[libc++] __uglify [[clang::noescape]]

[frederick-vs-ja]

Identifiers clang and noescape are not reserved by the C++ standard, so perhaps we need to use the equivalent reserved forms.

Also changes the occurrences of that attribute to a macro, following the convention for [[_Clang::__lifetimebound__]].

Addresses #91651 (comment).

[llvmbot]

@llvm/pr-subscribers-libcxx

Author: A. Jiang (frederick-vs-ja)

Changes

Identifiers clang and noescape are not reserved by the C++ standard, so perhaps we need to use the equivalent reserved forms.

Also changes the occurrences of that attribute to a macro, following the convention for [[_Clang::__lifetimebound__]].

Addresses #91651 (comment).

---

Full diff: https://github.com/llvm/llvm-project/pull/113280.diff

4 Files Affected:

• (modified) libcxx/include/__charconv/from_chars_floating_point.h (+3-3)
• (modified) libcxx/include/__config (+6)
• (modified) libcxx/src/charconv.cpp (+3-3)
• (modified) libcxx/test/libcxx/system_reserved_names.gen.py (+5)

diff --git a/libcxx/include/__charconv/from_chars_floating_point.h b/libcxx/include/__charconv/from_chars_floating_point.h
index 2860b0e8da83af..5cd3fc4a41ea1d 100644
--- a/libcxx/include/__charconv/from_chars_floating_point.h
+++ b/libcxx/include/__charconv/from_chars_floating_point.h
@@ -37,13 +37,13 @@ struct __from_chars_result {
 
 template <class _Fp>
 _LIBCPP_EXPORTED_FROM_ABI __from_chars_result<_Fp> __from_chars_floating_point(
-    [[clang::noescape]] const char* __first, [[clang::noescape]] const char* __last, chars_format __fmt);
+    _LIBCPP_NOESCAPE const char* __first, _LIBCPP_NOESCAPE const char* __last, chars_format __fmt);
 
 extern template __from_chars_result<float> __from_chars_floating_point(
-    [[clang::noescape]] const char* __first, [[clang::noescape]] const char* __last, chars_format __fmt);
+    _LIBCPP_NOESCAPE const char* __first, _LIBCPP_NOESCAPE const char* __last, chars_format __fmt);
 
 extern template __from_chars_result<double> __from_chars_floating_point(
-    [[clang::noescape]] const char* __first, [[clang::noescape]] const char* __last, chars_format __fmt);
+    _LIBCPP_NOESCAPE const char* __first, _LIBCPP_NOESCAPE const char* __last, chars_format __fmt);
 
 template <class _Fp>
 _LIBCPP_HIDE_FROM_ABI from_chars_result
diff --git a/libcxx/include/__config b/libcxx/include/__config
index fcba56f7e3d5b1..fca1a01851e81e 100644
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -1167,6 +1167,12 @@ typedef __char32_t char32_t;
 #    define _LIBCPP_LIFETIMEBOUND
 #  endif
 
+#  if __has_cpp_attribute(_Clang::__noescape__)
+#    define _LIBCPP_NOESCAPE [[_Clang::__noescape__]]
+#  else
+#    define _LIBCPP_NOESCAPE
+#  endif
+
 #  if __has_attribute(__nodebug__)
 #    define _LIBCPP_NODEBUG __attribute__((__nodebug__))
 #  else
diff --git a/libcxx/src/charconv.cpp b/libcxx/src/charconv.cpp
index 3fe0afec0e283c..5e8cb7d97703b4 100644
--- a/libcxx/src/charconv.cpp
+++ b/libcxx/src/charconv.cpp
@@ -77,13 +77,13 @@ to_chars_result to_chars(char* __first, char* __last, long double __value, chars
 
 template <class _Fp>
 __from_chars_result<_Fp> __from_chars_floating_point(
-    [[clang::noescape]] const char* __first, [[clang::noescape]] const char* __last, chars_format __fmt) {
+    _LIBCPP_NOESCAPE const char* __first, _LIBCPP_NOESCAPE const char* __last, chars_format __fmt) {
   return std::__from_chars_floating_point_impl<_Fp>(__first, __last, __fmt);
 }
 
 template __from_chars_result<float> __from_chars_floating_point(
-    [[clang::noescape]] const char* __first, [[clang::noescape]] const char* __last, chars_format __fmt);
+    _LIBCPP_NOESCAPE const char* __first, _LIBCPP_NOESCAPE const char* __last, chars_format __fmt);
 
 template __from_chars_result<double> __from_chars_floating_point(
-    [[clang::noescape]] const char* __first, [[clang::noescape]] const char* __last, chars_format __fmt);
+    _LIBCPP_NOESCAPE const char* __first, _LIBCPP_NOESCAPE const char* __last, chars_format __fmt);
 _LIBCPP_END_NAMESPACE_STD
diff --git a/libcxx/test/libcxx/system_reserved_names.gen.py b/libcxx/test/libcxx/system_reserved_names.gen.py
index e29e7a2cdd6144..f3ded81cb0a2d6 100644
--- a/libcxx/test/libcxx/system_reserved_names.gen.py
+++ b/libcxx/test/libcxx/system_reserved_names.gen.py
@@ -154,6 +154,11 @@
 #define Xp SYSTEM_RESERVED_NAME
 #define Xs SYSTEM_RESERVED_NAME
 
+// These attribute-tokens are not reserved, so the user can macro-define them.
+#define clang SYSTEM_RESERVED_NAME
+#define lifetimebound SYSTEM_RESERVED_NAME
+#define noescape SYSTEM_RESERVED_NAME
+
 // The classic Windows min/max macros
 #define min SYSTEM_RESERVED_NAME
 #define max SYSTEM_RESERVED_NAME

[ldionne]

Oops... I must had ignored the following comments. @ldionne are you also working on such a macro? Perhaps this PR should be closed if so.

No, I don't have a patch yet. I just wanted to add documentation that can reference that macro.