fix #26112: update variable kinds in isPartOf to include skResult (#26114)

fix #26112

compiler/aliases.nim

@@ -168,7 +168,7 @@ proc isPartOf*(a, b: PNode; flags: set[PartFlag] = {}): TAnalysisResult =
   if a.kind == b.kind:
     case a.kind
     of nkSym:
-      const varKinds = {skVar, skTemp, skProc, skFunc}
+      const varKinds = {skVar, skTemp, skResult, skProc, skFunc}
       # same symbol: aliasing:
       if a.sym.id == b.sym.id: result = arYes
       elif a.sym.kind in varKinds or b.sym.kind in varKinds:

tests/ccgbugs/t26112.nim

@@ -0,0 +1,35 @@
+discard """
+  matrix: "--mm:refc; --mm:orc"
+  ccodeCheck: "'result.fromScalar = x_p0;'"
+  ccodeCheck: "'result.fromObject = x_p0.fromObject;'"
+  ccodeCheck: "'result.nested.fromNested = x_p0.fromNested;'"
+"""
+
+# bug #26112: unrelated parameters were considered potential aliases of the
+# result location when their types could be contained in the returned object.
+
+type
+  Inner = object
+    fromNested: int
+  P = object
+    fromScalar: int
+    fromObject: int
+    nested: Inner
+
+func fromScalar(x: int): P =
+  P(fromScalar: x)
+
+proc fromObject(x: P): P =
+  P(fromObject: x.fromObject)
+
+func fromNested(x: Inner): P =
+  P(nested: Inner(fromNested: x.fromNested))
+
+proc selfAlias(): P =
+  result.fromScalar = 42
+  result = P(fromScalar: result.fromScalar)
+
+doAssert fromScalar(1).fromScalar == 1
+doAssert fromObject(P(fromObject: 2)).fromObject == 2
+doAssert fromNested(Inner(fromNested: 3)).nested.fromNested == 3
+doAssert selfAlias().fromScalar == 42