over ranges match ANYRANGE or ANYCOMPATIBLERANGE,
+ * and are immediately flattened to their base type.
  *
  * Note that domains aren't currently considered to match ANYENUM,
  * even if their base type would match.
@@ -1467,13 +1582,19 @@ check_generic_type_consistency(const Oid *actual_arg_types,
     Oid            elem_typeid = InvalidOid;
     Oid            array_typeid = InvalidOid;
     Oid            range_typeid = InvalidOid;
+    Oid            anycompatible_range_typeid = InvalidOid;
+    Oid            anycompatible_range_typelem = InvalidOid;
     bool        have_anynonarray = false;
     bool        have_anyenum = false;
+    bool        have_anycompatible_nonarray = false;
+    int            n_anycompatible_args = 0;
+    Oid            anycompatible_actual_types[FUNC_MAX_ARGS];

     /*
      * Loop through the arguments to see if we have any that are polymorphic.
      * If so, require the actual types to be consistent.
      */
+    Assert(nargs <= FUNC_MAX_ARGS);
     for (int j = 0; j < nargs; j++)
     {
         Oid            decl_type = declared_arg_types[j];
@@ -1511,6 +1632,50 @@ check_generic_type_consistency(const Oid *actual_arg_types,
                 return false;
             range_typeid = actual_type;
         }
+        else if (decl_type == ANYCOMPATIBLEOID ||
+                 decl_type == ANYCOMPATIBLENONARRAYOID)
+        {
+            if (decl_type == ANYCOMPATIBLENONARRAYOID)
+                have_anycompatible_nonarray = true;
+            if (actual_type == UNKNOWNOID)
+                continue;
+            /* collect the actual types of non-unknown COMPATIBLE args */
+            anycompatible_actual_types[n_anycompatible_args++] = actual_type;
+        }
+        else if (decl_type == ANYCOMPATIBLEARRAYOID)
+        {
+            Oid            elem_type;
+
+            if (actual_type == UNKNOWNOID)
+                continue;
+            actual_type = getBaseType(actual_type); /* flatten domains */
+            elem_type = get_element_type(actual_type);
+            if (!OidIsValid(elem_type))
+                return false;    /* not an array */
+            /* collect the element type for common-supertype choice */
+            anycompatible_actual_types[n_anycompatible_args++] = elem_type;
+        }
+        else if (decl_type == ANYCOMPATIBLERANGEOID)
+        {
+            if (actual_type == UNKNOWNOID)
+                continue;
+            actual_type = getBaseType(actual_type); /* flatten domains */
+            if (OidIsValid(anycompatible_range_typeid))
+            {
+                /* All ANYCOMPATIBLERANGE arguments must be the same type */
+                if (anycompatible_range_typeid != actual_type)
+                    return false;
+            }
+            else
+            {
+                anycompatible_range_typeid = actual_type;
+                anycompatible_range_typelem = get_range_subtype(actual_type);
+                if (!OidIsValid(anycompatible_range_typelem))
+                    return false;    /* not a range type */
+                /* collect the subtype for common-supertype choice */
+                anycompatible_actual_types[n_anycompatible_args++] = anycompatible_range_typelem;
+            }
+        }
     }

     /* Get the element type based on the array type, if we have one */
@@ -1591,6 +1756,38 @@ check_generic_type_consistency(const Oid *actual_arg_types,
             return false;
     }

+    /* Check matching of ANYCOMPATIBLE-family arguments, if any */
+    if (n_anycompatible_args > 0)
+    {
+        Oid            anycompatible_typeid;
+
+        anycompatible_typeid =
+            select_common_type_from_oids(n_anycompatible_args,
+                                         anycompatible_actual_types,
+                                         true);
+
+        if (!OidIsValid(anycompatible_typeid))
+            return false;        /* there's no common supertype */
+
+        if (have_anycompatible_nonarray)
+        {
+            /*
+             * require the anycompatible type to not be an array or domain
+             * over array
+             */
+            if (type_is_array_domain(anycompatible_typeid))
+                return false;
+        }
+
+        /*
+         * the anycompatible type must exactly match the range element type,
+         * if we were able to identify one
+         */
+        if (OidIsValid(anycompatible_range_typelem) &&
+            anycompatible_range_typelem != anycompatible_typeid)
+            return false;
+    }
+
     /* Looks valid */
     return true;
 }
@@ -1610,6 +1807,11 @@ check_generic_type_consistency(const Oid *actual_arg_types,
  * successful, we alter that position of declared_arg_types[] so that
  * make_fn_arguments will coerce the literal to the right thing.
  *
+ * If we have polymorphic arguments of the ANYCOMPATIBLE family,
+ * we similarly alter declared_arg_types[] entries to show the resolved
+ * common supertype, so that make_fn_arguments will coerce the actual
+ * arguments to the proper type.
+ *
  * Rules are applied to the function's return type (possibly altering it)
  * if it is declared as a polymorphic type:
  *
@@ -1631,11 +1833,20 @@ check_generic_type_consistency(const Oid *actual_arg_types,
  *      we add the extra condition that the ANYELEMENT type must not be an array.
  *      (This is a no-op if used in combination with ANYARRAY or ANYENUM, but
  *      is an extra restriction if not.)
+ * 8) ANYCOMPATIBLE, ANYCOMPATIBLEARRAY, ANYCOMPATIBLENONARRAY, and
+ *      ANYCOMPATIBLERANGE are handled by resolving the common supertype
+ *      of those arguments (or their element types/subtypes, for array and range
+ *      inputs), and then coercing all those arguments to the common supertype,
+ *      or the array type over the common supertype for ANYCOMPATIBLEARRAY.
+ *      For ANYCOMPATIBLERANGE, there must be at least one non-UNKNOWN input,
+ *      all such inputs must be the same range type, and that type's subtype
+ *      must equal the common supertype.
  *
  * Domains over arrays or ranges match ANYARRAY or ANYRANGE arguments,
  * respectively, and are immediately flattened to their base type.  (In
  * particular, if the return type is also ANYARRAY or ANYRANGE, we'll set
- * it to the base type not the domain type.)
+ * it to the base type not the domain type.)  The same is true for
+ * ANYCOMPATIBLEARRAY and ANYCOMPATIBLERANGE.
  *
  * When allow_poly is false, we are not expecting any of the actual_arg_types
  * to be polymorphic, and we should not return a polymorphic result type
@@ -1652,7 +1863,12 @@ check_generic_type_consistency(const Oid *actual_arg_types,
  * the element type to infer the result type.  Note this means that functions
  * taking ANYARRAY had better behave sanely if applied to the pg_statistic
  * columns; they can't just assume that successive inputs are of the same
- * actual element type.
+ * actual element type.  There is no similar logic for ANYCOMPATIBLEARRAY;
+ * there isn't a need for it since there are no catalog columns of that type,
+ * so we won't see it as input.  We could consider matching an actual ANYARRAY
+ * input to an ANYCOMPATIBLEARRAY argument, but at present that seems useless
+ * as well, since there's no value in using ANYCOMPATIBLEARRAY unless there's
+ * at least one other ANYCOMPATIBLE-family argument or result.
  */
 Oid
 enforce_generic_type_consistency(const Oid *actual_arg_types,
@@ -1661,18 +1877,29 @@ enforce_generic_type_consistency(const Oid *actual_arg_types,
                                  Oid rettype,
                                  bool allow_poly)
 {
+    bool        have_poly_anycompatible = false;
     bool        have_poly_unknowns = false;
     Oid            elem_typeid = InvalidOid;
     Oid            array_typeid = InvalidOid;
     Oid            range_typeid = InvalidOid;
-    int            n_poly_args = 0;
+    Oid            anycompatible_typeid = InvalidOid;
+    Oid            anycompatible_array_typeid = InvalidOid;
+    Oid            anycompatible_range_typeid = InvalidOid;
+    Oid            anycompatible_range_typelem = InvalidOid;
     bool        have_anynonarray = (rettype == ANYNONARRAYOID);
     bool        have_anyenum = (rettype == ANYENUMOID);
+    bool        have_anycompatible_nonarray = (rettype == ANYCOMPATIBLENONARRAYOID);
+    bool        have_anycompatible_array = (rettype == ANYCOMPATIBLEARRAYOID);
+    bool        have_anycompatible_range = (rettype == ANYCOMPATIBLERANGEOID);
+    int            n_poly_args = 0;    /* this counts all family-1 arguments */
+    int            n_anycompatible_args = 0;    /* this counts only non-unknowns */
+    Oid            anycompatible_actual_types[FUNC_MAX_ARGS];

     /*
      * Loop through the arguments to see if we have any that are polymorphic.
      * If so, require the actual types to be consistent.
      */
+    Assert(nargs <= FUNC_MAX_ARGS);
     for (int j = 0; j < nargs; j++)
     {
         Oid            decl_type = declared_arg_types[j];
@@ -1743,18 +1970,87 @@ enforce_generic_type_consistency(const Oid *actual_arg_types,
                                    format_type_be(actual_type))));
             range_typeid = actual_type;
         }
+        else if (decl_type == ANYCOMPATIBLEOID ||
+                 decl_type == ANYCOMPATIBLENONARRAYOID)
+        {
+            have_poly_anycompatible = true;
+            if (decl_type == ANYCOMPATIBLENONARRAYOID)
+                have_anycompatible_nonarray = true;
+            if (actual_type == UNKNOWNOID)
+                continue;
+            if (allow_poly && decl_type == actual_type)
+                continue;        /* no new information here */
+            /* collect the actual types of non-unknown COMPATIBLE args */
+            anycompatible_actual_types[n_anycompatible_args++] = actual_type;
+        }
+        else if (decl_type == ANYCOMPATIBLEARRAYOID)
+        {
+            Oid            anycompatible_elem_type;
+
+            have_poly_anycompatible = true;
+            have_anycompatible_array = true;
+            if (actual_type == UNKNOWNOID)
+                continue;
+            if (allow_poly && decl_type == actual_type)
+                continue;        /* no new information here */
+            actual_type = getBaseType(actual_type); /* flatten domains */
+            anycompatible_elem_type = get_element_type(actual_type);
+            if (!OidIsValid(anycompatible_elem_type))
+                ereport(ERROR,
+                        (errcode(ERRCODE_DATATYPE_MISMATCH),
+                         errmsg("argument declared %s is not an array but type %s",
+                                "anycompatiblearray",
+                                format_type_be(actual_type))));
+            /* collect the element type for common-supertype choice */
+            anycompatible_actual_types[n_anycompatible_args++] = anycompatible_elem_type;
+        }
+        else if (decl_type == ANYCOMPATIBLERANGEOID)
+        {
+            have_poly_anycompatible = true;
+            have_anycompatible_range = true;
+            if (actual_type == UNKNOWNOID)
+                continue;
+            if (allow_poly && decl_type == actual_type)
+                continue;        /* no new information here */
+            actual_type = getBaseType(actual_type); /* flatten domains */
+            if (OidIsValid(anycompatible_range_typeid))
+            {
+                /* All ANYCOMPATIBLERANGE arguments must be the same type */
+                if (anycompatible_range_typeid != actual_type)
+                    ereport(ERROR,
+                            (errcode(ERRCODE_DATATYPE_MISMATCH),
+                             errmsg("arguments declared \"anycompatiblerange\" are not all alike"),
+                             errdetail("%s versus %s",
+                                       format_type_be(anycompatible_range_typeid),
+                                       format_type_be(actual_type))));
+            }
+            else
+            {
+                anycompatible_range_typeid = actual_type;
+                anycompatible_range_typelem = get_range_subtype(actual_type);
+                if (!OidIsValid(anycompatible_range_typelem))
+                    ereport(ERROR,
+                            (errcode(ERRCODE_DATATYPE_MISMATCH),
+                             errmsg("argument declared %s is not a range type but type %s",
+                                    "anycompatiblerange",
+                                    format_type_be(actual_type))));
+                /* collect the subtype for common-supertype choice */
+                anycompatible_actual_types[n_anycompatible_args++] = anycompatible_range_typelem;
+            }
+        }
     }

     /*
      * Fast Track: if none of the arguments are polymorphic, return the
      * unmodified rettype.  We assume it can't be polymorphic either.
      */
-    if (n_poly_args == 0)
+    if (n_poly_args == 0 && !have_poly_anycompatible)
     {
         Assert(!IsPolymorphicType(rettype));
         return rettype;
     }

