[PATCH] D89649: Fix __has_unique_object_representations with no_unique_address

[Gabor Bencze via Phabricator via cfe-commits]

gbencze created this revision.
gbencze added reviewers: rsmith, aaron.ballman.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
gbencze requested review of this revision.

Fix incorrect behavior of __has_unique_object_representations when using the no_unique_address attribute.

Based on the bug report: https://bugs.llvm.org/show_bug.cgi?id=47722 <https://bugs.llvm.org/show_bug.cgi?id=47722>


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D89649

Files:
  clang/lib/AST/ASTContext.cpp
  clang/test/SemaCXX/has_unique_object_reps_no_unique_addr.cpp


Index: clang/test/SemaCXX/has_unique_object_reps_no_unique_addr.cpp
===================================================================
--- /dev/null
+++ clang/test/SemaCXX/has_unique_object_reps_no_unique_addr.cpp
@@ -0,0 +1,26 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -fsyntax-only -verify -std=c++2a %s
+//  expected-no-diagnostics
+
+struct Empty {};
+
+struct A {
+  [[no_unique_address]] Empty e;
+  char x;
+};
+
+static_assert(__has_unique_object_representations(A));
+
+struct B {
+  char x;
+  [[no_unique_address]] Empty e;
+};
+
+static_assert(__has_unique_object_representations(B));
+
+struct C {
+  char x;
+  [[no_unique_address]] Empty e1;
+  [[no_unique_address]] Empty e2;
+};
+
+static_assert(!__has_unique_object_representations(C));
Index: clang/lib/AST/ASTContext.cpp
===================================================================
--- clang/lib/AST/ASTContext.cpp
+++ clang/lib/AST/ASTContext.cpp
@@ -2602,9 +2602,12 @@
   }
 
   for (const auto *Field : RD->fields()) {
-    if (!Field->getType()->isReferenceType() &&
-        !Context.hasUniqueObjectRepresentations(Field->getType()))
-      return llvm::None;
+    if (!Field->getType()->isReferenceType()) {
+      if (Field->isZeroSize(Context))
+        continue;
+      else if (!Context.hasUniqueObjectRepresentations(Field->getType()))
+        return llvm::None;
+    }
 
     int64_t FieldSizeInBits =
         Context.toBits(Context.getTypeSizeInChars(Field->getType()));


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