Remove obsoleted code relating to targetlist SRF evaluation.

Since 69f4b9c plain expression evaluation (and thus normal projection)
can't return sets of tuples anymore. Thus remove code dealing with
that possibility.

This will require adjustments in external code using
ExecEvalExpr()/ExecProject() - that should neither be hard nor very
common.

Author: Andres Freund and Tom Lane
Discussion: https://postgr.es/m/20160822214023.aaxz5l4igypowyri@alap3.anarazel.de

Author: anarazel

contrib/postgres_fdw/postgres_fdw.c

@@ -3444,7 +3444,7 @@ process_query_params(ExprContext *econtext,
 		bool		isNull;
 
 		/* Evaluate the parameter expression */
-		expr_value = ExecEvalExpr(expr_state, econtext, &isNull, NULL);
+		expr_value = ExecEvalExpr(expr_state, econtext, &isNull);
 
 		/*
 		 * Get string representation of each parameter value by invoking

src/backend/catalog/index.c

@@ -1805,8 +1805,7 @@ FormIndexDatum(IndexInfo *indexInfo,
 				elog(ERROR, "wrong number of index expressions");
 			iDatum = ExecEvalExprSwitchContext((ExprState *) lfirst(indexpr_item),
 											   GetPerTupleExprContext(estate),
-											   &isNull,
-											   NULL);
+											   &isNull);
 			indexpr_item = lnext(indexpr_item);
 		}
 		values[i] = iDatum;

src/backend/catalog/partition.c

@@ -1358,7 +1358,7 @@ get_qual_for_range(PartitionKey key, PartitionBoundSpec *spec)
 			test_exprstate = ExecInitExpr(test_expr, NULL);
 			test_result = ExecEvalExprSwitchContext(test_exprstate,
 											  GetPerTupleExprContext(estate),
-													&isNull, NULL);
+													&isNull);
 			MemoryContextSwitchTo(oldcxt);
 			FreeExecutorState(estate);
 
@@ -1630,8 +1630,7 @@ FormPartitionKeyDatum(PartitionDispatch pd,
 				elog(ERROR, "wrong number of partition key expressions");
 			datum = ExecEvalExprSwitchContext((ExprState *) lfirst(partexpr_item),
 											  GetPerTupleExprContext(estate),
-											  &isNull,
-											  NULL);
+											  &isNull);
 			partexpr_item = lnext(partexpr_item);
 		}
 		values[i] = datum;

src/backend/commands/copy.c

@@ -3394,7 +3394,7 @@ NextCopyFrom(CopyState cstate, ExprContext *econtext,
 		Assert(CurrentMemoryContext == econtext->ecxt_per_tuple_memory);
 
 		values[defmap[i]] = ExecEvalExpr(defexprs[i], econtext,
-										 &nulls[defmap[i]], NULL);
+										 &nulls[defmap[i]]);
 	}
 
 	return true;

src/backend/commands/prepare.c

@@ -413,8 +413,7 @@ EvaluateParams(PreparedStatement *pstmt, List *params,
 		prm->pflags = PARAM_FLAG_CONST;
 		prm->value = ExecEvalExprSwitchContext(n,
 											   GetPerTupleExprContext(estate),
-											   &prm->isnull,
-											   NULL);
+											   &prm->isnull);
 
 		i++;
 	}

src/backend/commands/tablecmds.c

@@ -4460,8 +4460,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 					values[ex->attnum - 1] = ExecEvalExpr(ex->exprstate,
 														  econtext,
-													 &isnull[ex->attnum - 1],
-														  NULL);
+													 &isnull[ex->attnum - 1]);
 				}
 
 				/*

src/backend/commands/typecmds.c

@@ -2735,7 +2735,7 @@ validateDomainConstraint(Oid domainoid, char *ccbin)
 
 				conResult = ExecEvalExprSwitchContext(exprstate,
 													  econtext,
-													  &isNull, NULL);
+													  &isNull);
 
 				if (!isNull && !DatumGetBool(conResult))
 				{

src/backend/executor/execAmi.c

@@ -59,7 +59,6 @@
 #include "utils/syscache.h"
 