+    /* Check matching of family-1 polymorphic arguments, if any */
     if (n_poly_args)
     {
         /* Get the element type based on the array type, if we have one */
@@ -1766,13 +2062,14 @@ enforce_generic_type_consistency(const Oid *actual_arg_types,
             {
                 /*
                  * Special case for matching ANYARRAY input to an ANYARRAY
-                 * argument: allow it iff no other arguments are polymorphic
-                 * (otherwise we couldn't be sure whether the array element
-                 * type matches up) and the result type doesn't require us to
-                 * infer a specific element type.
+                 * argument: allow it iff no other arguments are family-1
+                 * polymorphics (otherwise we couldn't be sure whether the
+                 * array element type matches up) and the result type doesn't
+                 * require us to infer a specific element type.
                  */
                 if (n_poly_args != 1 ||
-                    (rettype != ANYARRAYOID && IsPolymorphicType(rettype)))
+                    (rettype != ANYARRAYOID &&
+                     IsPolymorphicTypeFamily1(rettype)))
                     ereport(ERROR,
                             (errcode(ERRCODE_DATATYPE_MISMATCH),
                              errmsg("cannot determine element type of \"anyarray\" argument")));
@@ -1888,9 +2185,105 @@ enforce_generic_type_consistency(const Oid *actual_arg_types,
         }
     }

+    /* Check matching of family-2 polymorphic arguments, if any */
+    if (have_poly_anycompatible)
+    {
+        if (n_anycompatible_args > 0)
+        {
+            anycompatible_typeid =
+                select_common_type_from_oids(n_anycompatible_args,
+                                             anycompatible_actual_types,
+                                             false);
+
+            if (have_anycompatible_array)
+            {
+                anycompatible_array_typeid = get_array_type(anycompatible_typeid);
+                if (!OidIsValid(anycompatible_array_typeid))
+                    ereport(ERROR,
+                            (errcode(ERRCODE_UNDEFINED_OBJECT),
+                             errmsg("could not find array type for data type %s",
+                                    format_type_be(anycompatible_typeid))));
+            }
+
+            if (have_anycompatible_range)
+            {
+                /* we can't infer a range type from the others */
+                if (!OidIsValid(anycompatible_range_typeid))
+                    ereport(ERROR,
+                            (errcode(ERRCODE_DATATYPE_MISMATCH),
+                             errmsg("could not determine polymorphic type %s because input has type %s",
+                                    "anycompatiblerange", "unknown")));
+
+                /*
+                 * the anycompatible type must exactly match the range element
+                 * type
+                 */
+                if (anycompatible_range_typelem != anycompatible_typeid)
+                    ereport(ERROR,
+                            (errcode(ERRCODE_DATATYPE_MISMATCH),
+                             errmsg("anycompatiblerange type %s does not match anycompatible type %s",
+                                    format_type_be(anycompatible_range_typeid),
+                                    format_type_be(anycompatible_typeid))));
+            }
+
+            if (have_anycompatible_nonarray)
+            {
+                /*
+                 * require the element type to not be an array or domain over
+                 * array
+                 */
+                if (type_is_array_domain(anycompatible_typeid))
+                    ereport(ERROR,
+                            (errcode(ERRCODE_DATATYPE_MISMATCH),
+                             errmsg("type matched to anycompatiblenonarray is an array type: %s",
+                                    format_type_be(anycompatible_typeid))));
+            }
+        }
+        else
+        {
+            if (allow_poly)
+            {
+                anycompatible_typeid = ANYCOMPATIBLEOID;
+                anycompatible_array_typeid = ANYCOMPATIBLEARRAYOID;
+                anycompatible_range_typeid = ANYCOMPATIBLERANGEOID;
+            }
+            else
+            {
+                /*
+                 * Only way to get here is if all the ANYCOMPATIBLE args have
+                 * UNKNOWN inputs
+                 *
+                 * XXX shouldn't we use TEXT?  But not TEXTRANGE.
+                 */
+                ereport(ERROR,
+                        (errcode(ERRCODE_DATATYPE_MISMATCH),
+                         errmsg("could not determine polymorphic type because input has type %s",
+                                "unknown")));
+            }
+        }
+
+        /* replace polymorphic types by selected types */
+        for (int j = 0; j < nargs; j++)
+        {
+            Oid            decl_type = declared_arg_types[j];
+
+            if (decl_type == ANYCOMPATIBLEOID ||
+                decl_type == ANYCOMPATIBLENONARRAYOID)
+                declared_arg_types[j] = anycompatible_typeid;
+            else if (decl_type == ANYCOMPATIBLEARRAYOID)
+                declared_arg_types[j] = anycompatible_array_typeid;
+            else if (decl_type == ANYCOMPATIBLERANGEOID)
+                declared_arg_types[j] = anycompatible_range_typeid;
+        }
+    }
+
     /*
      * If we had any UNKNOWN inputs for polymorphic arguments, re-scan to
      * assign correct types to them.
+     *
+     * Note: we don't have to consider unknown inputs that were matched to
+     * ANYCOMPATIBLE-family arguments, because we forcibly updated their
+     * declared_arg_types[] positions just above.
      */
     if (have_poly_unknowns)
     {
@@ -1923,10 +2316,11 @@ enforce_generic_type_consistency(const Oid *actual_arg_types,
             {
                 if (!OidIsValid(range_typeid))
                 {
+                    /* we can't infer a range type from the others */
                     ereport(ERROR,
-                            (errcode(ERRCODE_UNDEFINED_OBJECT),
-                             errmsg("could not find range type for data type %s",
-                                    format_type_be(elem_typeid))));
+                            (errcode(ERRCODE_DATATYPE_MISMATCH),
+                             errmsg("could not determine polymorphic type %s because input has type %s",
+                                    "anyrange", "unknown")));
                 }
                 declared_arg_types[j] = range_typeid;
             }
@@ -1957,16 +2351,49 @@ enforce_generic_type_consistency(const Oid *actual_arg_types,
     /* if we return ANYRANGE use the appropriate argument type */
     if (rettype == ANYRANGEOID)
     {
+        /* this error is unreachable if the function signature is valid: */
         if (!OidIsValid(range_typeid))
-        {
             ereport(ERROR,
-                    (errcode(ERRCODE_UNDEFINED_OBJECT),
-                     errmsg("could not find range type for data type %s",
-                            format_type_be(elem_typeid))));
-        }
+                    (errcode(ERRCODE_DATATYPE_MISMATCH),
+                     errmsg("could not determine polymorphic type %s because input has type %s",
+                            "anyrange", "unknown")));
         return range_typeid;
     }

+    /* if we return ANYCOMPATIBLE use the appropriate type */
+    if (rettype == ANYCOMPATIBLEOID ||
+        rettype == ANYCOMPATIBLENONARRAYOID)
+    {
+        /* this error is unreachable if the function signature is valid: */
+        if (!OidIsValid(anycompatible_typeid))
+            ereport(ERROR,
+                    (errcode(ERRCODE_DATATYPE_MISMATCH),
+                     errmsg_internal("could not identify anycompatible type")));
+        return anycompatible_typeid;
+    }
+
+    /* if we return ANYCOMPATIBLEARRAY use the appropriate type */
+    if (rettype == ANYCOMPATIBLEARRAYOID)
+    {
+        /* this error is unreachable if the function signature is valid: */
+        if (!OidIsValid(anycompatible_array_typeid))
+            ereport(ERROR,
+                    (errcode(ERRCODE_DATATYPE_MISMATCH),
+                     errmsg_internal("could not identify anycompatiblearray type")));
+        return anycompatible_array_typeid;
+    }
+
+    /* if we return ANYCOMPATIBLERANGE use the appropriate argument type */
+    if (rettype == ANYCOMPATIBLERANGEOID)
+    {
+        /* this error is unreachable if the function signature is valid: */
+        if (!OidIsValid(anycompatible_range_typeid))
+            ereport(ERROR,
+                    (errcode(ERRCODE_DATATYPE_MISMATCH),
+                     errmsg_internal("could not identify anycompatiblerange type")));
+        return anycompatible_range_typeid;
+    }
+
     /* we don't return a generic type; send back the original return type */
     return rettype;
 }
@@ -1984,11 +2411,12 @@ check_valid_polymorphic_signature(Oid ret_type,
                                   const Oid *declared_arg_types,
                                   int nargs)
 {
-    if (ret_type == ANYRANGEOID)
+    if (ret_type == ANYRANGEOID || ret_type == ANYCOMPATIBLERANGEOID)
     {
         /*
          * ANYRANGE requires an ANYRANGE input, else we can't tell which of
-         * several range types with the same element type to use.
+         * several range types with the same element type to use.  Likewise
+         * for ANYCOMPATIBLERANGE.
          */
         for (int i = 0; i < nargs; i++)
         {
@@ -1998,17 +2426,30 @@ check_valid_polymorphic_signature(Oid ret_type,
         return psprintf(_("A result of type %s requires at least one input of type %s."),
                         format_type_be(ret_type), format_type_be(ret_type));
     }
-    else if (IsPolymorphicType(ret_type))
+    else if (IsPolymorphicTypeFamily1(ret_type))
     {
-        /* Otherwise, any polymorphic type can be deduced from any other */
+        /* Otherwise, any family-1 type can be deduced from any other */
         for (int i = 0; i < nargs; i++)
         {
-            if (IsPolymorphicType(declared_arg_types[i]))
+            if (IsPolymorphicTypeFamily1(declared_arg_types[i]))
                 return NULL;    /* OK */
         }
+        /* Keep this list in sync with IsPolymorphicTypeFamily1! */
         return psprintf(_("A result of type %s requires at least one input of type anyelement, anyarray, anynonarray,
anyenum,or anyrange."), 
                         format_type_be(ret_type));
     }
+    else if (IsPolymorphicTypeFamily2(ret_type))
+    {
+        /* Otherwise, any family-2 type can be deduced from any other */
+        for (int i = 0; i < nargs; i++)
+        {
+            if (IsPolymorphicTypeFamily2(declared_arg_types[i]))
+                return NULL;    /* OK */
+        }
+        /* Keep this list in sync with IsPolymorphicTypeFamily2! */
+        return psprintf(_("A result of type %s requires at least one input of type anycompatible, anycompatiblearray,
anycompatiblenonarray,or anycompatiblerange."), 
+                        format_type_be(ret_type));
+    }
     else
         return NULL;            /* OK, ret_type is not polymorphic */
 }
@@ -2113,8 +2554,9 @@ IsBinaryCoercible(Oid srctype, Oid targettype)
     if (srctype == targettype)
         return true;

-    /* Anything is coercible to ANY or ANYELEMENT */
-    if (targettype == ANYOID || targettype == ANYELEMENTOID)
+    /* Anything is coercible to ANY or ANYELEMENT or ANYCOMPATIBLE */
+    if (targettype == ANYOID || targettype == ANYELEMENTOID ||
+        targettype == ANYCOMPATIBLEOID)
         return true;

     /* If srctype is a domain, reduce to its base type */
@@ -2125,13 +2567,13 @@ IsBinaryCoercible(Oid srctype, Oid targettype)
     if (srctype == targettype)
         return true;

-    /* Also accept any array type as coercible to ANYARRAY */
-    if (targettype == ANYARRAYOID)
+    /* Also accept any array type as coercible to ANY[COMPATIBLE]ARRAY */
+    if (targettype == ANYARRAYOID || targettype == ANYCOMPATIBLEARRAYOID)
         if (type_is_array(srctype))
             return true;

-    /* Also accept any non-array type as coercible to ANYNONARRAY */
-    if (targettype == ANYNONARRAYOID)
+    /* Also accept any non-array type as coercible to ANY[COMPATIBLE]NONARRAY */
+    if (targettype == ANYNONARRAYOID || targettype == ANYCOMPATIBLENONARRAYOID)
         if (!type_is_array(srctype))
             return true;

@@ -2140,8 +2582,8 @@ IsBinaryCoercible(Oid srctype, Oid targettype)
         if (type_is_enum(srctype))
             return true;

