Move checking an explicit VARIADIC "any" argument into the parser.

This is more efficient and simpler . It does mean that an untyped NULL
can no longer be used in such cases, which should be mentioned in
Release Notes, but doesn't seem a terrible loss. The workaround is to
cast the NULL to some array type.

Pavel Stehule, reviewed by Jeevan Chalke.

src/backend/catalog/pg_aggregate.c

@@ -332,6 +332,7 @@ lookup_agg_function(List *fnName,
 	Oid			fnOid;
 	bool		retset;
 	int			nvargs;
+	Oid			vatype;
 	Oid		   *true_oid_array;
 	FuncDetailCode fdresult;
 	AclResult	aclresult;
@@ -346,7 +347,8 @@ lookup_agg_function(List *fnName,
 	 */
 	fdresult = func_get_detail(fnName, NIL, NIL,
 							   nargs, input_types, false, false,
-							   &fnOid, rettype, &retset, &nvargs,
+							   &fnOid, rettype, &retset,
+							   &nvargs, &vatype,
 							   &true_oid_array, NULL);
 
 	/* only valid case is a normal function not returning a set */

src/backend/parser/parse_func.c

@@ -79,6 +79,7 @@ ParseFuncOrColumn(ParseState *pstate, List *funcname, List *fargs,
 	Node	   *retval;
 	bool		retset;
 	int			nvargs;
+	Oid			vatype;
 	FuncDetailCode fdresult;
 
 	/*
@@ -214,7 +215,8 @@ ParseFuncOrColumn(ParseState *pstate, List *funcname, List *fargs,
 	fdresult = func_get_detail(funcname, fargs, argnames, nargs,
 							   actual_arg_types,
 							   !func_variadic, true,
-							   &funcid, &rettype, &retset, &nvargs,
+							   &funcid, &rettype, &retset,
+							   &nvargs, &vatype,
 							   &declared_arg_types, &argdefaults);
 	if (fdresult == FUNCDETAIL_COERCION)
 	{
@@ -382,6 +384,22 @@ ParseFuncOrColumn(ParseState *pstate, List *funcname, List *fargs,
 		fargs = lappend(fargs, newa);
 	}
 
+	/*
+	 * When function is called an explicit VARIADIC labeled parameter,
+	 * and the declared_arg_type is "any", then sanity check the actual
+	 * parameter type now - it must be an array.
+	 */
+	if (nargs > 0 && vatype == ANYOID && func_variadic)
+	{
+		Oid		va_arr_typid = actual_arg_types[nargs - 1];
+
+		if (!OidIsValid(get_element_type(va_arr_typid)))
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+					 errmsg("VARIADIC argument must be an array"),
+			  parser_errposition(pstate, exprLocation((Node *) llast(fargs)))));
+	}
+
 	/* build the appropriate output structure */
 	if (fdresult == FUNCDETAIL_NORMAL)
 	{
@@ -1033,6 +1051,7 @@ func_get_detail(List *funcname,
 				Oid *rettype,	/* return value */
 				bool *retset,	/* return value */
 				int *nvargs,	/* return value */
+				Oid *vatype,	/* return value */
 				Oid **true_typeids,		/* return value */
 				List **argdefaults)		/* optional return value */
 {
@@ -1251,6 +1270,7 @@ func_get_detail(List *funcname,
 		pform = (Form_pg_proc) GETSTRUCT(ftup);
 		*rettype = pform->prorettype;
 		*retset = pform->proretset;
+		*vatype = pform->provariadic;
 		/* fetch default args if caller wants 'em */
 		if (argdefaults && best_candidate->ndargs > 0)
 		{

src/backend/utils/adt/ruleutils.c

@@ -8584,6 +8584,7 @@ generate_function_name(Oid funcid, int nargs, List *argnames, Oid *argtypes,
 	Oid			p_rettype;
 	bool		p_retset;
 	int			p_nvargs;
+	Oid			p_vatype;
 	Oid		   *p_true_typeids;
 
 	proctup = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
@@ -8634,7 +8635,8 @@ generate_function_name(Oid funcid, int nargs, List *argnames, Oid *argtypes,
 							   NIL, argnames, nargs, argtypes,
 							   !use_variadic, true,
 							   &p_funcid, &p_rettype,
-							   &p_retset, &p_nvargs, &p_true_typeids, NULL);
+							   &p_retset, &p_nvargs, &p_vatype,
+							   &p_true_typeids, NULL);
 	if ((p_result == FUNCDETAIL_NORMAL ||
 		 p_result == FUNCDETAIL_AGGREGATE ||
 		 p_result == FUNCDETAIL_WINDOWFUNC) &&

src/backend/utils/adt/varlena.c

@@ -3820,7 +3820,6 @@ concat_internal(const char *sepstr, int argidx,
 	 */
 	if (get_fn_expr_variadic(fcinfo->flinfo))
 	{
-		Oid			arr_typid;
 		ArrayType  *arr;
 
 		/* Should have just the one argument */
@@ -3831,20 +3830,16 @@ concat_internal(const char *sepstr, int argidx,
 			return NULL;
 
