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@ldionne ldionne commented Apr 9, 2024

As reported in #86843, we must have #pragma GCC system_header before we use #include_next, otherwise the compiler may not understand that we're in a system header and may issue a diagnostic for our usage of

As reported in llvm#86843, we must have #pragma GCC system_header before
we use #include_next, otherwise the compiler may not understand that
we're in a system header and may issue a diagnostic for our usage of
@ldionne ldionne requested a review from a team as a code owner April 9, 2024 23:49
@llvmbot llvmbot added the libc++ libc++ C++ Standard Library. Not GNU libstdc++. Not libc++abi. label Apr 9, 2024
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llvmbot commented Apr 9, 2024

@llvm/pr-subscribers-libcxx

Author: Louis Dionne (ldionne)

Changes

As reported in #86843, we must have #pragma GCC system_header before we use #include_next, otherwise the compiler may not understand that we're in a system header and may issue a diagnostic for our usage of


Full diff: https://github.com/llvm/llvm-project/pull/88214.diff

1 Files Affected:

  • (modified) libcxx/include/stddef.h (+4-4)
diff --git a/libcxx/include/stddef.h b/libcxx/include/stddef.h
index 470b5408336c6d..1583e78e3739ba 100644
--- a/libcxx/include/stddef.h
+++ b/libcxx/include/stddef.h
@@ -26,6 +26,10 @@
 
 #include <__config>
 
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
 // Note: This include is outside of header guards because we sometimes get included multiple times
 //       with different defines and the underlying <stddef.h> will know how to deal with that.
 #include_next <stddef.h>
@@ -33,10 +37,6 @@
 #ifndef _LIBCPP_STDDEF_H
 #  define _LIBCPP_STDDEF_H
 
-#  if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-#    pragma GCC system_header
-#  endif
-
 #  ifdef __cplusplus
 typedef decltype(nullptr) nullptr_t;
 #  endif

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LGTM! I did a spot check of our headers and this seems a one off, so I don't think we need to add comments to the location of pragma GCC system_header.

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@ldionne like @nico said, we merged the original change to llvm 18 so now we need this one too. 🙄

@nico nico merged commit 3c4b673 into llvm:main Apr 11, 2024
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nico commented Apr 11, 2024

@ian-twilightcoder Do you want to create the merge ticket?

@ldionne ldionne deleted the review/fix-include-next branch April 11, 2024 17:48
@ldionne ldionne added this to the LLVM 18.X Release milestone Apr 11, 2024
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ldionne commented Apr 11, 2024

/cherry-pick 3c4b673

llvmbot pushed a commit to llvmbot/llvm-project that referenced this pull request Apr 11, 2024
As reported in llvm#86843, we must have #pragma GCC system_header before we
use #include_next, otherwise the compiler may not understand that we're
in a system header and may issue a diagnostic for our usage of

(cherry picked from commit 3c4b673)
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llvmbot commented Apr 11, 2024

/pull-request #88419

llvmbot pushed a commit to llvmbot/llvm-project that referenced this pull request Apr 11, 2024
As reported in llvm#86843, we must have #pragma GCC system_header before we
use #include_next, otherwise the compiler may not understand that we're
in a system header and may issue a diagnostic for our usage of

(cherry picked from commit 3c4b673)
tstellar pushed a commit to llvmbot/llvm-project that referenced this pull request Apr 16, 2024
As reported in llvm#86843, we must have #pragma GCC system_header before we
use #include_next, otherwise the compiler may not understand that we're
in a system header and may issue a diagnostic for our usage of

(cherry picked from commit 3c4b673)
@pointhex pointhex mentioned this pull request May 7, 2024
Tedlion pushed a commit to Tedlion/llvm-project that referenced this pull request Jun 15, 2025
As reported in llvm#86843, we must have #pragma GCC system_header before we
use #include_next, otherwise the compiler may not understand that we're
in a system header and may issue a diagnostic for our usage of

(cherry picked from commit 3c4b673)
Tedlion pushed a commit to Tedlion/llvm-project that referenced this pull request Jun 15, 2025
As reported in llvm#86843, we must have #pragma GCC system_header before we
use #include_next, otherwise the compiler may not understand that we're
in a system header and may issue a diagnostic for our usage of

(cherry picked from commit 3c4b673)
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