 
-static bool TargetListSupportsBackwardScan(List *targetlist);
 static bool IndexSupportsBackwardScan(Oid indexid);
 
 
@@ -120,7 +119,7 @@ ExecReScan(PlanState *node)
 			UpdateChangedParamSet(node->righttree, node->chgParam);
 	}
 
-	/* Shut down any SRFs in the plan node's targetlist */
+	/* Call expression callbacks */
 	if (node->ps_ExprContext)
 		ReScanExprContext(node->ps_ExprContext);
 
@@ -460,8 +459,7 @@ ExecSupportsBackwardScan(Plan *node)
 	{
 		case T_Result:
 			if (outerPlan(node) != NULL)
-				return ExecSupportsBackwardScan(outerPlan(node)) &&
-					TargetListSupportsBackwardScan(node->targetlist);
+				return ExecSupportsBackwardScan(outerPlan(node));
 			else
 				return false;
 
@@ -478,13 +476,6 @@ ExecSupportsBackwardScan(Plan *node)
 				return true;
 			}
 
-		case T_SeqScan:
-		case T_TidScan:
-		case T_FunctionScan:
-		case T_ValuesScan:
-		case T_CteScan:
-			return TargetListSupportsBackwardScan(node->targetlist);
-
 		case T_SampleScan:
 			/* Simplify life for tablesample methods by disallowing this */
 			return false;
@@ -493,54 +484,41 @@ ExecSupportsBackwardScan(Plan *node)
 			return false;
 
 		case T_IndexScan:
-			return IndexSupportsBackwardScan(((IndexScan *) node)->indexid) &&
-				TargetListSupportsBackwardScan(node->targetlist);
+			return IndexSupportsBackwardScan(((IndexScan *) node)->indexid);
 
 		case T_IndexOnlyScan:
-			return IndexSupportsBackwardScan(((IndexOnlyScan *) node)->indexid) &&
-				TargetListSupportsBackwardScan(node->targetlist);
+			return IndexSupportsBackwardScan(((IndexOnlyScan *) node)->indexid);
 
 		case T_SubqueryScan:
-			return ExecSupportsBackwardScan(((SubqueryScan *) node)->subplan) &&
-				TargetListSupportsBackwardScan(node->targetlist);
+			return ExecSupportsBackwardScan(((SubqueryScan *) node)->subplan);
 
 		case T_CustomScan:
 			{
 				uint32		flags = ((CustomScan *) node)->flags;
 
-				if ((flags & CUSTOMPATH_SUPPORT_BACKWARD_SCAN) &&
-					TargetListSupportsBackwardScan(node->targetlist))
+				if (flags & CUSTOMPATH_SUPPORT_BACKWARD_SCAN)
 					return true;
 			}
 			return false;
 
+		case T_SeqScan:
+		case T_TidScan:
+		case T_FunctionScan:
+		case T_ValuesScan:
+		case T_CteScan:
 		case T_Material:
 		case T_Sort:
-			/* these don't evaluate tlist */
 			return true;
 
 		case T_LockRows:
 		case T_Limit:
-			/* these don't evaluate tlist */
 			return ExecSupportsBackwardScan(outerPlan(node));
 
 		default:
 			return false;
 	}
 }
 
-/*
- * If the tlist contains set-returning functions, we can't support backward
- * scan, because the TupFromTlist code is direction-ignorant.
- */
-static bool
-TargetListSupportsBackwardScan(List *targetlist)
-{
-	if (expression_returns_set((Node *) targetlist))
-		return false;
-	return true;
-}
-
 /*
  * An IndexScan or IndexOnlyScan node supports backward scan only if the
  * index's AM does.