-    /* Also accept any range type as coercible to ANYRANGE */
-    if (targettype == ANYRANGEOID)
+    /* Also accept any range type as coercible to ANY[COMPATIBLE]RANGE */
+    if (targettype == ANYRANGEOID || targettype == ANYCOMPATIBLERANGEOID)
         if (type_is_range(srctype))
             return true;

diff --git a/src/backend/utils/adt/json.c b/src/backend/utils/adt/json.c
index f78420e..8bb00ab 100644
--- a/src/backend/utils/adt/json.c
+++ b/src/backend/utils/adt/json.c
@@ -195,7 +195,7 @@ json_categorize_type(Oid typoid,
         default:
             /* Check for arrays and composites */
             if (OidIsValid(get_element_type(typoid)) || typoid == ANYARRAYOID
-                || typoid == RECORDARRAYOID)
+                || typoid == ANYCOMPATIBLEARRAYOID || typoid == RECORDARRAYOID)
                 *tcategory = JSONTYPE_ARRAY;
             else if (type_is_rowtype(typoid))    /* includes RECORDOID */
                 *tcategory = JSONTYPE_COMPOSITE;
diff --git a/src/backend/utils/adt/jsonb.c b/src/backend/utils/adt/jsonb.c
index b961d29..1e9ca04 100644
--- a/src/backend/utils/adt/jsonb.c
+++ b/src/backend/utils/adt/jsonb.c
@@ -677,7 +677,7 @@ jsonb_categorize_type(Oid typoid,
         default:
             /* Check for arrays and composites */
             if (OidIsValid(get_element_type(typoid)) || typoid == ANYARRAYOID
-                || typoid == RECORDARRAYOID)
+                || typoid == ANYCOMPATIBLEARRAYOID || typoid == RECORDARRAYOID)
                 *tcategory = JSONBTYPE_ARRAY;
             else if (type_is_rowtype(typoid))    /* includes RECORDOID */
                 *tcategory = JSONBTYPE_COMPOSITE;
diff --git a/src/backend/utils/adt/pseudotypes.c b/src/backend/utils/adt/pseudotypes.c
index 9eee03c..3d6b2f9 100644
--- a/src/backend/utils/adt/pseudotypes.c
+++ b/src/backend/utils/adt/pseudotypes.c
@@ -169,6 +169,26 @@ anyarray_send(PG_FUNCTION_ARGS)
 }

 /*
+ * anycompatiblearray
+ *
+ * We may as well allow output, since we do for anyarray.
+ */
+PSEUDOTYPE_DUMMY_INPUT_FUNC(anycompatiblearray);
+PSEUDOTYPE_DUMMY_RECEIVE_FUNC(anycompatiblearray);
+
+Datum
+anycompatiblearray_out(PG_FUNCTION_ARGS)
+{
+    return array_out(fcinfo);
+}
+
+Datum
+anycompatiblearray_send(PG_FUNCTION_ARGS)
+{
+    return array_send(fcinfo);
+}
+
+/*
  * anyenum
  *
  * We may as well allow output, since enum_out will in fact work.
@@ -195,6 +215,19 @@ anyrange_out(PG_FUNCTION_ARGS)
 }

 /*
+ * anycompatiblerange
+ *
+ * We may as well allow output, since range_out will in fact work.
+ */
+PSEUDOTYPE_DUMMY_INPUT_FUNC(anycompatiblerange);
+
+Datum
+anycompatiblerange_out(PG_FUNCTION_ARGS)
+{
+    return range_out(fcinfo);
+}
+
+/*
  * void
  *
  * We support void_in so that PL functions can return VOID without any
@@ -316,3 +349,5 @@ PSEUDOTYPE_DUMMY_IO_FUNCS(tsm_handler);
 PSEUDOTYPE_DUMMY_IO_FUNCS(internal);
 PSEUDOTYPE_DUMMY_IO_FUNCS(anyelement);
 PSEUDOTYPE_DUMMY_IO_FUNCS(anynonarray);
+PSEUDOTYPE_DUMMY_IO_FUNCS(anycompatible);
+PSEUDOTYPE_DUMMY_IO_FUNCS(anycompatiblenonarray);
diff --git a/src/backend/utils/fmgr/funcapi.c b/src/backend/utils/fmgr/funcapi.c
index 4e9d21b..78ed857 100644
--- a/src/backend/utils/fmgr/funcapi.c
+++ b/src/backend/utils/fmgr/funcapi.c
@@ -552,7 +552,9 @@ resolve_anyrange_from_others(polymorphic_actuals *actuals)
  * with concrete data types deduced from the input arguments.
  * declared_args is an oidvector of the function's declared input arg types
  * (showing which are polymorphic), and call_expr is the call expression.
- * Returns true if able to deduce all types, false if not.
+ *
+ * Returns true if able to deduce all types, false if necessary information
+ * is not provided (call_expr is NULL or arg types aren't identifiable).
  */
 static bool
 resolve_polymorphic_tupdesc(TupleDesc tupdesc, oidvector *declared_args,
@@ -564,8 +566,13 @@ resolve_polymorphic_tupdesc(TupleDesc tupdesc, oidvector *declared_args,
     bool        have_anyelement_result = false;
     bool        have_anyarray_result = false;
     bool        have_anyrange_result = false;
+    bool        have_anycompatible_result = false;
+    bool        have_anycompatible_array_result = false;
+    bool        have_anycompatible_range_result = false;
     polymorphic_actuals poly_actuals;
+    polymorphic_actuals anyc_actuals;
     Oid            anycollation = InvalidOid;
+    Oid            anycompatcollation = InvalidOid;
     int            i;

     /* See if there are any polymorphic outputs; quick out if not */
@@ -587,6 +594,19 @@ resolve_polymorphic_tupdesc(TupleDesc tupdesc, oidvector *declared_args,
                 have_polymorphic_result = true;
                 have_anyrange_result = true;
                 break;
+            case ANYCOMPATIBLEOID:
+            case ANYCOMPATIBLENONARRAYOID:
+                have_polymorphic_result = true;
+                have_anycompatible_result = true;
+                break;
+            case ANYCOMPATIBLEARRAYOID:
+                have_polymorphic_result = true;
+                have_anycompatible_array_result = true;
+                break;
+            case ANYCOMPATIBLERANGEOID:
+                have_polymorphic_result = true;
+                have_anycompatible_range_result = true;
+                break;
             default:
                 break;
         }
@@ -596,12 +616,16 @@ resolve_polymorphic_tupdesc(TupleDesc tupdesc, oidvector *declared_args,

     /*
      * Otherwise, extract actual datatype(s) from input arguments.  (We assume
-     * the parser already validated consistency of the arguments.)
+     * the parser already validated consistency of the arguments.  Also, for
+     * the ANYCOMPATIBLE pseudotype family, we expect that all matching
+     * arguments were coerced to the selected common supertype, so that it
+     * doesn't matter which one's exposed type we look at.)
      */
     if (!call_expr)
         return false;            /* no hope */

     memset(&poly_actuals, 0, sizeof(poly_actuals));
+    memset(&anyc_actuals, 0, sizeof(anyc_actuals));

     for (i = 0; i < nargs; i++)
     {
@@ -636,6 +660,34 @@ resolve_polymorphic_tupdesc(TupleDesc tupdesc, oidvector *declared_args,
                         return false;
                 }
                 break;
+            case ANYCOMPATIBLEOID:
+            case ANYCOMPATIBLENONARRAYOID:
+                if (!OidIsValid(anyc_actuals.anyelement_type))
+                {
+                    anyc_actuals.anyelement_type =
+                        get_call_expr_argtype(call_expr, i);
+                    if (!OidIsValid(anyc_actuals.anyelement_type))
+                        return false;
+                }
+                break;
+            case ANYCOMPATIBLEARRAYOID:
+                if (!OidIsValid(anyc_actuals.anyarray_type))
+                {
+                    anyc_actuals.anyarray_type =
+                        get_call_expr_argtype(call_expr, i);
+                    if (!OidIsValid(anyc_actuals.anyarray_type))
+                        return false;
+                }
+                break;
+            case ANYCOMPATIBLERANGEOID:
+                if (!OidIsValid(anyc_actuals.anyrange_type))
+                {
+                    anyc_actuals.anyrange_type =
+                        get_call_expr_argtype(call_expr, i);
+                    if (!OidIsValid(anyc_actuals.anyrange_type))
+                        return false;
+                }
+                break;
             default:
                 break;
         }
@@ -651,18 +703,33 @@ resolve_polymorphic_tupdesc(TupleDesc tupdesc, oidvector *declared_args,
     if (have_anyrange_result && !OidIsValid(poly_actuals.anyrange_type))
         resolve_anyrange_from_others(&poly_actuals);

+    if (have_anycompatible_result && !OidIsValid(anyc_actuals.anyelement_type))
+        resolve_anyelement_from_others(&anyc_actuals);
+
+    if (have_anycompatible_array_result && !OidIsValid(anyc_actuals.anyarray_type))
+        resolve_anyarray_from_others(&anyc_actuals);
+
+    if (have_anycompatible_range_result && !OidIsValid(anyc_actuals.anyrange_type))
+        resolve_anyrange_from_others(&anyc_actuals);
+
     /*
      * Identify the collation to use for polymorphic OUT parameters. (It'll
-     * necessarily be the same for both anyelement and anyarray.)  Note that
-     * range types are not collatable, so any possible internal collation of a
-     * range type is not considered here.
+     * necessarily be the same for both anyelement and anyarray, likewise for
+     * anycompatible and anycompatiblearray.)  Note that range types are not
+     * collatable, so any possible internal collation of a range type is not
+     * considered here.
      */
     if (OidIsValid(poly_actuals.anyelement_type))
         anycollation = get_typcollation(poly_actuals.anyelement_type);
     else if (OidIsValid(poly_actuals.anyarray_type))
         anycollation = get_typcollation(poly_actuals.anyarray_type);

-    if (OidIsValid(anycollation))
+    if (OidIsValid(anyc_actuals.anyelement_type))
+        anycompatcollation = get_typcollation(anyc_actuals.anyelement_type);
+    else if (OidIsValid(anyc_actuals.anyarray_type))
+        anycompatcollation = get_typcollation(anyc_actuals.anyarray_type);
+
+    if (OidIsValid(anycollation) || OidIsValid(anycompatcollation))
     {
         /*
          * The types are collatable, so consider whether to use a nondefault
@@ -672,7 +739,12 @@ resolve_polymorphic_tupdesc(TupleDesc tupdesc, oidvector *declared_args,
         Oid            inputcollation = exprInputCollation(call_expr);

         if (OidIsValid(inputcollation))
-            anycollation = inputcollation;
+        {
+            if (OidIsValid(anycollation))
+                anycollation = inputcollation;
+            if (OidIsValid(anycompatcollation))
+                anycompatcollation = inputcollation;
+        }
     }

     /* And finally replace the tuple column types as needed */
@@ -708,6 +780,31 @@ resolve_polymorphic_tupdesc(TupleDesc tupdesc, oidvector *declared_args,
                                    0);
                 /* no collation should be attached to a range type */
                 break;
+            case ANYCOMPATIBLEOID:
+            case ANYCOMPATIBLENONARRAYOID:
+                TupleDescInitEntry(tupdesc, i + 1,
+                                   NameStr(att->attname),
+                                   anyc_actuals.anyelement_type,
+                                   -1,
+                                   0);
+                TupleDescInitEntryCollation(tupdesc, i + 1, anycompatcollation);
+                break;
+            case ANYCOMPATIBLEARRAYOID:
+                TupleDescInitEntry(tupdesc, i + 1,
+                                   NameStr(att->attname),
+                                   anyc_actuals.anyarray_type,
+                                   -1,
+                                   0);
+                TupleDescInitEntryCollation(tupdesc, i + 1, anycompatcollation);
+                break;
+            case ANYCOMPATIBLERANGEOID:
+                TupleDescInitEntry(tupdesc, i + 1,
+                                   NameStr(att->attname),
+                                   anyc_actuals.anyrange_type,
+                                   -1,
+                                   0);
+                /* no collation should be attached to a range type */
+                break;
             default:
                 break;
         }
@@ -720,7 +817,9 @@ resolve_polymorphic_tupdesc(TupleDesc tupdesc, oidvector *declared_args,
  * Given the declared argument types and modes for a function, replace any
  * polymorphic types (ANYELEMENT etc) in argtypes[] with concrete data types
  * deduced from the input arguments found in call_expr.
- * Returns true if able to deduce all types, false if not.
+ *
+ * Returns true if able to deduce all types, false if necessary information
+ * is not provided (call_expr is NULL or arg types aren't identifiable).
  *
  * This is the same logic as resolve_polymorphic_tupdesc, but with a different
  * argument representation, and slightly different output responsibilities.
@@ -735,16 +834,21 @@ resolve_polymorphic_argtypes(int numargs, Oid *argtypes, char *argmodes,
     bool        have_anyelement_result = false;
     bool        have_anyarray_result = false;
     bool        have_anyrange_result = false;
+    bool        have_anycompatible_result = false;
+    bool        have_anycompatible_array_result = false;
+    bool        have_anycompatible_range_result = false;
     polymorphic_actuals poly_actuals;
+    polymorphic_actuals anyc_actuals;
     int            inargno;
     int            i;

