Fix assignment to array of domain over composite, redux.

tglsfdc · tglsfdc · commit c53ed26ea46e · 2023-04-15T12:01:39.000-04:00
Commit 3e310d8 taught isAssignmentIndirectionExpr() to look through CoerceToDomain nodes. That's not sufficient, because since commit 04fe805 it's been possible for the planner to simplify CoerceToDomain to RelabelType when the domain has no constraints to enforce. So we need to look through RelabelType too. Per bug #17897 from Alexander Lakhin. Although 3e310d8 was back-patched to v11, it seems sufficient to apply this change to v12 and later, since 04fe805 came in in v12. Dmitry Dolgov Discussion: https://postgr.es/m/17897-4216c546c3874044@postgresql.org
diff --git a/src/backend/executor/execExpr.c b/src/backend/executor/execExpr.c
@@ -3131,8 +3131,8 @@ ExecInitSubscriptingRef(ExprEvalStep *scratch, SubscriptingRef *sbsref,
  * trees in which each level of assignment has its own CaseTestExpr, and the
  * recursive structure appears within the newvals or refassgnexpr field.
  * There is an exception, though: if the array is an array-of-domain, we will
- * have a CoerceToDomain as the refassgnexpr, and we need to be able to look
- * through that.
+ * have a CoerceToDomain or RelabelType as the refassgnexpr, and we need to
+ * be able to look through that.
  */
 static bool
 isAssignmentIndirectionExpr(Expr *expr)
@@ -3159,6 +3159,12 @@ isAssignmentIndirectionExpr(Expr *expr)
 
 		return isAssignmentIndirectionExpr(cd->arg);
 	}
+	else if (IsA(expr, RelabelType))
+	{
+		RelabelType *r = (RelabelType *) expr;
+
+		return isAssignmentIndirectionExpr(r->arg);
+	}
 	return false;
 }
 
diff --git a/src/test/regress/expected/domain.out b/src/test/regress/expected/domain.out
@@ -556,6 +556,15 @@ table dcomptable;
  {"(1,5)"}
 (1 row)
 
+-- if there's no constraints, a different code path is taken:
+alter domain dcomptype drop constraint dcomptype_check;
+update dcomptable set f1[1].cf1 = -1;  -- now ok
+table dcomptable;
+     f1     
+------------
+ {"(-1,5)"}
+(1 row)
+
 drop table dcomptable;
 drop type comptype cascade;
 NOTICE:  drop cascades to type dcomptype
diff --git a/src/test/regress/sql/domain.sql b/src/test/regress/sql/domain.sql
@@ -288,6 +288,10 @@ table dcomptable;
 update dcomptable set f1[1].cf1 = -1;  -- fail
 update dcomptable set f1[1].cf1 = 1;
 table dcomptable;
+-- if there's no constraints, a different code path is taken:
+alter domain dcomptype drop constraint dcomptype_check;
+update dcomptable set f1[1].cf1 = -1;  -- now ok
+table dcomptable;
 
 drop table dcomptable;
 drop type comptype cascade;
