[clang] [Clang] Fix __{add, remove}_pointer in Objective-C++ (PR #123678)

[Nikolas Klauser via cfe-commits]

https://github.com/philnik777 updated https://github.com/llvm/llvm-project/pull/123678

>From 98395fdb573eadea53d7401eec9aac490de3678e Mon Sep 17 00:00:00 2001
From: Nikolas Klauser <nikolasklauser at berlin.de>
Date: Tue, 21 Jan 2025 02:16:02 +0100
Subject: [PATCH] [Clang] Fix __{add,remove}_pointer in Objective-C++

---
 clang/docs/ReleaseNotes.rst          |  8 +++++---
 clang/lib/Sema/SemaType.cpp          |  6 +++---
 clang/test/SemaObjCXX/type-traits.mm | 14 ++++++++++++++
 3 files changed, 22 insertions(+), 6 deletions(-)
 create mode 100644 clang/test/SemaObjCXX/type-traits.mm

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index f6be841035db18..b6d37b8c1cd343 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -310,7 +310,7 @@ C++23 Feature Support
 
 - Extend lifetime of temporaries in mem-default-init for P2718R0. Clang now fully
   supports `P2718R0 Lifetime extension in range-based for loops <https://wg21.link/P2718R0>`_.
-  
+
 - ``__cpp_explicit_this_parameter`` is now defined. (#GH82780)
 
 C++20 Feature Support
@@ -715,7 +715,7 @@ Improvements to Clang's diagnostics
 
 - Clang now diagnoses dangling references for C++20's parenthesized aggregate initialization (#101957).
 
-- Fixed a bug where Clang would not emit ``-Wunused-private-field`` warnings when an unrelated class 
+- Fixed a bug where Clang would not emit ``-Wunused-private-field`` warnings when an unrelated class
   defined a defaulted comparison operator (#GH116270).
 
   .. code-block:: c++
@@ -832,6 +832,8 @@ Bug Fixes to Compiler Builtins
 
 - Fix ``__builtin_source_location`` incorrectly returning wrong column for method chains. (#GH119129)
 
+- The behvaiour of ``__add_pointer`` and ``__remove_pointer`` for Objective-C++'s ``id`` and interfaces has been fixed.
+
 Bug Fixes to Attribute Support
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
@@ -934,7 +936,7 @@ Bug Fixes to C++ Support
 - Fixed an assertion failure caused by invalid default argument substitutions in non-defining
   friend declarations. (#GH113324)
 - Fix a crash caused by incorrect argument position in merging deduced template arguments. (#GH113659)
-- Fixed a parser crash when using pack indexing as a nested name specifier. (#GH119072) 
+- Fixed a parser crash when using pack indexing as a nested name specifier. (#GH119072)
 - Fixed a null pointer dereference issue when heuristically computing ``sizeof...(pack)`` expressions. (#GH81436)
 - Fixed an assertion failure caused by mangled names with invalid identifiers. (#GH112205)
 - Fixed an incorrect lambda scope of generic lambdas that caused Clang to crash when computing potential lambda
diff --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
index 2ccf5a8e1d6f31..10be75c53af08f 100644
--- a/clang/lib/Sema/SemaType.cpp
+++ b/clang/lib/Sema/SemaType.cpp
@@ -1826,7 +1826,8 @@ QualType Sema::BuildPointerType(QualType T,
   if (checkQualifiedFunction(*this, T, Loc, QFK_Pointer))
     return QualType();
 
-  assert(!T->isObjCObjectType() && "Should build ObjCObjectPointerType");
+  if (T->isObjCObjectType())
+    return Context.getObjCObjectPointerType(T);
 
   // In ARC, it is forbidden to build pointers to unqualified pointers.
   if (getLangOpts().ObjCAutoRefCount)
@@ -9806,8 +9807,7 @@ QualType Sema::BuiltinAddPointer(QualType BaseType, SourceLocation Loc) {
 }
 
 QualType Sema::BuiltinRemovePointer(QualType BaseType, SourceLocation Loc) {
-  // We don't want block pointers or ObjectiveC's id type.
-  if (!BaseType->isAnyPointerType() || BaseType->isObjCIdType())
+  if (!BaseType->isAnyPointerType())
     return BaseType;
 
   return BaseType->getPointeeType();
diff --git a/clang/test/SemaObjCXX/type-traits.mm b/clang/test/SemaObjCXX/type-traits.mm
new file mode 100644
index 00000000000000..20cb980e8880bf
--- /dev/null
+++ b/clang/test/SemaObjCXX/type-traits.mm
@@ -0,0 +1,14 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fsyntax-only -verify -std=c++17  %s
+
+// expected-no-diagnostics
+
+ at interface I;
+ at end
+
+static_assert(__is_same(__add_pointer(id), id*));
+static_assert(__is_same(__add_pointer(I), I*));
+
+static_assert(!__is_same(__remove_pointer(id), id));
+static_assert(__is_same(__remove_pointer(id*), id));
+static_assert(__is_same(__remove_pointer(__add_pointer(id)), id));
+static_assert(__is_same(__add_pointer(__remove_pointer(id)), id));