     /*
      * First pass: resolve polymorphic inputs, check for outputs.  As in
      * resolve_polymorphic_tupdesc, we rely on the parser to have enforced
-     * type consistency.
+     * type consistency and coerced ANYCOMPATIBLE args to a common supertype.
      */
     memset(&poly_actuals, 0, sizeof(poly_actuals));
+    memset(&anyc_actuals, 0, sizeof(anyc_actuals));
     inargno = 0;
     for (i = 0; i < numargs; i++)
     {
@@ -808,6 +912,61 @@ resolve_polymorphic_argtypes(int numargs, Oid *argtypes, char *argmodes,
                     argtypes[i] = poly_actuals.anyrange_type;
                 }
                 break;
+            case ANYCOMPATIBLEOID:
+            case ANYCOMPATIBLENONARRAYOID:
+                if (argmode == PROARGMODE_OUT || argmode == PROARGMODE_TABLE)
+                {
+                    have_polymorphic_result = true;
+                    have_anycompatible_result = true;
+                }
+                else
+                {
+                    if (!OidIsValid(anyc_actuals.anyelement_type))
+                    {
+                        anyc_actuals.anyelement_type =
+                            get_call_expr_argtype(call_expr, inargno);
+                        if (!OidIsValid(anyc_actuals.anyelement_type))
+                            return false;
+                    }
+                    argtypes[i] = anyc_actuals.anyelement_type;
+                }
+                break;
+            case ANYCOMPATIBLEARRAYOID:
+                if (argmode == PROARGMODE_OUT || argmode == PROARGMODE_TABLE)
+                {
+                    have_polymorphic_result = true;
+                    have_anycompatible_array_result = true;
+                }
+                else
+                {
+                    if (!OidIsValid(anyc_actuals.anyarray_type))
+                    {
+                        anyc_actuals.anyarray_type =
+                            get_call_expr_argtype(call_expr, inargno);
+                        if (!OidIsValid(anyc_actuals.anyarray_type))
+                            return false;
+                    }
+                    argtypes[i] = anyc_actuals.anyarray_type;
+                }
+                break;
+            case ANYCOMPATIBLERANGEOID:
+                if (argmode == PROARGMODE_OUT || argmode == PROARGMODE_TABLE)
+                {
+                    have_polymorphic_result = true;
+                    have_anycompatible_range_result = true;
+                }
+                else
+                {
+                    if (!OidIsValid(anyc_actuals.anyrange_type))
+                    {
+                        anyc_actuals.anyrange_type =
+                            get_call_expr_argtype(call_expr, inargno);
+                        if (!OidIsValid(anyc_actuals.anyrange_type))
+                            return false;
+                    }
+                    argtypes[i] = anyc_actuals.anyrange_type;
+                }
+                break;
             default:
                 break;
         }
@@ -829,6 +988,15 @@ resolve_polymorphic_argtypes(int numargs, Oid *argtypes, char *argmodes,
     if (have_anyrange_result && !OidIsValid(poly_actuals.anyrange_type))
         resolve_anyrange_from_others(&poly_actuals);

+    if (have_anycompatible_result && !OidIsValid(anyc_actuals.anyelement_type))
+        resolve_anyelement_from_others(&anyc_actuals);
+
+    if (have_anycompatible_array_result && !OidIsValid(anyc_actuals.anyarray_type))
+        resolve_anyarray_from_others(&anyc_actuals);
+
+    if (have_anycompatible_range_result && !OidIsValid(anyc_actuals.anyrange_type))
+        resolve_anyrange_from_others(&anyc_actuals);
+
     /* And finally replace the output column types as needed */
     for (i = 0; i < numargs; i++)
     {
@@ -845,6 +1013,16 @@ resolve_polymorphic_argtypes(int numargs, Oid *argtypes, char *argmodes,
             case ANYRANGEOID:
                 argtypes[i] = poly_actuals.anyrange_type;
                 break;
+            case ANYCOMPATIBLEOID:
+            case ANYCOMPATIBLENONARRAYOID:
+                argtypes[i] = anyc_actuals.anyelement_type;
+                break;
+            case ANYCOMPATIBLEARRAYOID:
+                argtypes[i] = anyc_actuals.anyarray_type;
+                break;
+            case ANYCOMPATIBLERANGEOID:
+                argtypes[i] = anyc_actuals.anyrange_type;
+                break;
             default:
                 break;
         }
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 7fb574f..8387238 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -7106,6 +7106,42 @@
 { oid => '268', descr => 'I/O',
   proname => 'table_am_handler_out', prorettype => 'cstring',
   proargtypes => 'table_am_handler', prosrc => 'table_am_handler_out' },
+{ oid => '9559', descr => 'I/O',
+  proname => 'anycompatible_in', prorettype => 'anycompatible',
+  proargtypes => 'cstring', prosrc => 'anycompatible_in' },
+{ oid => '9560', descr => 'I/O',
+  proname => 'anycompatible_out', prorettype => 'cstring',
+  proargtypes => 'anycompatible', prosrc => 'anycompatible_out' },
+{ oid => '9561', descr => 'I/O',
+  proname => 'anycompatiblearray_in', prorettype => 'anycompatiblearray',
+  proargtypes => 'cstring', prosrc => 'anycompatiblearray_in' },
+{ oid => '9562', descr => 'I/O',
+  proname => 'anycompatiblearray_out', provolatile => 's',
+  prorettype => 'cstring', proargtypes => 'anycompatiblearray',
+  prosrc => 'anycompatiblearray_out' },
+{ oid => '9563', descr => 'I/O',
+  proname => 'anycompatiblearray_recv', provolatile => 's',
+  prorettype => 'anycompatiblearray', proargtypes => 'internal',
+  prosrc => 'anycompatiblearray_recv' },
+{ oid => '9564', descr => 'I/O',
+  proname => 'anycompatiblearray_send', provolatile => 's',
+  prorettype => 'bytea', proargtypes => 'anycompatiblearray',
+  prosrc => 'anycompatiblearray_send' },
+{ oid => '9565', descr => 'I/O',
+  proname => 'anycompatiblenonarray_in', prorettype => 'anycompatiblenonarray',
+  proargtypes => 'cstring', prosrc => 'anycompatiblenonarray_in' },
+{ oid => '9566', descr => 'I/O',
+  proname => 'anycompatiblenonarray_out', prorettype => 'cstring',
+  proargtypes => 'anycompatiblenonarray',
+  prosrc => 'anycompatiblenonarray_out' },
+{ oid => '9567', descr => 'I/O',
+  proname => 'anycompatiblerange_in', provolatile => 's',
+  prorettype => 'anycompatiblerange', proargtypes => 'cstring oid int4',
+  prosrc => 'anycompatiblerange_in' },
+{ oid => '9568', descr => 'I/O',
+  proname => 'anycompatiblerange_out', provolatile => 's',
+  prorettype => 'cstring', proargtypes => 'anycompatiblerange',
+  prosrc => 'anycompatiblerange_out' },

 # tablesample method handlers
 { oid => '3313', descr => 'BERNOULLI tablesample method handler',
diff --git a/src/include/catalog/pg_type.dat b/src/include/catalog/pg_type.dat
index b00597d..20d5167 100644
--- a/src/include/catalog/pg_type.dat
+++ b/src/include/catalog/pg_type.dat
@@ -590,5 +590,30 @@
   typname => 'anyrange', typlen => '-1', typbyval => 'f', typtype => 'p',
   typcategory => 'P', typinput => 'anyrange_in', typoutput => 'anyrange_out',
   typreceive => '-', typsend => '-', typalign => 'd', typstorage => 'x' },
+{ oid => '9550',
+  descr => 'pseudo-type representing a polymorphic common type',
+  typname => 'anycompatible', typlen => '4', typbyval => 't', typtype => 'p',
+  typcategory => 'P', typinput => 'anycompatible_in',
+  typoutput => 'anycompatible_out', typreceive => '-', typsend => '-',
+  typalign => 'i' },
+{ oid => '9551',
+  descr => 'pseudo-type representing an array of polymorphic common type elements',
+  typname => 'anycompatiblearray', typlen => '-1', typbyval => 'f',
+  typtype => 'p', typcategory => 'P', typinput => 'anycompatiblearray_in',
+  typoutput => 'anycompatiblearray_out',
+  typreceive => 'anycompatiblearray_recv', typsend => 'anycompatiblearray_send',
+  typalign => 'd', typstorage => 'x' },
+{ oid => '9552',
+  descr => 'pseudo-type representing a polymorphic common type that is not an array',
+  typname => 'anycompatiblenonarray', typlen => '4', typbyval => 't',
+  typtype => 'p', typcategory => 'P', typinput => 'anycompatiblenonarray_in',
+  typoutput => 'anycompatiblenonarray_out', typreceive => '-', typsend => '-',
+  typalign => 'i' },
+{ oid => '9553',
+  descr => 'pseudo-type representing a polymorphic common type that is a range',
+  typname => 'anycompatiblerange', typlen => '-1', typbyval => 'f',
+  typtype => 'p', typcategory => 'P', typinput => 'anycompatiblerange_in',
+  typoutput => 'anycompatiblerange_out', typreceive => '-', typsend => '-',
+  typalign => 'd', typstorage => 'x' },

 ]
diff --git a/src/include/catalog/pg_type.h b/src/include/catalog/pg_type.h
index 9789094..7b37562 100644
--- a/src/include/catalog/pg_type.h
+++ b/src/include/catalog/pg_type.h
@@ -295,12 +295,23 @@ typedef FormData_pg_type *Form_pg_type;

 /* Is a type OID a polymorphic pseudotype?    (Beware of multiple evaluation) */
 #define IsPolymorphicType(typid)  \
+    (IsPolymorphicTypeFamily1(typid) || \
+     IsPolymorphicTypeFamily2(typid))
+
+/* Code not part of polymorphic type resolution should not use these macros: */
+#define IsPolymorphicTypeFamily1(typid)  \
     ((typid) == ANYELEMENTOID || \
      (typid) == ANYARRAYOID || \
      (typid) == ANYNONARRAYOID || \
      (typid) == ANYENUMOID || \
      (typid) == ANYRANGEOID)

+#define IsPolymorphicTypeFamily2(typid)  \
+    ((typid) == ANYCOMPATIBLEOID || \
+     (typid) == ANYCOMPATIBLEARRAYOID || \
+     (typid) == ANYCOMPATIBLENONARRAYOID || \
+     (typid) == ANYCOMPATIBLERANGEOID)
+
 #endif                            /* EXPOSE_TO_CLIENT_CODE */


diff --git a/src/pl/plpgsql/src/pl_comp.c b/src/pl/plpgsql/src/pl_comp.c
index c8e43e6..828ff5a 100644
--- a/src/pl/plpgsql/src/pl_comp.c
+++ b/src/pl/plpgsql/src/pl_comp.c
@@ -507,11 +507,13 @@ do_compile(FunctionCallInfo fcinfo,
             {
                 if (forValidator)
                 {
-                    if (rettypeid == ANYARRAYOID)
+                    if (rettypeid == ANYARRAYOID ||
+                        rettypeid == ANYCOMPATIBLEARRAYOID)
                         rettypeid = INT4ARRAYOID;
-                    else if (rettypeid == ANYRANGEOID)
+                    else if (rettypeid == ANYRANGEOID ||
+                             rettypeid == ANYCOMPATIBLERANGEOID)
                         rettypeid = INT4RANGEOID;
-                    else        /* ANYELEMENT or ANYNONARRAY */
+                    else        /* ANYELEMENT or ANYNONARRAY or ANYCOMPATIBLE */
                         rettypeid = INT4OID;
                     /* XXX what could we use for ANYENUM? */
                 }
@@ -2493,12 +2495,16 @@ plpgsql_resolve_polymorphic_argtypes(int numargs,
                 case ANYELEMENTOID:
                 case ANYNONARRAYOID:
                 case ANYENUMOID:    /* XXX dubious */
+                case ANYCOMPATIBLEOID:
+                case ANYCOMPATIBLENONARRAYOID:
                     argtypes[i] = INT4OID;
                     break;
                 case ANYARRAYOID:
+                case ANYCOMPATIBLEARRAYOID:
                     argtypes[i] = INT4ARRAYOID;
                     break;
                 case ANYRANGEOID:
+                case ANYCOMPATIBLERANGEOID:
                     argtypes[i] = INT4RANGEOID;
                     break;
                 default:
diff --git a/src/test/regress/expected/aggregates.out b/src/test/regress/expected/aggregates.out
index f457b5b..47b5bf7 100644
--- a/src/test/regress/expected/aggregates.out
+++ b/src/test/regress/expected/aggregates.out
@@ -1950,6 +1950,30 @@ select least_agg(variadic array[q1,q2]) from int8_tbl;
  -4567890123456789
 (1 row)