 		/*
-		 * Non-null argument had better be an array.  The parser doesn't
-		 * enforce this for VARIADIC ANY functions (maybe it should?), so that
-		 * check uses ereport not just elog.
+		 * Non-null argument had better be an array
+		 *
+		 * Correct values are ensured by parser check, but this function
+		 * can be called directly, bypassing the parser, so we should do
+		 * some minimal check too - this form of call requires correctly set
+		 * expr argtype in flinfo.
 		 */
-		arr_typid = get_fn_expr_argtype(fcinfo->flinfo, argidx);
-		if (!OidIsValid(arr_typid))
-			elog(ERROR, "could not determine data type of concat() input");
-
-		if (!OidIsValid(get_element_type(arr_typid)))
-			ereport(ERROR,
-					(errcode(ERRCODE_DATATYPE_MISMATCH),
-					 errmsg("VARIADIC argument must be an array")));
+		Assert(OidIsValid(get_fn_expr_argtype(fcinfo->flinfo, argidx)));
+		Assert(OidIsValid(get_element_type(get_fn_expr_argtype(fcinfo->flinfo, argidx))));
 
-		/* OK, safe to fetch the array value */
 		arr = PG_GETARG_ARRAYTYPE_P(argidx);
 
 		/*
@@ -4049,7 +4044,6 @@ text_format(PG_FUNCTION_ARGS)
 	/* If argument is marked VARIADIC, expand array into elements */
 	if (get_fn_expr_variadic(fcinfo->flinfo))
 	{
-		Oid			arr_typid;
 		ArrayType  *arr;
 		int16		elmlen;
 		bool		elmbyval;
@@ -4065,20 +4059,16 @@ text_format(PG_FUNCTION_ARGS)
 		else
 		{
 			/*
-			 * Non-null argument had better be an array.  The parser doesn't
-			 * enforce this for VARIADIC ANY functions (maybe it should?), so
-			 * that check uses ereport not just elog.
+			 * Non-null argument had better be an array
+			 *
+			 * Correct values are ensured by parser check, but this function
+			 * can be called directly, bypassing the parser, so we should do
+			 * some minimal check too - this form of call requires correctly set
+			 * expr argtype in flinfo.
 			 */
-			arr_typid = get_fn_expr_argtype(fcinfo->flinfo, 1);
-			if (!OidIsValid(arr_typid))
-				elog(ERROR, "could not determine data type of format() input");
-
-			if (!OidIsValid(get_element_type(arr_typid)))
-				ereport(ERROR,
-						(errcode(ERRCODE_DATATYPE_MISMATCH),
-						 errmsg("VARIADIC argument must be an array")));
+			Assert(OidIsValid(get_fn_expr_argtype(fcinfo->flinfo, 1)));
+			Assert(OidIsValid(get_element_type(get_fn_expr_argtype(fcinfo->flinfo, 1))));
 
-			/* OK, safe to fetch the array value */
 			arr = PG_GETARG_ARRAYTYPE_P(1);
 
 			/* Get info about array element type */

src/include/parser/parse_func.h

@@ -52,8 +52,8 @@ extern FuncDetailCode func_get_detail(List *funcname,
 				int nargs, Oid *argtypes,
 				bool expand_variadic, bool expand_defaults,
 				Oid *funcid, Oid *rettype,
-				bool *retset, int *nvargs, Oid **true_typeids,
-				List **argdefaults);
+				bool *retset, int *nvargs, Oid *vatype,
+				Oid **true_typeids, List **argdefaults);
 
 extern int func_match_argtypes(int nargs,
 					Oid *input_typeids,

src/test/regress/expected/text.out

@@ -149,13 +149,13 @@ select concat_ws(',', variadic array[1,2,3]);
  1,2,3
 (1 row)
 
-select concat_ws(',', variadic NULL);
+select concat_ws(',', variadic NULL::int[]);
  concat_ws 
 -----------
  
 (1 row)
 
-select concat(variadic NULL) is NULL;
+select concat(variadic NULL::int[]) is NULL;
  ?column? 
 ----------
  t
@@ -170,6 +170,8 @@ select concat(variadic '{}'::int[]) = '';
 --should fail
 select concat_ws(',', variadic 10);
 ERROR:  VARIADIC argument must be an array
+LINE 1: select concat_ws(',', variadic 10);
+                                       ^
 /*
  * format
  */
@@ -315,8 +317,8 @@ select format('%2$s, %1$s', variadic array[1, 2]);
  2, 1
 (1 row)
 
--- variadic argument can be NULL, but should not be referenced
-select format('Hello', variadic NULL);
+-- variadic argument can be array type NULL, but should not be referenced
+select format('Hello', variadic NULL::int[]);
  format 
 --------
  Hello

src/test/regress/sql/text.sql

@@ -47,8 +47,8 @@ select quote_literal(e'\\');
 -- check variadic labeled argument
 select concat(variadic array[1,2,3]);
 select concat_ws(',', variadic array[1,2,3]);
-select concat_ws(',', variadic NULL);
-select concat(variadic NULL) is NULL;
+select concat_ws(',', variadic NULL::int[]);
+select concat(variadic NULL::int[]) is NULL;
 select concat(variadic '{}'::int[]) = '';
 --should fail
 select concat_ws(',', variadic 10);
@@ -93,8 +93,8 @@ select format('%s, %s', variadic array[true, false]::text[]);
 -- check variadic with positional placeholders
 select format('%2$s, %1$s', variadic array['first', 'second']);
 select format('%2$s, %1$s', variadic array[1, 2]);
--- variadic argument can be NULL, but should not be referenced
-select format('Hello', variadic NULL);
+-- variadic argument can be array type NULL, but should not be referenced
+select format('Hello', variadic NULL::int[]);
 -- variadic argument allows simulating more than FUNC_MAX_ARGS parameters
 select format(string_agg('%s',','), variadic array_agg(i))
 from generate_series(1,200) g(i);