[libcxx-commits] [libcxx] [libc++] Protect the libc++ implementation from CUDA SDK's `__noinline__` macro (PR #73838)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libcxx

Author: Dmitri Gribenko (gribozavr)

<details>
<summary>Changes</summary>

The CUDA SDK contains an unfortunate definition for the `__noinline__` macro.

I don't want to quote the code here, but you can find online plenty of information about this macro definition being problematic and creating conflicts for numerous other libraries, for example [on StackOverflow](https://stackoverflow.com/questions/70301375/noinline-macro-conflict-between-glib-and-cuda).

This patch does the following:

* following the existing pattern, it adds `__noinline__` to `_LIBCPP_PUSH_MACROS`, `_LIBCPP_POP_MACROS`, `__undef_macros`, and the test generation script,

* wraps all of `include/__config` in a push/pop bracket pair and includes `__undef_macros` in `__config`.

Macro protection brackets in `__config` are necessary because `__config` uses the `__noinline__` identifier in a `__has_attribute()` preprocessor expression, and that usage suffers from CUDA's definition. This problem can be reproduced with the `system_reserved_names.gen.py` tests if one applies this patch except for the changes to `__undef_macros`.

---
Full diff: https://github.com/llvm/llvm-project/pull/73838.diff


3 Files Affected:

- (modified) libcxx/include/__config (+8-5) 
- (modified) libcxx/include/__undef_macros (+4) 
- (modified) libcxx/test/libcxx/system_reserved_names.gen.py (+3) 


``````````diff
diff --git a/libcxx/include/__config b/libcxx/include/__config
index ee77305162f7fc8..2a77b88562ef614 100644
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -46,6 +46,12 @@
 #    endif
 #  endif
 
+#  define _LIBCPP_PUSH_MACROS _Pragma("push_macro(\"min\")") _Pragma("push_macro(\"max\")") _Pragma("push_macro(\"refresh()\")") _Pragma("push_macro(\"move(int, int)\")") _Pragma("push_macro(\"erase()\")") _Pragma("push_macro(\"__noinline__\")")
+#  define _LIBCPP_POP_MACROS _Pragma("pop_macro(\"min\")") _Pragma("pop_macro(\"max\")") _Pragma("pop_macro(\"refresh()\")") _Pragma("pop_macro(\"move(int, int)\")") _Pragma("pop_macro(\"erase()\")") _Pragma("pop_macro(\"__noinline__\")")
+
+_LIBCPP_PUSH_MACROS
+#  include <__undef_macros>
+
 // The attributes supported by clang are documented at https://clang.llvm.org/docs/AttributeReference.html
 
 // _LIBCPP_VERSION represents the version of libc++, which matches the version of LLVM.
@@ -1208,11 +1214,6 @@ __sanitizer_verify_double_ended_contiguous_container(const void*, const void*, c
 #    define _LIBCPP_ENABLE_CXX20_REMOVED_TYPE_TRAITS
 #  endif // _LIBCPP_ENABLE_CXX20_REMOVED_FEATURES
 
-// clang-format off
-#  define _LIBCPP_PUSH_MACROS _Pragma("push_macro(\"min\")") _Pragma("push_macro(\"max\")") _Pragma("push_macro(\"refresh()\")") _Pragma("push_macro(\"move(int, int)\")") _Pragma("push_macro(\"erase()\")")
-#  define _LIBCPP_POP_MACROS _Pragma("pop_macro(\"min\")") _Pragma("pop_macro(\"max\")") _Pragma("pop_macro(\"refresh()\")") _Pragma("pop_macro(\"move(int, int)\")") _Pragma("pop_macro(\"erase()\")")
-// clang-format on
-
 #  ifndef _LIBCPP_NO_AUTO_LINK
 #    if defined(_LIBCPP_ABI_MICROSOFT) && !defined(_LIBCPP_BUILDING_LIBRARY)
 #      if !defined(_LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS)
@@ -1489,6 +1490,8 @@ __sanitizer_verify_double_ended_contiguous_container(const void*, const void*, c
 #    define _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
 #  endif
 
+_LIBCPP_POP_MACROS
+
 #endif // __cplusplus
 
 #endif // _LIBCPP___CONFIG
diff --git a/libcxx/include/__undef_macros b/libcxx/include/__undef_macros
index 29ab327e1c375ae..885057629d1b831 100644
--- a/libcxx/include/__undef_macros
+++ b/libcxx/include/__undef_macros
@@ -26,3 +26,7 @@
 #ifdef erase
 #  undef erase
 #endif
+
+#ifdef __noinline__
+#  undef __noinline__
+#endif
diff --git a/libcxx/test/libcxx/system_reserved_names.gen.py b/libcxx/test/libcxx/system_reserved_names.gen.py
index 8c4be97897f657e..17ef50568bbb666 100644
--- a/libcxx/test/libcxx/system_reserved_names.gen.py
+++ b/libcxx/test/libcxx/system_reserved_names.gen.py
@@ -158,5 +158,8 @@
 #define erase SYSTEM_RESERVED_NAME
 #define refresh SYSTEM_RESERVED_NAME
 
+// Macros from the CUDA SDKs
+#define __noinline__ __attribute__((noinline))
+
 #include <{header}>
 """)

``````````

</details>


https://github.com/llvm/llvm-project/pull/73838