+select cleast_agg(q1,q2) from int8_tbl;
+    cleast_agg
+-------------------
+ -4567890123456789
+(1 row)
+
+select cleast_agg(4.5,f1) from int4_tbl;
+ cleast_agg
+-------------
+ -2147483647
+(1 row)
+
+select cleast_agg(variadic array[4.5,f1]) from int4_tbl;
+ cleast_agg
+-------------
+ -2147483647
+(1 row)
+
+select pg_typeof(cleast_agg(variadic array[4.5,f1])) from int4_tbl;
+ pg_typeof
+-----------
+ numeric
+(1 row)
+
 -- test aggregates with common transition functions share the same states
 begin work;
 create type avg_state as (total bigint, count bigint);
diff --git a/src/test/regress/expected/create_aggregate.out b/src/test/regress/expected/create_aggregate.out
index a2eb999..dcf6909 100644
--- a/src/test/regress/expected/create_aggregate.out
+++ b/src/test/regress/expected/create_aggregate.out
@@ -59,13 +59,39 @@ create aggregate aggfns(integer,integer,text) (
    sfunc = aggfns_trans, stype = aggtype[], sspace = 10000,
    initcond = '{}'
 );
--- variadic aggregate
+-- check error cases that would require run-time type coercion
+create function least_accum(int8, int8) returns int8 language sql as
+  'select least($1, $2)';
+create aggregate least_agg(int4) (
+  stype = int8, sfunc = least_accum
+);  -- fails
+ERROR:  function least_accum(bigint, bigint) requires run-time type coercion
+drop function least_accum(int8, int8);
+create function least_accum(anycompatible, anycompatible)
+returns anycompatible language sql as
+  'select least($1, $2)';
+create aggregate least_agg(int4) (
+  stype = int8, sfunc = least_accum
+);  -- fails
+ERROR:  function least_accum(bigint, bigint) requires run-time type coercion
+create aggregate least_agg(int8) (
+  stype = int8, sfunc = least_accum
+);
+drop function least_accum(anycompatible, anycompatible) cascade;
+NOTICE:  drop cascades to function least_agg(bigint)
+-- variadic aggregates
 create function least_accum(anyelement, variadic anyarray)
 returns anyelement language sql as
   'select least($1, min($2[i])) from generate_subscripts($2,1) g(i)';
 create aggregate least_agg(variadic items anyarray) (
   stype = anyelement, sfunc = least_accum
 );
+create function cleast_accum(anycompatible, variadic anycompatiblearray)
+returns anycompatible language sql as
+  'select least($1, min($2[i])) from generate_subscripts($2,1) g(i)';
+create aggregate cleast_agg(variadic items anycompatiblearray) (
+  stype = anycompatible, sfunc = cleast_accum
+);
 -- test ordered-set aggs using built-in support functions
 create aggregate my_percentile_disc(float8 ORDER BY anyelement) (
   stype = internal,
diff --git a/src/test/regress/expected/opr_sanity.out b/src/test/regress/expected/opr_sanity.out
index 40468e8..3c0b21d 100644
--- a/src/test/regress/expected/opr_sanity.out
+++ b/src/test/regress/expected/opr_sanity.out
@@ -329,7 +329,7 @@ SELECT p1.oid, p1.proname
 FROM pg_proc as p1
 WHERE p1.prorettype IN
     ('anyelement'::regtype, 'anyarray'::regtype, 'anynonarray'::regtype,
-     'anyenum'::regtype, 'anyrange'::regtype)
+     'anyenum'::regtype)
   AND NOT
     ('anyelement'::regtype = ANY (p1.proargtypes) OR
      'anyarray'::regtype = ANY (p1.proargtypes) OR
@@ -337,22 +337,64 @@ WHERE p1.prorettype IN
      'anyenum'::regtype = ANY (p1.proargtypes) OR
      'anyrange'::regtype = ANY (p1.proargtypes))
 ORDER BY 2;
- oid  |     proname
-------+------------------
+ oid  |    proname
+------+----------------
  2296 | anyarray_in
  2502 | anyarray_recv
  2312 | anyelement_in
  3504 | anyenum_in
  2777 | anynonarray_in
- 3832 | anyrange_in
   750 | array_in
  2400 | array_recv
  3506 | enum_in
  3532 | enum_recv
+(9 rows)
+
+-- anyrange is tighter than the rest, can only resolve from anyrange input
+SELECT p1.oid, p1.proname
+FROM pg_proc as p1
+WHERE p1.prorettype = 'anyrange'::regtype
+  AND NOT
+     'anyrange'::regtype = ANY (p1.proargtypes)
+ORDER BY 2;
+ oid  |     proname
+------+------------------
+ 3832 | anyrange_in
  3876 | range_gist_union
  3834 | range_in
  3836 | range_recv
-(13 rows)
+(4 rows)
+
+-- similarly for the anycompatible family
+SELECT p1.oid, p1.proname
+FROM pg_proc as p1
+WHERE p1.prorettype IN
+    ('anycompatible'::regtype, 'anycompatiblearray'::regtype,
+     'anycompatiblenonarray'::regtype)
+  AND NOT
+    ('anycompatible'::regtype = ANY (p1.proargtypes) OR
+     'anycompatiblearray'::regtype = ANY (p1.proargtypes) OR
+     'anycompatiblenonarray'::regtype = ANY (p1.proargtypes) OR
+     'anycompatiblerange'::regtype = ANY (p1.proargtypes))
+ORDER BY 2;
+ oid  |         proname
+------+--------------------------
+ 9559 | anycompatible_in
+ 9561 | anycompatiblearray_in
+ 9563 | anycompatiblearray_recv
+ 9565 | anycompatiblenonarray_in
+(4 rows)
+
+SELECT p1.oid, p1.proname
+FROM pg_proc as p1
+WHERE p1.prorettype = 'anycompatiblerange'::regtype
+  AND NOT
+     'anycompatiblerange'::regtype = ANY (p1.proargtypes)
+ORDER BY 2;
+ oid  |        proname
+------+-----------------------
+ 9567 | anycompatiblerange_in
+(1 row)

 -- Look for functions that accept cstring and are neither datatype input
 -- functions nor encoding conversion functions.  It's almost never a good
diff --git a/src/test/regress/expected/plpgsql.out b/src/test/regress/expected/plpgsql.out
index dfc10e3..4599fc1 100644
--- a/src/test/regress/expected/plpgsql.out
+++ b/src/test/regress/expected/plpgsql.out
@@ -1823,6 +1823,51 @@ select f1(int4range(42, 49)) as int, f1(float8range(4.5, 7.8)) as num;
 (1 row)

 drop function f1(x anyrange);
+create function f1(x anycompatible, y anycompatible) returns anycompatiblearray as $$
+begin
+  return array[x, y];
+end$$ language plpgsql;
+select f1(2, 4) as int, f1(2, 4.5) as num;
+  int  |   num
+-------+---------
+ {2,4} | {2,4.5}
+(1 row)
+
+drop function f1(x anycompatible, y anycompatible);
+create function f1(x anycompatiblerange, y anycompatible, z anycompatible) returns anycompatiblearray as $$
+begin
+  return array[lower(x), upper(x), y, z];
+end$$ language plpgsql;
+select f1(int4range(42, 49), 11, 2::smallint) as int, f1(float8range(4.5, 7.8), 7.8, 11::real) as num;
+     int      |       num
+--------------+------------------
+ {42,49,11,2} | {4.5,7.8,7.8,11}
+(1 row)
+
+select f1(int4range(42, 49), 11, 4.5) as fail;  -- range type doesn't fit
+ERROR:  function f1(int4range, integer, numeric) does not exist
+LINE 1: select f1(int4range(42, 49), 11, 4.5) as fail;
+               ^
+HINT:  No function matches the given name and argument types. You might need to add explicit type casts.
+drop function f1(x anycompatiblerange, y anycompatible, z anycompatible);
+-- fail, can't infer type:
+create function f1(x anycompatible) returns anycompatiblerange as $$
+begin
+  return array[x + 1, x + 2];
+end$$ language plpgsql;
+ERROR:  cannot determine result data type
+DETAIL:  A result of type anycompatiblerange requires at least one input of type anycompatiblerange.
+create function f1(x anycompatiblerange, y anycompatiblearray) returns anycompatiblerange as $$
+begin
+  return x;
+end$$ language plpgsql;
+select f1(int4range(42, 49), array[11]) as int, f1(float8range(4.5, 7.8), array[7]) as num;
+   int   |    num
+---------+-----------
+ [42,49) | [4.5,7.8)
+(1 row)
+
+drop function f1(x anycompatiblerange, y anycompatiblearray);
 --
 -- Test handling of OUT parameters, including polymorphic cases.
 -- Note that RETURN is optional with OUT params; we try both ways.
@@ -1940,6 +1985,25 @@ select * from duplic('foo'::text);
 (1 row)

 drop function duplic(anyelement);
+create function duplic(in i anycompatiblerange, out j anycompatible, out k anycompatiblearray) as $$
+begin
+  j := lower(i);
+  k := array[lower(i),upper(i)];
+  return;
+end$$ language plpgsql;
+select * from duplic(int4range(42,49));
+ j  |    k
+----+---------
+ 42 | {42,49}
+(1 row)
+
+select * from duplic(textrange('aaa', 'bbb'));
+  j  |     k
+-----+-----------
+ aaa | {aaa,bbb}
+(1 row)
+
+drop function duplic(anycompatiblerange);
 --
 -- test PERFORM
 --
diff --git a/src/test/regress/expected/polymorphism.out b/src/test/regress/expected/polymorphism.out
index 331562d..bd854e3 100644
--- a/src/test/regress/expected/polymorphism.out
+++ b/src/test/regress/expected/polymorphism.out
@@ -72,6 +72,47 @@ select polyf(int4range(42, 49)) as int, polyf(float8range(4.5, 7.8)) as num;
 (1 row)

 drop function polyf(x anyrange);
+create function polyf(x anycompatible, y anycompatible) returns anycompatiblearray as $$
+  select array[x, y]
+$$ language sql;
+select polyf(2, 4) as int, polyf(2, 4.5) as num;
+  int  |   num
+-------+---------
+ {2,4} | {2,4.5}
+(1 row)
+
+drop function polyf(x anycompatible, y anycompatible);
+create function polyf(x anycompatiblerange, y anycompatible, z anycompatible) returns anycompatiblearray as $$
+  select array[lower(x), upper(x), y, z]
+$$ language sql;
+select polyf(int4range(42, 49), 11, 2::smallint) as int, polyf(float8range(4.5, 7.8), 7.8, 11::real) as num;
+     int      |       num
+--------------+------------------
+ {42,49,11,2} | {4.5,7.8,7.8,11}
+(1 row)
+
+select polyf(int4range(42, 49), 11, 4.5) as fail;  -- range type doesn't fit
+ERROR:  function polyf(int4range, integer, numeric) does not exist
+LINE 1: select polyf(int4range(42, 49), 11, 4.5) as fail;
+               ^
+HINT:  No function matches the given name and argument types. You might need to add explicit type casts.
+drop function polyf(x anycompatiblerange, y anycompatible, z anycompatible);
+-- fail, can't infer type:
+create function polyf(x anycompatible) returns anycompatiblerange as $$
+  select array[x + 1, x + 2]
+$$ language sql;
+ERROR:  cannot determine result data type
+DETAIL:  A result of type anycompatiblerange requires at least one input of type anycompatiblerange.
+create function polyf(x anycompatiblerange, y anycompatiblearray) returns anycompatiblerange as $$
+  select x
+$$ language sql;
+select polyf(int4range(42, 49), array[11]) as int, polyf(float8range(4.5, 7.8), array[7]) as num;
+   int   |    num
+---------+-----------
+ [42,49) | [4.5,7.8)
+(1 row)
+
+drop function polyf(x anycompatiblerange, y anycompatiblearray);
 --
 -- Polymorphic aggregate tests
 --
@@ -1621,3 +1662,212 @@ View definition:

