[clang] [Clang] fix overload resolution for object parameters with top-level cv-qualifiers in member functions (PR #110435)

[Oleksandr T. via cfe-commits]

https://github.com/a-tarasyuk updated https://github.com/llvm/llvm-project/pull/110435

>From c52634882631a71fad956a70179b480abf13006a Mon Sep 17 00:00:00 2001
From: Oleksandr T <oleksandr.tarasiuk at outlook.com>
Date: Sun, 29 Sep 2024 22:01:38 +0300
Subject: [PATCH 1/2] [Clang] fix overload resolution for object parameters
 with top-level cv-qualifiers in member functions

---
 clang/docs/ReleaseNotes.rst                | 1 +
 clang/lib/Sema/SemaOverload.cpp            | 3 +++
 clang/test/SemaCXX/cxx2b-deducing-this.cpp | 7 +++++++
 3 files changed, 11 insertions(+)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 28c759538f7df6..1bec2838765dab 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -447,6 +447,7 @@ Bug Fixes to C++ Support
 - Fixed an assertion failure in debug mode, and potential crashes in release mode, when
   diagnosing a failed cast caused indirectly by a failed implicit conversion to the type of the constructor parameter.
 - Fixed an assertion failure by adjusting integral to boolean vector conversions (#GH108326)
+- Fixed overload handling for object parameters with top-level cv-qualifiers in explicit member functions (#GH100394)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index 0c1e054f7c30a4..7c40bab70bbe9d 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -1511,6 +1511,9 @@ static bool IsOverloadOrOverrideImpl(Sema &SemaRef, FunctionDecl *New,
       auto NewObjectType = New->getFunctionObjectParameterReferenceType();
       auto OldObjectType = Old->getFunctionObjectParameterReferenceType();
 
+      if (NewObjectType.isConstQualified() != OldObjectType.isConstQualified())
+        return false;
+
       auto IsImplicitWithNoRefQual = [](const CXXMethodDecl *F) {
         return F->getRefQualifier() == RQ_None &&
                !F->isExplicitObjectMemberFunction();
diff --git a/clang/test/SemaCXX/cxx2b-deducing-this.cpp b/clang/test/SemaCXX/cxx2b-deducing-this.cpp
index 63bf92e8d5edd3..5fd02502ce6df4 100644
--- a/clang/test/SemaCXX/cxx2b-deducing-this.cpp
+++ b/clang/test/SemaCXX/cxx2b-deducing-this.cpp
@@ -1073,3 +1073,10 @@ int main() {
   return foo[]; // expected-error {{no viable overloaded operator[] for type 'Foo'}}
 }
 }
+
+namespace GH100394 {
+struct C {
+  void f(this const C);
+  void f() const ;      // ok
+};
+}

>From d377c01f46acf28f1dc74103c6a26df6c0c2e376 Mon Sep 17 00:00:00 2001
From: Oleksandr T <oleksandr.tarasiuk at outlook.com>
Date: Sun, 6 Oct 2024 11:52:48 +0300
Subject: [PATCH 2/2] adjust overload resolution for volatile qualifiers

---
 clang/lib/Sema/SemaOverload.cpp            |  7 +++++--
 clang/test/SemaCXX/cxx2b-deducing-this.cpp | 12 +++++++++---
 2 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index 7c40bab70bbe9d..56705971517cc3 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -1511,8 +1511,11 @@ static bool IsOverloadOrOverrideImpl(Sema &SemaRef, FunctionDecl *New,
       auto NewObjectType = New->getFunctionObjectParameterReferenceType();
       auto OldObjectType = Old->getFunctionObjectParameterReferenceType();
 
-      if (NewObjectType.isConstQualified() != OldObjectType.isConstQualified())
-        return false;
+      if (Old->isExplicitObjectMemberFunction() &&
+          OldObjectType.getQualifiers() != NewObjectType.getQualifiers())
+        return OldObjectType.isConstQualified() &&
+               (NewObjectType.isConstQualified() ||
+                NewObjectType.isVolatileQualified());
 
       auto IsImplicitWithNoRefQual = [](const CXXMethodDecl *F) {
         return F->getRefQualifier() == RQ_None &&
diff --git a/clang/test/SemaCXX/cxx2b-deducing-this.cpp b/clang/test/SemaCXX/cxx2b-deducing-this.cpp
index 5fd02502ce6df4..7dcd63a587c708 100644
--- a/clang/test/SemaCXX/cxx2b-deducing-this.cpp
+++ b/clang/test/SemaCXX/cxx2b-deducing-this.cpp
@@ -1075,8 +1075,14 @@ int main() {
 }
 
 namespace GH100394 {
-struct C {
-  void f(this const C);
-  void f() const ;      // ok
+struct C1 {
+  void f(this const C1);
+  void f() const;        // ok
+};
+
+struct C2 {
+  void f(this const C2);    // expected-note {{previous declaration is here}}
+  void f(this volatile C2); // expected-error {{class member cannot be redeclared}} \
+                            // expected-warning {{volatile-qualified parameter type 'volatile C2' is deprecated}}
 };
 }