[clang] [clang][MSExtentions] Fix invalid overload failure about the loss of `__unaligned` qualifier (PR #65248)

[Takuya Shimizu via cfe-commits]

https://github.com/hazohelet updated https://github.com/llvm/llvm-project/pull/65248:

>From eee4c3aee9350be51c9333f284810ffebd9d1663 Mon Sep 17 00:00:00 2001
From: Takuya Shimizu <shimizu2486 at gmail.com>
Date: Mon, 4 Sep 2023 16:23:00 +0900
Subject: [PATCH 1/3] [clang][MSExtentions] Fix invalid overload failure about
 the loss of `__unaligned` qualifier

Loss of `__unaligned` qualifier does not invalidate overload
candidates.
This fixes a regression reported in https://reviews.llvm.org/D153690
---
 clang/lib/Sema/SemaOverload.cpp            |  8 +++++---
 clang/test/SemaCXX/MicrosoftExtensions.cpp | 11 +++++++++++
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index 5d0299dfa752f92..9833d0d312186b6 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -5557,9 +5557,11 @@ TryObjectArgumentInitialization(Sema &S, SourceLocation Loc, QualType FromType,
 
   // First check the qualifiers.
   QualType FromTypeCanon = S.Context.getCanonicalType(FromType);
-  if (ImplicitParamType.getCVRQualifiers()
-                                    != FromTypeCanon.getLocalCVRQualifiers() &&
-      !ImplicitParamType.isAtLeastAsQualifiedAs(FromTypeCanon)) {
+  // MSVC ignores __unaligned qualifier for overload candidates; do the same.
+  if (ImplicitParamType.getCVRQualifiers() !=
+          FromTypeCanon.getLocalCVRQualifiers() &&
+      !ImplicitParamType.isAtLeastAsQualifiedAs(
+          withoutUnaligned(S.Context, FromTypeCanon))) {
     ICS.setBad(BadConversionSequence::bad_qualifiers,
                FromType, ImplicitParamType);
     return ICS;
diff --git a/clang/test/SemaCXX/MicrosoftExtensions.cpp b/clang/test/SemaCXX/MicrosoftExtensions.cpp
index 960030d44f0c155..71618048014cc74 100644
--- a/clang/test/SemaCXX/MicrosoftExtensions.cpp
+++ b/clang/test/SemaCXX/MicrosoftExtensions.cpp
@@ -589,6 +589,17 @@ namespace PR42089 {
   __attribute__((nothrow)) void S::Bar(){}
 }
 
+namespace UnalignedConv {
+struct S {
+  bool operator==(int) const;
+};
+
+int func() {
+  S __unaligned s;
+  return s == 42;
+}
+}
+
 #elif TEST2
 
 // Check that __unaligned is not recognized if MS extensions are not enabled

>From d76263dacae363fe8b82e40babada9fa50a1f830 Mon Sep 17 00:00:00 2001
From: Takuya Shimizu <shimizu2486 at gmail.com>
Date: Tue, 5 Sep 2023 01:09:47 +0900
Subject: [PATCH 2/3] Dummy commit to trigger CI build/test

---
 clang/test/SemaCXX/MicrosoftExtensions.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/clang/test/SemaCXX/MicrosoftExtensions.cpp b/clang/test/SemaCXX/MicrosoftExtensions.cpp
index 71618048014cc74..7286217b1644f3e 100644
--- a/clang/test/SemaCXX/MicrosoftExtensions.cpp
+++ b/clang/test/SemaCXX/MicrosoftExtensions.cpp
@@ -600,6 +600,7 @@ int func() {
 }
 }
 
+
 #elif TEST2
 
 // Check that __unaligned is not recognized if MS extensions are not enabled

>From 4f184b9b6f2f2e236fea2c7d8e358cd4779ea1ed Mon Sep 17 00:00:00 2001
From: Takuya Shimizu <shimizu2486 at gmail.com>
Date: Tue, 5 Sep 2023 11:32:28 +0900
Subject: [PATCH 3/3] Add release note

---
 clang/docs/ReleaseNotes.rst | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index c6d2c3466a09622..dbb719eb338dc63 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -211,6 +211,8 @@ Bug Fixes in This Version
 - Clang now reports ``-Wformat`` for bool value and char specifier confusion
   in scanf. Fixes
   (`#64987 <https://github.com/llvm/llvm-project/issues/64987>`_)
+- Clang no longer considers the loss of ``__unaligned`` qualifier from objects as
+  an invalid conversion during method function overload resolution.
 
 Bug Fixes to Compiler Builtins
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^