 drop view dfview;
 drop function dfunc(anyelement, anyelement, bool);
+--
+-- Tests for ANYCOMPATIBLE polymorphism family
+--
+create function anyctest(anycompatible, anycompatible)
+returns anycompatible as $$
+  select greatest($1, $2)
+$$ language sql;
+select x, pg_typeof(x) from anyctest(11, 12) x;
+ x  | pg_typeof
+----+-----------
+ 12 | integer
+(1 row)
+
+select x, pg_typeof(x) from anyctest(11, 12.3) x;
+  x   | pg_typeof
+------+-----------
+ 12.3 | numeric
+(1 row)
+
+select x, pg_typeof(x) from anyctest(11, point(1,2)) x;  -- fail
+ERROR:  function anyctest(integer, point) does not exist
+LINE 1: select x, pg_typeof(x) from anyctest(11, point(1,2)) x;
+                                    ^
+HINT:  No function matches the given name and argument types. You might need to add explicit type casts.
+select x, pg_typeof(x) from anyctest('11', '12.3') x;  -- fail, should it work?
+ERROR:  could not determine polymorphic type because input has type unknown
+select x, pg_typeof(x) from anyctest('11', '12.3'::text) x;
+  x   | pg_typeof
+------+-----------
+ 12.3 | text
+(1 row)
+
+drop function anyctest(anycompatible, anycompatible);
+create function anyctest(anycompatible, anycompatible)
+returns anycompatiblearray as $$
+  select array[$1, $2]
+$$ language sql;
+select x, pg_typeof(x) from anyctest(11, 12) x;
+    x    | pg_typeof
+---------+-----------
+ {11,12} | integer[]
+(1 row)
+
+select x, pg_typeof(x) from anyctest(11, 12.3) x;
+     x     | pg_typeof
+-----------+-----------
+ {11,12.3} | numeric[]
+(1 row)
+
+select x, pg_typeof(x) from anyctest(11, array[1,2]) x;  -- fail
+ERROR:  function anyctest(integer, integer[]) does not exist
+LINE 1: select x, pg_typeof(x) from anyctest(11, array[1,2]) x;
+                                    ^
+HINT:  No function matches the given name and argument types. You might need to add explicit type casts.
+drop function anyctest(anycompatible, anycompatible);
+create function anyctest(anycompatible, anycompatiblearray)
+returns anycompatiblearray as $$
+  select array[$1] || $2
+$$ language sql;
+select x, pg_typeof(x) from anyctest(11, array[12]) x;
+    x    | pg_typeof
+---------+-----------
+ {11,12} | integer[]
+(1 row)
+
+select x, pg_typeof(x) from anyctest(11, array[12.3]) x;
+     x     | pg_typeof
+-----------+-----------
+ {11,12.3} | numeric[]
+(1 row)
+
+select x, pg_typeof(x) from anyctest(12.3, array[13]) x;
+     x     | pg_typeof
+-----------+-----------
+ {12.3,13} | numeric[]
+(1 row)
+
+select x, pg_typeof(x) from anyctest(12.3, '{13,14.4}') x;
+       x        | pg_typeof
+----------------+-----------
+ {12.3,13,14.4} | numeric[]
+(1 row)
+
+select x, pg_typeof(x) from anyctest(11, array[point(1,2)]) x;  -- fail
+ERROR:  function anyctest(integer, point[]) does not exist
+LINE 1: select x, pg_typeof(x) from anyctest(11, array[point(1,2)]) ...
+                                    ^
+HINT:  No function matches the given name and argument types. You might need to add explicit type casts.
+select x, pg_typeof(x) from anyctest(11, 12) x;  -- fail
+ERROR:  function anyctest(integer, integer) does not exist
+LINE 1: select x, pg_typeof(x) from anyctest(11, 12) x;
+                                    ^
+HINT:  No function matches the given name and argument types. You might need to add explicit type casts.
+drop function anyctest(anycompatible, anycompatiblearray);
+create function anyctest(anycompatible, anycompatiblerange)
+returns anycompatiblerange as $$
+  select $2
+$$ language sql;
+select x, pg_typeof(x) from anyctest(11, int4range(4,7)) x;
+   x   | pg_typeof
+-------+-----------
+ [4,7) | int4range
+(1 row)
+
+select x, pg_typeof(x) from anyctest(11, numrange(4,7)) x;
+   x   | pg_typeof
+-------+-----------
+ [4,7) | numrange
+(1 row)
+
+select x, pg_typeof(x) from anyctest(11, 12) x;  -- fail
+ERROR:  function anyctest(integer, integer) does not exist
+LINE 1: select x, pg_typeof(x) from anyctest(11, 12) x;
+                                    ^
+HINT:  No function matches the given name and argument types. You might need to add explicit type casts.
+select x, pg_typeof(x) from anyctest(11.2, int4range(4,7)) x;  -- fail
+ERROR:  function anyctest(numeric, int4range) does not exist
+LINE 1: select x, pg_typeof(x) from anyctest(11.2, int4range(4,7)) x...
+                                    ^
+HINT:  No function matches the given name and argument types. You might need to add explicit type casts.
+select x, pg_typeof(x) from anyctest(11.2, '[4,7)') x;  -- fail
+ERROR:  could not determine polymorphic type anycompatiblerange because input has type unknown
+drop function anyctest(anycompatible, anycompatiblerange);
+create function anyctest(anycompatiblerange, anycompatiblerange)
+returns anycompatible as $$
+  select lower($1) + upper($2)
+$$ language sql;
+select x, pg_typeof(x) from anyctest(int4range(11,12), int4range(4,7)) x;
+ x  | pg_typeof
+----+-----------
+ 18 | integer
+(1 row)
+
+select x, pg_typeof(x) from anyctest(int4range(11,12), numrange(4,7)) x; -- fail
+ERROR:  function anyctest(int4range, numrange) does not exist
+LINE 1: select x, pg_typeof(x) from anyctest(int4range(11,12), numra...
+                                    ^
+HINT:  No function matches the given name and argument types. You might need to add explicit type casts.
+drop function anyctest(anycompatiblerange, anycompatiblerange);
+-- fail, can't infer result type:
+create function anyctest(anycompatible)
+returns anycompatiblerange as $$
+  select $1
+$$ language sql;
+ERROR:  cannot determine result data type
+DETAIL:  A result of type anycompatiblerange requires at least one input of type anycompatiblerange.
+create function anyctest(anycompatiblenonarray, anycompatiblenonarray)
+returns anycompatiblearray as $$
+  select array[$1, $2]
+$$ language sql;
+select x, pg_typeof(x) from anyctest(11, 12) x;
+    x    | pg_typeof
+---------+-----------
+ {11,12} | integer[]
+(1 row)
+
+select x, pg_typeof(x) from anyctest(11, 12.3) x;
+     x     | pg_typeof
+-----------+-----------
+ {11,12.3} | numeric[]
+(1 row)
+
+select x, pg_typeof(x) from anyctest(array[11], array[1,2]) x;  -- fail
+ERROR:  function anyctest(integer[], integer[]) does not exist
+LINE 1: select x, pg_typeof(x) from anyctest(array[11], array[1,2]) ...
+                                    ^
+HINT:  No function matches the given name and argument types. You might need to add explicit type casts.
+drop function anyctest(anycompatiblenonarray, anycompatiblenonarray);
+create function anyctest(variadic anycompatiblearray)
+returns anycompatiblearray as $$
+begin
+  return $1;
+end;
+$$ language plpgsql;
+select x, pg_typeof(x) from anyctest(11, 12) x;
+    x    | pg_typeof
+---------+-----------
+ {11,12} | integer[]
+(1 row)
+
+select x, pg_typeof(x) from anyctest(11, 12.2) x;
+     x     | pg_typeof
+-----------+-----------
+ {11,12.2} | numeric[]
+(1 row)
+
+select x, pg_typeof(x) from anyctest(11, '12') x;
+    x    | pg_typeof
+---------+-----------
+ {11,12} | integer[]
+(1 row)
+
+select x, pg_typeof(x) from anyctest(11, '12.2') x;  -- fail
+ERROR:  invalid input syntax for type integer: "12.2"
+LINE 1: select x, pg_typeof(x) from anyctest(11, '12.2') x;
+                                                 ^
+select x, pg_typeof(x) from anyctest(variadic array[11, 12]) x;
+    x    | pg_typeof
+---------+-----------
+ {11,12} | integer[]
+(1 row)
+
+select x, pg_typeof(x) from anyctest(variadic array[11, 12.2]) x;
+     x     | pg_typeof
+-----------+-----------
+ {11,12.2} | numeric[]
+(1 row)
+
+drop function anyctest(variadic anycompatiblearray);
diff --git a/src/test/regress/expected/rangefuncs.out b/src/test/regress/expected/rangefuncs.out
index cdfc43e..7eced28 100644
--- a/src/test/regress/expected/rangefuncs.out
+++ b/src/test/regress/expected/rangefuncs.out
@@ -1557,6 +1557,59 @@ CREATE FUNCTION bad (f1 int, out f2 anyelement, out f3 anyarray)
 AS 'select $1, array[$1,$1]' LANGUAGE sql;
 ERROR:  cannot determine result data type
 DETAIL:  A result of type anyelement requires at least one input of type anyelement, anyarray, anynonarray, anyenum,
oranyrange. 
+CREATE FUNCTION dup (f1 anycompatible, f2 anycompatiblearray, f3 out anycompatible, f4 out anycompatiblearray)
+AS 'select $1, $2' LANGUAGE sql;
+SELECT dup(22, array[44]);
+    dup
+-----------
+ (22,{44})
+(1 row)
+
+SELECT dup(4.5, array[44]);
+    dup
+------------
+ (4.5,{44})
+(1 row)
+
+SELECT dup(22, array[44::bigint]);
+    dup
+-----------
+ (22,{44})
+(1 row)
+
+SELECT *, pg_typeof(f3), pg_typeof(f4) FROM dup(22, array[44::bigint]);
+ f3 |  f4  | pg_typeof | pg_typeof
+----+------+-----------+-----------
+ 22 | {44} | bigint    | bigint[]
+(1 row)
+
+DROP FUNCTION dup(f1 anycompatible, f2 anycompatiblearray);
+CREATE FUNCTION dup (f1 anycompatiblerange, f2 out anycompatible, f3 out anycompatiblearray, f4 out
anycompatiblerange)
+AS 'select lower($1), array[lower($1), upper($1)], $1' LANGUAGE sql;
+SELECT dup(int4range(4,7));
+         dup
+---------------------
+ (4,"{4,7}","[4,7)")
+(1 row)
+
+SELECT dup(numrange(4,7));
+         dup
+---------------------
+ (4,"{4,7}","[4,7)")
+(1 row)
+
+SELECT dup(textrange('aaa', 'bbb'));
+              dup
+-------------------------------
+ (aaa,"{aaa,bbb}","[aaa,bbb)")
+(1 row)
+
+DROP FUNCTION dup(f1 anycompatiblerange);
+-- fails, no way to deduce outputs
+CREATE FUNCTION bad (f1 anyarray, out f2 anycompatible, out f3 anycompatiblearray)
+AS 'select $1, array[$1,$1]' LANGUAGE sql;
+ERROR:  cannot determine result data type
+DETAIL:  A result of type anycompatible requires at least one input of type anycompatible, anycompatiblearray,
anycompatiblenonarray,or anycompatiblerange. 
 --
 -- table functions
 --
diff --git a/src/test/regress/expected/rangetypes.out b/src/test/regress/expected/rangetypes.out
index a28741a..c421f53 100644
--- a/src/test/regress/expected/rangetypes.out
+++ b/src/test/regress/expected/rangetypes.out
@@ -1405,6 +1405,32 @@ ERROR:  function rangetypes_sql(numrange, integer[]) does not exist
 LINE 1: select rangetypes_sql(numrange(1,10), ARRAY[2,20]);
                ^
 HINT:  No function matches the given name and argument types. You might need to add explicit type casts.
+create function anycompatiblearray_anycompatiblerange_func(a anycompatiblearray, r anycompatiblerange)
+  returns anycompatible as 'select $1[1] + lower($2);' language sql;
+select anycompatiblearray_anycompatiblerange_func(ARRAY[1,2], int4range(10,20));
+ anycompatiblearray_anycompatiblerange_func
+--------------------------------------------
+                                         11
+(1 row)
+
+select anycompatiblearray_anycompatiblerange_func(ARRAY[1,2], numrange(10,20));
+ anycompatiblearray_anycompatiblerange_func
+--------------------------------------------
+                                         11
+(1 row)
+
+-- should fail
+select anycompatiblearray_anycompatiblerange_func(ARRAY[1.1,2], int4range(10,20));
+ERROR:  function anycompatiblearray_anycompatiblerange_func(numeric[], int4range) does not exist
+LINE 1: select anycompatiblearray_anycompatiblerange_func(ARRAY[1.1,...
+               ^
+HINT:  No function matches the given name and argument types. You might need to add explicit type casts.
+drop function anycompatiblearray_anycompatiblerange_func(anycompatiblearray, anycompatiblerange);
+-- should fail
+create function bogus_func(anycompatible)
+  returns anycompatiblerange as 'select int4range(1,10)' language sql;
+ERROR:  cannot determine result data type
+DETAIL:  A result of type anycompatiblerange requires at least one input of type anycompatiblerange.
 --
 -- Arrays of ranges
 --
diff --git a/src/test/regress/expected/type_sanity.out b/src/test/regress/expected/type_sanity.out
index cd7fc03..274130e 100644
--- a/src/test/regress/expected/type_sanity.out
+++ b/src/test/regress/expected/type_sanity.out
@@ -131,14 +131,16 @@ WHERE p1.typinput = p2.oid AND NOT

