Re: pgsql: Add basic JSON_TABLE() functionality

I wrote:
> We need to either nuke that ecpg warning entirely, or find a more
> robust way of detecting whether the gram.y complaint is conditional.
> I'll put a brown paper bag on my head before suggesting that maybe
> we could pay attention to how far the errcode is indented.  Perhaps
> a slightly nicer way is to assume it's conditional if any earlier
> line in the rule starts with "if".

The latter seems considerably safer, so I modified parse.pl along
those lines.  Eyeball comparison of gram.y with preproc.y verifies
that now ecpg will emit the warning only in rules where the backend
unconditionally reports FEATURE_NOT_SUPPORTED.

I suppose this needs to be back-patched.

            regards, tom lane

diff --git a/src/interfaces/ecpg/preproc/parse.pl b/src/interfaces/ecpg/preproc/parse.pl
index 87b512b2a1..fe8d3e5178 100644
--- a/src/interfaces/ecpg/preproc/parse.pl
+++ b/src/interfaces/ecpg/preproc/parse.pl
@@ -34,7 +34,8 @@ my $brace_indent = 0;
 my $yaccmode = 0;
 my $in_rule = 0;
 my $header_included = 0;
-my $feature_not_supported = 0;
+my $has_feature_not_supported = 0;
+my $has_if_command = 0;
 my $tokenmode = 0;

 my (%buff, $infield, $comment, %tokens, %addons);
@@ -151,12 +152,6 @@ sub main
 {
   line: while (<$parserfh>)
     {
-        if (/ERRCODE_FEATURE_NOT_SUPPORTED/)
-        {
-            $feature_not_supported = 1;
-            next line;
-        }
-
         chomp;

         # comment out the line below to make the result file match (blank line wise)
@@ -182,6 +177,13 @@ sub main
             $infield = 0;
         }

+        if ($yaccmode == 1)
+        {
+            # Check for rules that throw FEATURE_NOT_SUPPORTED
+            $has_feature_not_supported = 1 if /ERRCODE_FEATURE_NOT_SUPPORTED/;
+            $has_if_command = 1 if /^\s*if/;
+        }
+
         my $prec = 0;

         # Make sure any braces are split
@@ -541,20 +543,17 @@ sub dump_fields

         #Normal
         add_to_buffer('rules', $ln);
-        if ($feature_not_supported == 1)
+        if ($has_feature_not_supported and not $has_if_command)
         {
-
-            # we found an unsupported feature, but we have to
-            # filter out ExecuteStmt: CREATE OptTemp TABLE ...
-            # because the warning there is only valid in some situations
-            if ($flds->[0] ne 'create' || $flds->[2] ne 'table')
-            {
-                add_to_buffer('rules',
-                    'mmerror(PARSE_ERROR, ET_WARNING, "unsupported feature will be passed to server");'
-                );
-            }
-            $feature_not_supported = 0;
+            # The backend unconditionally reports
+            # FEATURE_NOT_SUPPORTED in this rule, so let's emit
+            # a warning on the ecpg side.
+            add_to_buffer('rules',
+                'mmerror(PARSE_ERROR, ET_WARNING, "unsupported feature will be passed to server");'
+            );
         }
+        $has_feature_not_supported = 0;
+        $has_if_command = 0;

         if ($len == 0)
         {