Remove bogus assertion in transformExpressionList().

tglsfdc · tglsfdc · commit cf33fb7f4a19 · 2021-10-19T11:35:15.000-04:00
I think when I added this assertion (in commit 8f889b1), I was only thinking of the use of transformExpressionList at top level of INSERT and VALUES. But it's also called by transformRowExpr(), which can certainly occur in an UPDATE targetlist, so it's inappropriate to suppose that p_multiassign_exprs must be empty. Besides, since the input is not expected to contain ResTargets, there's no reason it should contain MultiAssignRefs either. Hence this code need not be concerned about the state of p_multiassign_exprs, and we should just drop the assertion. Per bug #17236 from ocean_li_996. It's been wrong for years, so back-patch to all supported branches. Discussion: https://postgr.es/m/17236-3210de9bcba1d7ca@postgresql.org
diff --git a/src/backend/parser/parse_target.c b/src/backend/parser/parse_target.c
@@ -221,7 +221,9 @@ transformTargetList(ParseState *pstate, List *targetlist,
  * This is the identical transformation to transformTargetList, except that
  * the input list elements are bare expressions without ResTarget decoration,
  * and the output elements are likewise just expressions without TargetEntry
- * decoration.  We use this for ROW() and VALUES() constructs.
+ * decoration.  Also, we don't expect any multiassign constructs within the
+ * list, so there's nothing to do for that.  We use this for ROW() and
+ * VALUES() constructs.
  *
  * exprKind is not enough to tell us whether to allow SetToDefault, so
  * an additional flag is needed for that.
@@ -283,9 +285,6 @@ transformExpressionList(ParseState *pstate, List *exprlist,
 		result = lappend(result, e);
 	}
 
-	/* Shouldn't have any multiassign items here */
-	Assert(pstate->p_multiassign_exprs == NIL);
-
 	return result;
 }
 

Original file line number	Diff line number	Diff line change
`@@ -221,7 +221,9 @@ transformTargetList(ParseState pstate, List targetlist,`
`221`	`221`	`* This is the identical transformation to transformTargetList, except that`
`222`	`222`	`* the input list elements are bare expressions without ResTarget decoration,`
`223`	`223`	`* and the output elements are likewise just expressions without TargetEntry`
`224`		`- * decoration. We use this for ROW() and VALUES() constructs.`
	`224`	`+ * decoration. Also, we don't expect any multiassign constructs within the`
	`225`	`+ * list, so there's nothing to do for that. We use this for ROW() and`
	`226`	`+ * VALUES() constructs.`
`225`	`227`	`*`
`226`	`228`	`* exprKind is not enough to tell us whether to allow SetToDefault, so`
`227`	`229`	`* an additional flag is needed for that.`
`@@ -283,9 +285,6 @@ transformExpressionList(ParseState pstate, List exprlist,`
`283`	`285`	`result = lappend(result, e);`
`284`	`286`	`}`
`285`	`287`
`286`		`- /* Shouldn't have any multiassign items here */`
`287`		`- Assert(pstate->p_multiassign_exprs == NIL);`
`288`		`-`
`289`	`288`	`return result;`
`290`	`289`	`}`
`291`	`290`