Fix regression with UPDATEs on a complex path with rewrite

This was introduced as a regression in 6.x by #7265, which eliminated
the use of a separate standalone subject_path_id to represent the
object being updated in a rewrite.

The method used for picking the the subject_path_id used when
compiling the rewrites was unsound, though, and only worked in the
simple case.

Fix this by passing in the path_id of the update expression, so that
it always matches.

(If this doesn't make sense to people, we could revert #7265 instead.)

Fixes #8444

Author: msullivan

edb/edgeql/compiler/viewgen.py

@@ -1018,7 +1018,8 @@ def _compile_rewrites(
 
     def get_anchors(stype: s_objtypes.ObjectType) -> RewriteAnchors:
         if stype not in anchors:
-            anchors[stype] = prepare_rewrite_anchors(stype, r_ctx, s_ctx, ctx)
+            anchors[stype] = prepare_rewrite_anchors(
+                stype, ir_set.path_id, r_ctx, s_ctx, ctx)
         return anchors[stype]
 
     rewrites = _compile_rewrites_for_stype(
@@ -1270,17 +1271,14 @@ class RewriteAnchors:
 
 def prepare_rewrite_anchors(
     stype: s_objtypes.ObjectType,
+    subject_path_id: irast.PathId,
     r_ctx: RewriteContext,
     s_ctx: ShapeContext,
     ctx: context.ContextLevel,
 ) -> RewriteAnchors:
     schema = ctx.env.schema
 
     # init set for __subject__
-    subject_path_id = irast.PathId.from_type(
-        schema, stype,
-        namespace=ctx.path_id_namespace, env=ctx.env,
-    )
     subject_set = setgen.class_set(
         stype, path_id=subject_path_id, ctx=ctx
     )

tests/test_edgeql_rewrites.py

@@ -24,7 +24,7 @@
 from edb.testbase import server as tb
 
 
-class TestRewrites(tb.QueryTestCase):
+class TestRewrites(tb.DDLTestCase):
 
     SCHEMA = os.path.join(os.path.dirname(__file__), 'schemas', 'movies.esdl')
     # Setting up some rewrites makes the tests run a bit faster
@@ -1108,3 +1108,52 @@ async def test_edgeql_rewrites_29(self):
             update Project set { name := '## redacted ##' }
             '''
         )
+
+    async def test_edgeql_rewrites_30(self):
+        await self.con.execute('''
+            insert Document { name := '1' };
+            insert Document { name := '2' };
+            insert Document { name := '3' };
+        ''')
+
+        await self.con.execute('''
+            with H := ( x := (select Document filter .name = '1') )
+            update H.x set { text := 'full' };
+        ''')
+        await self.con.execute('''
+            with H := { x := (select Document filter .name = '1') }
+            update H.x set { text := 'full' };
+        ''')
+        await self.con.execute('''
+            with H := { x := (select Document filter .name = '1' limit 1) }
+            update H.x set { text := 'full' };
+        ''')
+
+    async def test_edgeql_rewrites_triggers_01(self):
+        await self.con.execute('''
+            create type Pidgeon {
+                create required link hole: Document;
+                create trigger set_hole_full
+                    after insert
+                    for each do (update
+                        __new__.hole
+                    set {
+                        text := 'full'
+                    });
+            };
+        ''')
+
+        await self.con.execute('''
+            insert Document { name := '1' };
+            insert Document { name := '2' };
+            insert Document { name := '3' };
+        ''')
+
+        # A 6.0 regression (#8444)
+        await self.con.execute('''
+            insert Pidgeon {
+                hole := (
+                    (select Document filter .name = '1' limit 1)
+                ),
+            };
+        ''')