Run input function allowing soft errors only

When parsing WITH clause arguments for ALTER TABLE to extract
compression parameters, syntax errors in the text format are caught
using PG_TRY and PG_CATCH and then returning an indication if the parse
succeeded or not.

If an out of memory error occurs inside execution of the input function
and this error is caught, it can continue executing and potentially
cause cascading out of memory errors and in the end exhausing the error
stack.

This commit solves this by using `InputFunctionCallSafe` rather than
catching the error, allowing soft errors like a syntax error to return
with a failure but propagating hard errors like out-of-memory errors,
allowing the backend to deal with it properly.

Author: mkindahl

src/with_clause_parser.c

@@ -9,6 +9,7 @@
 #include <access/htup_details.h>
 #include <catalog/pg_type.h>
 #include <commands/defrem.h>
+#include <nodes/miscnodes.h>
 #include <nodes/parsenodes.h>
 #include <utils/builtins.h>
 #include <utils/lsyscache.h>
@@ -140,6 +141,8 @@ parse_arg(WithClauseDefinition arg, DefElem *def)
 	Datum val;
 	Oid in_fn;
 	Oid typIOParam;
+	ErrorSaveContext escontext = { T_ErrorSaveContext };
+	FmgrInfo flinfo;
 
 	if (!OidIsValid(arg.type_id))
 		ereport(ERROR,
@@ -161,11 +164,9 @@ parse_arg(WithClauseDefinition arg, DefElem *def)
 
 	Assert(OidIsValid(in_fn));
 
-	PG_TRY();
-	{
-		val = OidInputFunctionCall(in_fn, value, typIOParam, -1);
-	}
-	PG_CATCH();
+	fmgr_info(in_fn, &flinfo);
+
+	if (!InputFunctionCallSafe(&flinfo, value, typIOParam, -1, (Node *) &escontext, &val))
 	{
 		Form_pg_type typetup;
 		HeapTuple tup = SearchSysCache1(TYPEOID, ObjectIdGetDatum(arg.type_id));
@@ -186,6 +187,6 @@ parse_arg(WithClauseDefinition arg, DefElem *def)
 						 def->defname,
 						 NameStr(typetup->typname))));
 	}
-	PG_END_TRY();
+
 	return val;
 }