 -- Check for type of the variadic array parameter's elements.
 -- provariadic should be ANYOID if the type of the last element is ANYOID,
--- ANYELEMENTOID if the type of the last element is ANYARRAYOID, and otherwise
--- the element type corresponding to the array type.
+-- ANYELEMENTOID if the type of the last element is ANYARRAYOID,
+-- ANYCOMPATIBLEOID if the type of the last element is ANYCOMPATIBLEARRAYOID,
+-- and otherwise the element type corresponding to the array type.
 SELECT oid::regprocedure, provariadic::regtype, proargtypes::regtype[]
 FROM pg_proc
 WHERE provariadic != 0
 AND case proargtypes[array_length(proargtypes, 1)-1]
-    WHEN 2276 THEN 2276 -- any -> any
-    WHEN 2277 THEN 2283 -- anyarray -> anyelement
+    WHEN '"any"'::regtype THEN '"any"'::regtype
+    WHEN 'anyarray'::regtype THEN 'anyelement'::regtype
+    WHEN 'anycompatiblearray'::regtype THEN 'anycompatible'::regtype
     ELSE (SELECT t.oid
           FROM pg_type t
           WHERE t.typarray = proargtypes[array_length(proargtypes, 1)-1])
diff --git a/src/test/regress/sql/aggregates.sql b/src/test/regress/sql/aggregates.sql
index 3e593f2..f04ac29 100644
--- a/src/test/regress/sql/aggregates.sql
+++ b/src/test/regress/sql/aggregates.sql
@@ -740,6 +740,10 @@ drop view aggordview1;
 select least_agg(q1,q2) from int8_tbl;
 select least_agg(variadic array[q1,q2]) from int8_tbl;

+select cleast_agg(q1,q2) from int8_tbl;
+select cleast_agg(4.5,f1) from int4_tbl;
+select cleast_agg(variadic array[4.5,f1]) from int4_tbl;
+select pg_typeof(cleast_agg(variadic array[4.5,f1])) from int4_tbl;

 -- test aggregates with common transition functions share the same states
 begin work;
diff --git a/src/test/regress/sql/create_aggregate.sql b/src/test/regress/sql/create_aggregate.sql
index fd7cd40..d4b4036 100644
--- a/src/test/regress/sql/create_aggregate.sql
+++ b/src/test/regress/sql/create_aggregate.sql
@@ -72,7 +72,31 @@ create aggregate aggfns(integer,integer,text) (
    initcond = '{}'
 );

--- variadic aggregate
+-- check error cases that would require run-time type coercion
+create function least_accum(int8, int8) returns int8 language sql as
+  'select least($1, $2)';
+
+create aggregate least_agg(int4) (
+  stype = int8, sfunc = least_accum
+);  -- fails
+
+drop function least_accum(int8, int8);
+
+create function least_accum(anycompatible, anycompatible)
+returns anycompatible language sql as
+  'select least($1, $2)';
+
+create aggregate least_agg(int4) (
+  stype = int8, sfunc = least_accum
+);  -- fails
+
+create aggregate least_agg(int8) (
+  stype = int8, sfunc = least_accum
+);
+
+drop function least_accum(anycompatible, anycompatible) cascade;
+
+-- variadic aggregates
 create function least_accum(anyelement, variadic anyarray)
 returns anyelement language sql as
   'select least($1, min($2[i])) from generate_subscripts($2,1) g(i)';
@@ -81,6 +105,14 @@ create aggregate least_agg(variadic items anyarray) (
   stype = anyelement, sfunc = least_accum
 );

+create function cleast_accum(anycompatible, variadic anycompatiblearray)
+returns anycompatible language sql as
+  'select least($1, min($2[i])) from generate_subscripts($2,1) g(i)';
+
+create aggregate cleast_agg(variadic items anycompatiblearray) (
+  stype = anycompatible, sfunc = cleast_accum
+);
+
 -- test ordered-set aggs using built-in support functions
 create aggregate my_percentile_disc(float8 ORDER BY anyelement) (
   stype = internal,
diff --git a/src/test/regress/sql/opr_sanity.sql b/src/test/regress/sql/opr_sanity.sql
index f06f245..389d5b2 100644
--- a/src/test/regress/sql/opr_sanity.sql
+++ b/src/test/regress/sql/opr_sanity.sql
@@ -273,7 +273,7 @@ SELECT p1.oid, p1.proname
 FROM pg_proc as p1
 WHERE p1.prorettype IN
     ('anyelement'::regtype, 'anyarray'::regtype, 'anynonarray'::regtype,
-     'anyenum'::regtype, 'anyrange'::regtype)
+     'anyenum'::regtype)
   AND NOT
     ('anyelement'::regtype = ANY (p1.proargtypes) OR
      'anyarray'::regtype = ANY (p1.proargtypes) OR
@@ -282,6 +282,37 @@ WHERE p1.prorettype IN
      'anyrange'::regtype = ANY (p1.proargtypes))
 ORDER BY 2;

+-- anyrange is tighter than the rest, can only resolve from anyrange input
+
+SELECT p1.oid, p1.proname
+FROM pg_proc as p1
+WHERE p1.prorettype = 'anyrange'::regtype
+  AND NOT
+     'anyrange'::regtype = ANY (p1.proargtypes)
+ORDER BY 2;
+
+-- similarly for the anycompatible family
+
+SELECT p1.oid, p1.proname
+FROM pg_proc as p1
+WHERE p1.prorettype IN
+    ('anycompatible'::regtype, 'anycompatiblearray'::regtype,
+     'anycompatiblenonarray'::regtype)
+  AND NOT
+    ('anycompatible'::regtype = ANY (p1.proargtypes) OR
+     'anycompatiblearray'::regtype = ANY (p1.proargtypes) OR
+     'anycompatiblenonarray'::regtype = ANY (p1.proargtypes) OR
+     'anycompatiblerange'::regtype = ANY (p1.proargtypes))
+ORDER BY 2;
+
+SELECT p1.oid, p1.proname
+FROM pg_proc as p1
+WHERE p1.prorettype = 'anycompatiblerange'::regtype
+  AND NOT
+     'anycompatiblerange'::regtype = ANY (p1.proargtypes)
+ORDER BY 2;
+
+
 -- Look for functions that accept cstring and are neither datatype input
 -- functions nor encoding conversion functions.  It's almost never a good
 -- idea to use cstring input for a function meant to be called from SQL;
diff --git a/src/test/regress/sql/plpgsql.sql b/src/test/regress/sql/plpgsql.sql
index c5e6e6e..425ad8e 100644
--- a/src/test/regress/sql/plpgsql.sql
+++ b/src/test/regress/sql/plpgsql.sql
@@ -1618,6 +1618,41 @@ select f1(int4range(42, 49)) as int, f1(float8range(4.5, 7.8)) as num;

 drop function f1(x anyrange);

+create function f1(x anycompatible, y anycompatible) returns anycompatiblearray as $$
+begin
+  return array[x, y];
+end$$ language plpgsql;
+
+select f1(2, 4) as int, f1(2, 4.5) as num;
+
+drop function f1(x anycompatible, y anycompatible);
+
+create function f1(x anycompatiblerange, y anycompatible, z anycompatible) returns anycompatiblearray as $$
+begin
+  return array[lower(x), upper(x), y, z];
+end$$ language plpgsql;
+
+select f1(int4range(42, 49), 11, 2::smallint) as int, f1(float8range(4.5, 7.8), 7.8, 11::real) as num;
+
+select f1(int4range(42, 49), 11, 4.5) as fail;  -- range type doesn't fit
+
+drop function f1(x anycompatiblerange, y anycompatible, z anycompatible);
+
+-- fail, can't infer type:
+create function f1(x anycompatible) returns anycompatiblerange as $$
+begin
+  return array[x + 1, x + 2];
+end$$ language plpgsql;
+
+create function f1(x anycompatiblerange, y anycompatiblearray) returns anycompatiblerange as $$
+begin
+  return x;
+end$$ language plpgsql;
+
+select f1(int4range(42, 49), array[11]) as int, f1(float8range(4.5, 7.8), array[7]) as num;
+
+drop function f1(x anycompatiblerange, y anycompatiblearray);
+
 --
 -- Test handling of OUT parameters, including polymorphic cases.
 -- Note that RETURN is optional with OUT params; we try both ways.
@@ -1699,6 +1734,18 @@ select * from duplic('foo'::text);

 drop function duplic(anyelement);

+create function duplic(in i anycompatiblerange, out j anycompatible, out k anycompatiblearray) as $$
+begin
+  j := lower(i);
+  k := array[lower(i),upper(i)];
+  return;
+end$$ language plpgsql;
+
+select * from duplic(int4range(42,49));
+select * from duplic(textrange('aaa', 'bbb'));
+
+drop function duplic(anycompatiblerange);
+
 --
 -- test PERFORM
 --
diff --git a/src/test/regress/sql/polymorphism.sql b/src/test/regress/sql/polymorphism.sql
index 9c7b43e..ba698b8 100644
--- a/src/test/regress/sql/polymorphism.sql
+++ b/src/test/regress/sql/polymorphism.sql
@@ -53,6 +53,37 @@ select polyf(int4range(42, 49)) as int, polyf(float8range(4.5, 7.8)) as num;

 drop function polyf(x anyrange);

+create function polyf(x anycompatible, y anycompatible) returns anycompatiblearray as $$
+  select array[x, y]
+$$ language sql;
+
+select polyf(2, 4) as int, polyf(2, 4.5) as num;
+
+drop function polyf(x anycompatible, y anycompatible);
+
+create function polyf(x anycompatiblerange, y anycompatible, z anycompatible) returns anycompatiblearray as $$
+  select array[lower(x), upper(x), y, z]
+$$ language sql;
+
+select polyf(int4range(42, 49), 11, 2::smallint) as int, polyf(float8range(4.5, 7.8), 7.8, 11::real) as num;
+
+select polyf(int4range(42, 49), 11, 4.5) as fail;  -- range type doesn't fit
+
+drop function polyf(x anycompatiblerange, y anycompatible, z anycompatible);
+
+-- fail, can't infer type:
+create function polyf(x anycompatible) returns anycompatiblerange as $$
+  select array[x + 1, x + 2]
+$$ language sql;
+
+create function polyf(x anycompatiblerange, y anycompatiblearray) returns anycompatiblerange as $$
+  select x
+$$ language sql;
+
+select polyf(int4range(42, 49), array[11]) as int, polyf(float8range(4.5, 7.8), array[7]) as num;
+
+drop function polyf(x anycompatiblerange, y anycompatiblearray);
+

