Support for OUT parameters in procedures

Unlike for functions, OUT parameters for procedures are part of the
signature.  Therefore, they have to be listed in pg_proc.proargtypes
as well as mentioned in ALTER PROCEDURE and DROP PROCEDURE.

Reviewed-by: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
Reviewed-by: Pavel Stehule <pavel.stehule@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/2b8490fe-51af-e671-c504-47359dc453c5@2ndquadrant.com

1 files changed, 33 insertions, 24 deletions

diff --git a/src/backend/commands/functioncmds.c b/src/backend/commands/functioncmds.c
index e236581a8e0..c3ce480c8f5 100644
--- a/src/backend/commands/functioncmds.c
+++ b/src/backend/commands/functioncmds.c
@@ -194,8 +194,8 @@ interpret_function_parameter_list(ParseState *pstate,
 								  Oid *requiredResultType)
 {
 	int			parameterCount = list_length(parameters);
-	Oid		   *inTypes;
-	int			inCount = 0;
+	Oid		   *sigArgTypes;
+	int			sigArgCount = 0;
 	Datum	   *allTypes;
 	Datum	   *paramModes;
 	Datum	   *paramNames;
@@ -209,7 +209,7 @@ interpret_function_parameter_list(ParseState *pstate,
 	*variadicArgType = InvalidOid;	/* default result */
 	*requiredResultType = InvalidOid;	/* default result */
 
-	inTypes = (Oid *) palloc(parameterCount * sizeof(Oid));
+	sigArgTypes = (Oid *) palloc(parameterCount * sizeof(Oid));
 	allTypes = (Datum *) palloc(parameterCount * sizeof(Datum));
 	paramModes = (Datum *) palloc(parameterCount * sizeof(Datum));
 	paramNames = (Datum *) palloc0(parameterCount * sizeof(Datum));
@@ -281,25 +281,21 @@ interpret_function_parameter_list(ParseState *pstate,
 						 errmsg("functions cannot accept set arguments")));
 		}
 
-		if (objtype == OBJECT_PROCEDURE)
-		{
-			if (fp->mode == FUNC_PARAM_OUT)
-				ereport(ERROR,
-						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-						 errmsg("procedures cannot have OUT arguments"),
-						 errhint("INOUT arguments are permitted.")));
-		}
-
 		/* handle input parameters */
 		if (fp->mode != FUNC_PARAM_OUT && fp->mode != FUNC_PARAM_TABLE)
+			isinput = true;
+
+		/* handle signature parameters */
+		if (fp->mode == FUNC_PARAM_IN || fp->mode == FUNC_PARAM_INOUT ||
+			(objtype == OBJECT_PROCEDURE && fp->mode == FUNC_PARAM_OUT) ||
+			fp->mode == FUNC_PARAM_VARIADIC)
 		{
-			/* other input parameters can't follow a VARIADIC parameter */
+			/* other signature parameters can't follow a VARIADIC parameter */
 			if (varCount > 0)
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
-						 errmsg("VARIADIC parameter must be the last input parameter")));
-			inTypes[inCount++] = toid;
-			isinput = true;
+						 errmsg("VARIADIC parameter must be the last signature parameter")));
+			sigArgTypes[sigArgCount++] = toid;
 		}
 
 		/* handle output parameters */
@@ -429,7 +425,7 @@ interpret_function_parameter_list(ParseState *pstate,
 	}
 
 	/* Now construct the proper outputs as needed */
-	*parameterTypes = buildoidvector(inTypes, inCount);
+	*parameterTypes = buildoidvector(sigArgTypes, sigArgCount);
 
 	if (outCount > 0 || varCount > 0)
 	{
@@ -2067,6 +2063,9 @@ ExecuteCallStmt(CallStmt *stmt, ParamListInfo params, bool atomic, DestReceiver
 	int			nargs;
 	int			i;
 	AclResult	aclresult;
+	Oid		   *argtypes;
+	char	  **argnames;
+	char	   *argmodes;
 	FmgrInfo	flinfo;
 	CallContext *callcontext;
 	EState	   *estate;
@@ -2127,6 +2126,8 @@ ExecuteCallStmt(CallStmt *stmt, ParamListInfo params, bool atomic, DestReceiver
 											tp);
 	nargs = list_length(fexpr->args);
 
+	get_func_arg_info(tp, &argtypes, &argnames, &argmodes);
+
 	ReleaseSysCache(tp);
 
 	/* safety check; see ExecInitFunc() */
@@ -2156,16 +2157,24 @@ ExecuteCallStmt(CallStmt *stmt, ParamListInfo params, bool atomic, DestReceiver
 	i = 0;
 	foreach(lc, fexpr->args)
 	{
-		ExprState  *exprstate;
-		Datum		val;
-		bool		isnull;
+		if (argmodes && argmodes[i] == PROARGMODE_OUT)
+		{
+			fcinfo->args[i].value = 0;
+			fcinfo->args[i].isnull = true;
+		}
+		else
+		{
+			ExprState  *exprstate;
+			Datum		val;
+			bool		isnull;
 
-		exprstate = ExecPrepareExpr(lfirst(lc), estate);
+			exprstate = ExecPrepareExpr(lfirst(lc), estate);
 
-		val = ExecEvalExprSwitchContext(exprstate, econtext, &isnull);
+			val = ExecEvalExprSwitchContext(exprstate, econtext, &isnull);
 
-		fcinfo->args[i].value = val;
-		fcinfo->args[i].isnull = isnull;
+			fcinfo->args[i].value = val;
+			fcinfo->args[i].isnull = isnull;
+		}
 
 		i++;
 	}