[Clang] Allow __is_nothrow_convertible to be used as an identifier

[philnik777]

__is_nothrow_convertible has been used by libstdc++ previously as an identifier.

[llvmbot]

@llvm/pr-subscribers-clang

Author: Nikolas Klauser (philnik777)

Changes

__is_nothrow_convertible has been used by libstdc++ previously as an identifier.

---

Full diff: https://github.com/llvm/llvm-project/pull/80476.diff

2 Files Affected:

• (modified) clang/lib/Parse/ParseDeclCXX.cpp (+1)
• (added) clang/test/SemaCXX/libstdcxx_is_nothrow_convertible_hack.cpp (+14)

diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index cdbfbb1bc9fff..79928ddb5af59 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -1725,6 +1725,7 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
           tok::kw___is_member_pointer,
           tok::kw___is_nothrow_assignable,
           tok::kw___is_nothrow_constructible,
+          tok::kw___is_nothrow_convertible,
           tok::kw___is_nothrow_destructible,
           tok::kw___is_nullptr,
           tok::kw___is_object,
diff --git a/clang/test/SemaCXX/libstdcxx_is_nothrow_convertible_hack.cpp b/clang/test/SemaCXX/libstdcxx_is_nothrow_convertible_hack.cpp
new file mode 100644
index 0000000000000..9e84f0ab1c081
--- /dev/null
+++ b/clang/test/SemaCXX/libstdcxx_is_nothrow_convertible_hack.cpp
@@ -0,0 +1,14 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fsyntax-only -verify -std=gnu++20 -fms-extensions -Wno-microsoft %s
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fsyntax-only -verify -std=gnu++23 -fms-extensions -Wno-microsoft %s
+
+template <class T, class U>
+struct Same {
+  static constexpr auto value = __is_same(T, U);
+};
+
+template <class T>
+struct __is_nothrow_convertible { // expected-warning{{keyword '__is_nothrow_convertible' will be made available as an identifier for the remainder of the translation unit}}
+  using type = T;
+};
+
+using A = Same<__is_nothrow_convertible<int>::type, __is_nothrow_convertible<int>::type>;

[github-actions]

⚠️ C/C++ code formatter, clang-format found issues in your code. ⚠️

You can test this locally with the following command:

git-clang-format --diff 9cc2122bf5a81f7063c2a32b2cb78c8d615578a1 fb4160b50535fd16951c5261e6c7d91da0cd92b0 -- clang/test/SemaCXX/libstdcxx_is_nothrow_convertible_hack.cpp clang/lib/Parse/ParseDeclCXX.cpp

View the diff from clang-format here.

diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index 79928ddb5a..35b4607bf8 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -1694,64 +1694,32 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
       Tok.isOneOf(
 #define TRANSFORM_TYPE_TRAIT_DEF(_, Trait) tok::kw___##Trait,
 #include "clang/Basic/TransformTypeTraits.def"
-          tok::kw___is_abstract,
-          tok::kw___is_aggregate,
-          tok::kw___is_arithmetic,
-          tok::kw___is_array,
-          tok::kw___is_assignable,
-          tok::kw___is_base_of,
-          tok::kw___is_bounded_array,
-          tok::kw___is_class,
-          tok::kw___is_complete_type,
-          tok::kw___is_compound,
-          tok::kw___is_const,
-          tok::kw___is_constructible,
-          tok::kw___is_convertible,
-          tok::kw___is_convertible_to,
-          tok::kw___is_destructible,
-          tok::kw___is_empty,
-          tok::kw___is_enum,
-          tok::kw___is_floating_point,
-          tok::kw___is_final,
-          tok::kw___is_function,
-          tok::kw___is_fundamental,
-          tok::kw___is_integral,
-          tok::kw___is_interface_class,
-          tok::kw___is_literal,
-          tok::kw___is_lvalue_expr,
-          tok::kw___is_lvalue_reference,
-          tok::kw___is_member_function_pointer,
-          tok::kw___is_member_object_pointer,
-          tok::kw___is_member_pointer,
-          tok::kw___is_nothrow_assignable,
-          tok::kw___is_nothrow_constructible,
-          tok::kw___is_nothrow_convertible,
-          tok::kw___is_nothrow_destructible,
-          tok::kw___is_nullptr,
-          tok::kw___is_object,
-          tok::kw___is_pod,
-          tok::kw___is_pointer,
-          tok::kw___is_polymorphic,
-          tok::kw___is_reference,
-          tok::kw___is_referenceable,
-          tok::kw___is_rvalue_expr,
-          tok::kw___is_rvalue_reference,
-          tok::kw___is_same,
-          tok::kw___is_scalar,
-          tok::kw___is_scoped_enum,
-          tok::kw___is_sealed,
-          tok::kw___is_signed,
-          tok::kw___is_standard_layout,
-          tok::kw___is_trivial,
+          tok::kw___is_abstract, tok::kw___is_aggregate,
+          tok::kw___is_arithmetic, tok::kw___is_array, tok::kw___is_assignable,
+          tok::kw___is_base_of, tok::kw___is_bounded_array, tok::kw___is_class,
+          tok::kw___is_complete_type, tok::kw___is_compound, tok::kw___is_const,
+          tok::kw___is_constructible, tok::kw___is_convertible,
+          tok::kw___is_convertible_to, tok::kw___is_destructible,
+          tok::kw___is_empty, tok::kw___is_enum, tok::kw___is_floating_point,
+          tok::kw___is_final, tok::kw___is_function, tok::kw___is_fundamental,
+          tok::kw___is_integral, tok::kw___is_interface_class,
+          tok::kw___is_literal, tok::kw___is_lvalue_expr,
+          tok::kw___is_lvalue_reference, tok::kw___is_member_function_pointer,
+          tok::kw___is_member_object_pointer, tok::kw___is_member_pointer,
+          tok::kw___is_nothrow_assignable, tok::kw___is_nothrow_constructible,
+          tok::kw___is_nothrow_convertible, tok::kw___is_nothrow_destructible,
+          tok::kw___is_nullptr, tok::kw___is_object, tok::kw___is_pod,
+          tok::kw___is_pointer, tok::kw___is_polymorphic,
+          tok::kw___is_reference, tok::kw___is_referenceable,
+          tok::kw___is_rvalue_expr, tok::kw___is_rvalue_reference,
+          tok::kw___is_same, tok::kw___is_scalar, tok::kw___is_scoped_enum,
+          tok::kw___is_sealed, tok::kw___is_signed,
+          tok::kw___is_standard_layout, tok::kw___is_trivial,
           tok::kw___is_trivially_equality_comparable,
           tok::kw___is_trivially_assignable,
-          tok::kw___is_trivially_constructible,
-          tok::kw___is_trivially_copyable,
-          tok::kw___is_unbounded_array,
-          tok::kw___is_union,
-          tok::kw___is_unsigned,
-          tok::kw___is_void,
-          tok::kw___is_volatile,
+          tok::kw___is_trivially_constructible, tok::kw___is_trivially_copyable,
+          tok::kw___is_unbounded_array, tok::kw___is_union,
+          tok::kw___is_unsigned, tok::kw___is_void, tok::kw___is_volatile,
           tok::kw___reference_binds_to_temporary,
           tok::kw___reference_constructs_from_temporary))
     // GNU libstdc++ 4.2 and libc++ use certain intrinsic names as the