Re: remaining sql/json patches

+/*
+ * Evaluate or return the step address to evaluate a coercion of a JSON item
+ * to the target type.  The former if the coercion must be done right away by
+ * calling the target type's input function, and for some types, by calling
+ * json_populate_type().
+ *
+ * Returns the step address to be performed next.
+ */
+void
+ExecEvalJsonCoercionViaPopulateOrIO(ExprState *state, ExprEvalStep *op,
+ ExprContext *econtext)

the comment seems not right? it does return anything. it did the evaluation.

some logic in ExecEvalJsonCoercionViaPopulateOrIO, like if
(SOFT_ERROR_OCCURRED(escontext_p)) and if
(!InputFunctionCallSafe){...}, seems validated twice,
ExecEvalJsonCoercionFinish also did it. I uncommented the following
part, and still passed the test.
/src/backend/executor/execExprInterp.c
4452: // if (SOFT_ERROR_OCCURRED(escontext_p))
4453: // {
4454: // post_eval->error.value = BoolGetDatum(true);
4455: // *op->resvalue = (Datum) 0;
4456: // *op->resnull = true;
4457: // }

4470: // post_eval->error.value = BoolGetDatum(true);
4471: // *op->resnull = true;
4472: // *op->resvalue = (Datum) 0;
4473: return;

Correct me if I'm wrong.
like in "empty array on empty empty object on error", the "empty
array" refers to constant literal '[]' the assumed data type is jsonb,
the "empty object" refers to const literal '{}', the assumed data type
is jsonb.

--these two queries will fail very early, before ExecEvalJsonExprPath.
SELECT JSON_QUERY(jsonb '{"a":[3,4]}', '$.a' RETURNING int4range
default '[1.1,2]' on error);
SELECT JSON_QUERY(jsonb '{"a":[3,4]}', '$.a' RETURNING int4range
default '[1.1,2]' on empty);

-----these four will fail later, and will call
ExecEvalJsonCoercionViaPopulateOrIO twice.
SELECT JSON_QUERY(jsonb '{"a":[3,4]}', '$.z' RETURNING int4range empty
object on empty empty object on error);
SELECT JSON_QUERY(jsonb '{"a":[3,4]}', '$.z' RETURNING int4range empty
array on empty empty array on error);
SELECT JSON_QUERY(jsonb '{"a":[3,4]}', '$.z' RETURNING int4range empty
array on empty empty object on error);
SELECT JSON_QUERY(jsonb '{"a":[3,4]}', '$.z' RETURNING int4range empty
object on empty empty array on error);

-----however these four will not fail.
SELECT JSON_QUERY(jsonb '{"a":[3,4]}', '$.z' RETURNING int4range empty
object on error);
SELECT JSON_QUERY(jsonb '{"a":[3,4]}', '$.z' RETURNING int4range empty
array on error);
SELECT JSON_QUERY(jsonb '{"a":[3,4]}', '$.z' RETURNING int4range empty
array on empty);
SELECT JSON_QUERY(jsonb '{"a":[3,4]}', '$.z' RETURNING int4range empty
object on empty);

should the last four query fail or just return null?