fix CustomEvalParamExternCompat(), many thanks to Alexander Kuzmenkov

Author: funbringer

src/include/compat/pg_compat.h

@@ -864,15 +864,15 @@ extern AttrNumber *convert_tuples_by_name_map(TupleDesc indesc,
 
 /* See ExecEvalParamExtern() */
 static inline ParamExternData *
-CustomEvalParamExternCompat(Param *param, ParamListInfo params)
+CustomEvalParamExternCompat(Param *param,
+							ParamListInfo params,
+							ParamExternData *prmdata)
 {
 	ParamExternData *prm;
 
 #if PG_VERSION_NUM >= 110000
-	ParamExternData prmdata;
-
 	if (params->paramFetch != NULL)
-		prm = params->paramFetch(params, param->paramid, false, &prmdata);
+		prm = params->paramFetch(params, param->paramid, false, prmdata);
 	else
 		prm = &params->params[param->paramid - 1];
 #else

src/planner_tree_modification.c

@@ -971,7 +971,10 @@ eval_extern_params_mutator(Node *node, ParamListInfo params)
 			param->paramid > 0 &&
 			param->paramid <= params->numParams)
 		{
-			ParamExternData *prm = CustomEvalParamExternCompat(param, params);
+			ParamExternData		prmdata; /* storage for 'prm' (PG 11) */
+			ParamExternData	   *prm = CustomEvalParamExternCompat(param,
+																  params,
+																  &prmdata);
 
 			if (OidIsValid(prm->ptype))
 			{