[AST] Update LVal before evaluating lambda decl fields.

[zequanwu]

Summary

PR48582

[rsmith]

clang/lib/AST/ExprConstant.cpp

10032–10033

I don't think this FIXME is appropriate in the new context; just remove it. E here should already be providing the best location information we have.

[zequanwu]

Remove comment.

clang/lib/AST/ExprConstant.cpp

10032–10033

Thanks.

clang/lib/AST/ExprConstant.cpp

assert(NumFields == (size_t)std::distance(E->capture_init_begin(),
          "fields within the closure type");
 
   Result = APValue(APValue::UninitStruct(), /*NumBases*/0, NumFields);
   // Iterate through all the lambda's closure object's fields and initialize
   // them.
   auto *CaptureInitIt = E->capture_init_begin();
   const LambdaCapture *CaptureIt = ClosureClass->captures_begin();
   bool Success = true;
+  const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(ClosureClass);
   for (const auto *Field : ClosureClass->fields()) {
     assert(CaptureInitIt != E->capture_init_end());
     // Get the initializer for this field
     Expr *const CurFieldInit = *CaptureInitIt++;
 
     // If there is no initializer, either this is a VLA or an error has
     // occurred.
     if (!CurFieldInit)
       return Error(E);
 
+    LValue Subobject = This;
+
+    if (!HandleLValueMember(Info, E, Subobject, Field, &Layout))
+      return false;
+
     APValue &FieldVal = Result.getStructField(Field->getFieldIndex());
-    if (!EvaluateInPlace(FieldVal, Info, This, CurFieldInit)) {
+    if (!EvaluateInPlace(FieldVal, Info, Subobject, CurFieldInit)) {
       if (!Info.keepEvaluatingAfterFailure())
         return false;
       Success = false;
     }
     ++CaptureIt;
   }
   return Success;
 }

clang/test/SemaCXX/constant-expression-cxx2a.cpp

 
 constexpr bool destroy_at_test() {
   int n = 0;
   std::destroy(&n);
   std::construct(&n);
   return true;
 }
 static_assert(destroy_at_test());
+
+namespace PR48582 {
+  struct S {
+    void *p = this;
+    constexpr S() {}
+    constexpr S(const S&) {}
+  };
+  constexpr bool b = [a = S(), b = S()] { return a.p == b.p; }();
+  static_assert(!b);
+}