 --
 -- Polymorphic aggregate tests
@@ -868,3 +899,101 @@ select * from dfview;

 drop view dfview;
 drop function dfunc(anyelement, anyelement, bool);
+
+--
+-- Tests for ANYCOMPATIBLE polymorphism family
+--
+
+create function anyctest(anycompatible, anycompatible)
+returns anycompatible as $$
+  select greatest($1, $2)
+$$ language sql;
+
+select x, pg_typeof(x) from anyctest(11, 12) x;
+select x, pg_typeof(x) from anyctest(11, 12.3) x;
+select x, pg_typeof(x) from anyctest(11, point(1,2)) x;  -- fail
+select x, pg_typeof(x) from anyctest('11', '12.3') x;  -- fail, should it work?
+select x, pg_typeof(x) from anyctest('11', '12.3'::text) x;
+
+drop function anyctest(anycompatible, anycompatible);
+
+create function anyctest(anycompatible, anycompatible)
+returns anycompatiblearray as $$
+  select array[$1, $2]
+$$ language sql;
+
+select x, pg_typeof(x) from anyctest(11, 12) x;
+select x, pg_typeof(x) from anyctest(11, 12.3) x;
+select x, pg_typeof(x) from anyctest(11, array[1,2]) x;  -- fail
+
+drop function anyctest(anycompatible, anycompatible);
+
+create function anyctest(anycompatible, anycompatiblearray)
+returns anycompatiblearray as $$
+  select array[$1] || $2
+$$ language sql;
+
+select x, pg_typeof(x) from anyctest(11, array[12]) x;
+select x, pg_typeof(x) from anyctest(11, array[12.3]) x;
+select x, pg_typeof(x) from anyctest(12.3, array[13]) x;
+select x, pg_typeof(x) from anyctest(12.3, '{13,14.4}') x;
+select x, pg_typeof(x) from anyctest(11, array[point(1,2)]) x;  -- fail
+select x, pg_typeof(x) from anyctest(11, 12) x;  -- fail
+
+drop function anyctest(anycompatible, anycompatiblearray);
+
+create function anyctest(anycompatible, anycompatiblerange)
+returns anycompatiblerange as $$
+  select $2
+$$ language sql;
+
+select x, pg_typeof(x) from anyctest(11, int4range(4,7)) x;
+select x, pg_typeof(x) from anyctest(11, numrange(4,7)) x;
+select x, pg_typeof(x) from anyctest(11, 12) x;  -- fail
+select x, pg_typeof(x) from anyctest(11.2, int4range(4,7)) x;  -- fail
+select x, pg_typeof(x) from anyctest(11.2, '[4,7)') x;  -- fail
+
+drop function anyctest(anycompatible, anycompatiblerange);
+
+create function anyctest(anycompatiblerange, anycompatiblerange)
+returns anycompatible as $$
+  select lower($1) + upper($2)
+$$ language sql;
+
+select x, pg_typeof(x) from anyctest(int4range(11,12), int4range(4,7)) x;
+select x, pg_typeof(x) from anyctest(int4range(11,12), numrange(4,7)) x; -- fail
+
+drop function anyctest(anycompatiblerange, anycompatiblerange);
+
+-- fail, can't infer result type:
+create function anyctest(anycompatible)
+returns anycompatiblerange as $$
+  select $1
+$$ language sql;
+
+create function anyctest(anycompatiblenonarray, anycompatiblenonarray)
+returns anycompatiblearray as $$
+  select array[$1, $2]
+$$ language sql;
+
+select x, pg_typeof(x) from anyctest(11, 12) x;
+select x, pg_typeof(x) from anyctest(11, 12.3) x;
+select x, pg_typeof(x) from anyctest(array[11], array[1,2]) x;  -- fail
+
+drop function anyctest(anycompatiblenonarray, anycompatiblenonarray);
+
+create function anyctest(variadic anycompatiblearray)
+returns anycompatiblearray as $$
+begin
+  return $1;
+end;
+$$ language plpgsql;
+
+select x, pg_typeof(x) from anyctest(11, 12) x;
+select x, pg_typeof(x) from anyctest(11, 12.2) x;
+select x, pg_typeof(x) from anyctest(11, '12') x;
+select x, pg_typeof(x) from anyctest(11, '12.2') x;  -- fail
+select x, pg_typeof(x) from anyctest(variadic array[11, 12]) x;
+select x, pg_typeof(x) from anyctest(variadic array[11, 12.2]) x;
+
+drop function anyctest(variadic anycompatiblearray);
diff --git a/src/test/regress/sql/rangefuncs.sql b/src/test/regress/sql/rangefuncs.sql
index 476b4f2..ae3119a 100644
--- a/src/test/regress/sql/rangefuncs.sql
+++ b/src/test/regress/sql/rangefuncs.sql
@@ -407,6 +407,27 @@ DROP FUNCTION dup(anyelement);
 CREATE FUNCTION bad (f1 int, out f2 anyelement, out f3 anyarray)
 AS 'select $1, array[$1,$1]' LANGUAGE sql;

+CREATE FUNCTION dup (f1 anycompatible, f2 anycompatiblearray, f3 out anycompatible, f4 out anycompatiblearray)
+AS 'select $1, $2' LANGUAGE sql;
+SELECT dup(22, array[44]);
+SELECT dup(4.5, array[44]);
+SELECT dup(22, array[44::bigint]);
+SELECT *, pg_typeof(f3), pg_typeof(f4) FROM dup(22, array[44::bigint]);
+
+DROP FUNCTION dup(f1 anycompatible, f2 anycompatiblearray);
+
+CREATE FUNCTION dup (f1 anycompatiblerange, f2 out anycompatible, f3 out anycompatiblearray, f4 out
anycompatiblerange)
+AS 'select lower($1), array[lower($1), upper($1)], $1' LANGUAGE sql;
+SELECT dup(int4range(4,7));
+SELECT dup(numrange(4,7));
+SELECT dup(textrange('aaa', 'bbb'));
+
+DROP FUNCTION dup(f1 anycompatiblerange);
+
+-- fails, no way to deduce outputs
+CREATE FUNCTION bad (f1 anyarray, out f2 anycompatible, out f3 anycompatiblearray)
+AS 'select $1, array[$1,$1]' LANGUAGE sql;
+
 --
 -- table functions
 --
diff --git a/src/test/regress/sql/rangetypes.sql b/src/test/regress/sql/rangetypes.sql
index 85eaa9b..4048b1d 100644
--- a/src/test/regress/sql/rangetypes.sql
+++ b/src/test/regress/sql/rangetypes.sql
@@ -456,6 +456,22 @@ create function rangetypes_sql(q anyrange, b anyarray, out c anyelement)
 select rangetypes_sql(int4range(1,10), ARRAY[2,20]);
 select rangetypes_sql(numrange(1,10), ARRAY[2,20]);  -- match failure

+create function anycompatiblearray_anycompatiblerange_func(a anycompatiblearray, r anycompatiblerange)
+  returns anycompatible as 'select $1[1] + lower($2);' language sql;
+
+select anycompatiblearray_anycompatiblerange_func(ARRAY[1,2], int4range(10,20));
+
+select anycompatiblearray_anycompatiblerange_func(ARRAY[1,2], numrange(10,20));
+
+-- should fail
+select anycompatiblearray_anycompatiblerange_func(ARRAY[1.1,2], int4range(10,20));
+
+drop function anycompatiblearray_anycompatiblerange_func(anycompatiblearray, anycompatiblerange);
+
+-- should fail
+create function bogus_func(anycompatible)
+  returns anycompatiblerange as 'select int4range(1,10)' language sql;
+
 --
 -- Arrays of ranges
 --
diff --git a/src/test/regress/sql/type_sanity.sql b/src/test/regress/sql/type_sanity.sql
index fed413b..4b492ce 100644
--- a/src/test/regress/sql/type_sanity.sql
+++ b/src/test/regress/sql/type_sanity.sql
@@ -106,15 +106,17 @@ WHERE p1.typinput = p2.oid AND NOT

 -- Check for type of the variadic array parameter's elements.
 -- provariadic should be ANYOID if the type of the last element is ANYOID,
--- ANYELEMENTOID if the type of the last element is ANYARRAYOID, and otherwise
--- the element type corresponding to the array type.
+-- ANYELEMENTOID if the type of the last element is ANYARRAYOID,
+-- ANYCOMPATIBLEOID if the type of the last element is ANYCOMPATIBLEARRAYOID,
+-- and otherwise the element type corresponding to the array type.

 SELECT oid::regprocedure, provariadic::regtype, proargtypes::regtype[]
 FROM pg_proc
 WHERE provariadic != 0
 AND case proargtypes[array_length(proargtypes, 1)-1]
-    WHEN 2276 THEN 2276 -- any -> any
-    WHEN 2277 THEN 2283 -- anyarray -> anyelement
+    WHEN '"any"'::regtype THEN '"any"'::regtype
+    WHEN 'anyarray'::regtype THEN 'anyelement'::regtype
+    WHEN 'anycompatiblearray'::regtype THEN 'anycompatible'::regtype
     ELSE (SELECT t.oid
           FROM pg_type t
           WHERE t.typarray = proargtypes[array_length(proargtypes, 1)-1])
diff --git a/doc/src/sgml/xfunc.sgml b/doc/src/sgml/xfunc.sgml
index ff51660..0bec854 100644
--- a/doc/src/sgml/xfunc.sgml
+++ b/doc/src/sgml/xfunc.sgml
@@ -1285,6 +1285,16 @@ SELECT make_array2(1, 2.5) AS numericarray;
  {1,2.5}
 (1 row)
 </screen>
+     Because the rules for common type resolution default to choosing
+     type <type>text</type> when all inputs are of unknown types, this
+     also works:
+<screen>
+SELECT make_array2('a', 'b') AS textarray;
+ textarray
+-----------
+ {a,b}
+(1 row)
+</screen>
     </para>

     <para>
diff --git a/src/backend/parser/parse_coerce.c b/src/backend/parser/parse_coerce.c
index 1e53f7c..645e4aa 100644
--- a/src/backend/parser/parse_coerce.c
+++ b/src/backend/parser/parse_coerce.c
@@ -2251,14 +2251,17 @@ enforce_generic_type_consistency(const Oid *actual_arg_types,
             {
                 /*
                  * Only way to get here is if all the ANYCOMPATIBLE args have
-                 * UNKNOWN inputs
-                 *
-                 * XXX shouldn't we use TEXT?  But not TEXTRANGE.
+                 * UNKNOWN inputs.  Resolve to TEXT as select_common_type()
+                 * would do.  That doesn't license us to use TEXTRANGE,
+                 * though.
                  */
-                ereport(ERROR,
-                        (errcode(ERRCODE_DATATYPE_MISMATCH),
-                         errmsg("could not determine polymorphic type because input has type %s",
-                                "unknown")));
+                anycompatible_typeid = TEXTOID;
+                anycompatible_array_typeid = TEXTARRAYOID;
+                if (have_anycompatible_range)
+                    ereport(ERROR,
+                            (errcode(ERRCODE_DATATYPE_MISMATCH),
+                             errmsg("could not determine polymorphic type %s because input has type %s",
+                                    "anycompatiblerange", "unknown")));
             }
         }

diff --git a/src/test/regress/expected/polymorphism.out b/src/test/regress/expected/polymorphism.out
index bd854e3..fd4ff91 100644
--- a/src/test/regress/expected/polymorphism.out
+++ b/src/test/regress/expected/polymorphism.out
@@ -1686,9 +1686,7 @@ ERROR:  function anyctest(integer, point) does not exist
 LINE 1: select x, pg_typeof(x) from anyctest(11, point(1,2)) x;
                                     ^
 HINT:  No function matches the given name and argument types. You might need to add explicit type casts.
-select x, pg_typeof(x) from anyctest('11', '12.3') x;  -- fail, should it work?
-ERROR:  could not determine polymorphic type because input has type unknown
-select x, pg_typeof(x) from anyctest('11', '12.3'::text) x;
+select x, pg_typeof(x) from anyctest('11', '12.3') x;  -- defaults to text
   x   | pg_typeof
 ------+-----------
  12.3 | text
diff --git a/src/test/regress/sql/polymorphism.sql b/src/test/regress/sql/polymorphism.sql
index ba698b8..ec89f3c 100644
--- a/src/test/regress/sql/polymorphism.sql
+++ b/src/test/regress/sql/polymorphism.sql
@@ -912,8 +912,7 @@ $$ language sql;
 select x, pg_typeof(x) from anyctest(11, 12) x;
 select x, pg_typeof(x) from anyctest(11, 12.3) x;
 select x, pg_typeof(x) from anyctest(11, point(1,2)) x;  -- fail
-select x, pg_typeof(x) from anyctest('11', '12.3') x;  -- fail, should it work?
-select x, pg_typeof(x) from anyctest('11', '12.3'::text) x;
+select x, pg_typeof(x) from anyctest('11', '12.3') x;  -- defaults to text

 drop function anyctest(anycompatible, anycompatible);


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