[libcxx-commits] [libcxx] [libc++] Remove explicit mentions of __need_FOO macros (PR #119025)
Louis Dionne via libcxx-commits
libcxx-commits at lists.llvm.org
Fri Dec 6 12:26:22 PST 2024
https://github.com/ldionne created https://github.com/llvm/llvm-project/pull/119025
This change has a long history. It was first attempted naively in https://reviews.llvm.org/D131425, which didn't work because we broke the ability for code to include e.g. <stdio.h> multiple times and get different definitions based on the pre-defined macros.
However, in #86843 we managed to simplify <stddef.h> by including the underlying system header outside of any include guards, which worked.
This patch applies the same simplification we did to <stddef.h> to the other headers that currently mention __need_FOO macros explicitly.
>From 9d78f8338e106b1572bae9c2237d9b2c742ac179 Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2 at gmail.com>
Date: Fri, 6 Dec 2024 15:20:55 -0500
Subject: [PATCH] [libc++] Remove explicit mentions of __need_FOO macros
This change has a long history. It was first attempted naively in
https://reviews.llvm.org/D131425, which didn't work because we broke
the ability for code to include e.g. <stdio.h> multiple times and get
different definitions based on the pre-defined macros.
However, in #86843 we managed to simplify <stddef.h> by including
the underlying system header outside of any include guards, which
worked.
This patch applies the same simplification we did to <stddef.h> to
the other headers that currently mention __need_FOO macros explicitly.
---
libcxx/include/module.modulemap | 8 +++----
libcxx/include/stdio.h | 29 +++++++++++------------
libcxx/include/stdlib.h | 31 ++++++++++++-------------
libcxx/include/wchar.h | 41 ++++++++++++++++-----------------
4 files changed, 53 insertions(+), 56 deletions(-)
diff --git a/libcxx/include/module.modulemap b/libcxx/include/module.modulemap
index ed2b7fb1921642..db36ad5bc69592 100644
--- a/libcxx/include/module.modulemap
+++ b/libcxx/include/module.modulemap
@@ -2265,15 +2265,15 @@ module std_stdbool_h [system] {
textual header "stdbool.h"
}
module std_stddef_h [system] {
- // <stddef.h>'s __need_* macros require textual inclusion.
+ // <stddef.h> supports being included multiple times with different pre-defined macros
textual header "stddef.h"
}
module std_stdio_h [system] {
- // <stdio.h>'s __need_* macros require textual inclusion.
+ // <stdio.h> supports being included multiple times with different pre-defined macros
textual header "stdio.h"
}
module std_stdlib_h [system] {
- // <stdlib.h>'s __need_* macros require textual inclusion.
+ // <stdlib.h> supports being included multiple times with different pre-defined macros
textual header "stdlib.h"
}
module std_string_h [system] {
@@ -2289,7 +2289,7 @@ module std_uchar_h [system] {
export *
}
module std_wchar_h [system] {
- // <wchar.h>'s __need_* macros require textual inclusion.
+ // <wchar.h> supports being included multiple times with different pre-defined macros
textual header "wchar.h"
}
module std_wctype_h [system] {
diff --git a/libcxx/include/stdio.h b/libcxx/include/stdio.h
index 3aa559393f1853..2516e9b78342d6 100644
--- a/libcxx/include/stdio.h
+++ b/libcxx/include/stdio.h
@@ -7,17 +7,6 @@
//
//===----------------------------------------------------------------------===//
-#if defined(__need_FILE) || defined(__need___FILE)
-
-# if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-# pragma GCC system_header
-# endif
-
-# include_next <stdio.h>
-
-#elif !defined(_LIBCPP_STDIO_H)
-# define _LIBCPP_STDIO_H
-
/*
stdio.h synopsis
@@ -98,11 +87,21 @@ int ferror(FILE* stream);
void perror(const char* s);
*/
-# include <__config>
+#include <__config>
-# if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-# pragma GCC system_header
-# endif
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+# pragma GCC system_header
+#endif
+
+// The inclusion of the system's <stdio.h> is intentionally done once outside of any include
+// guards because some code expects to be able to include the underlying system header multiple
+// times to get different definitions based on the macros that are set before inclusion.
+#if __has_include_next(<stdio.h>)
+# include_next <stdio.h>
+#endif
+
+#ifndef _LIBCPP_STDIO_H
+# define _LIBCPP_STDIO_H
# if __has_include_next(<stdio.h>)
# include_next <stdio.h>
diff --git a/libcxx/include/stdlib.h b/libcxx/include/stdlib.h
index 358b10c0392a52..84f8882be41dbb 100644
--- a/libcxx/include/stdlib.h
+++ b/libcxx/include/stdlib.h
@@ -7,17 +7,6 @@
//
//===----------------------------------------------------------------------===//
-#if defined(__need_malloc_and_calloc)
-
-# if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-# pragma GCC system_header
-# endif
-
-# include_next <stdlib.h>
-
-#elif !defined(_LIBCPP_STDLIB_H)
-# define _LIBCPP_STDLIB_H
-
/*
stdlib.h synopsis
@@ -84,11 +73,21 @@ void *aligned_alloc(size_t alignment, size_t size); // C11
*/
-# include <__config>
+#include <__config>
-# if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-# pragma GCC system_header
-# endif
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+# pragma GCC system_header
+#endif
+
+// The inclusion of the system's <stdlib.h> is intentionally done once outside of any include
+// guards because some code expects to be able to include the underlying system header multiple
+// times to get different definitions based on the macros that are set before inclusion.
+#if __has_include_next(<stdlib.h>)
+# include_next <stdlib.h>
+#endif
+
+#if !defined(_LIBCPP_STDLIB_H)
+# define _LIBCPP_STDLIB_H
# if __has_include_next(<stdlib.h>)
# include_next <stdlib.h>
@@ -146,6 +145,6 @@ inline _LIBCPP_HIDE_FROM_ABI lldiv_t div(long long __x, long long __y) _NOEXCEPT
# endif
# endif // _LIBCPP_MSVCRT
} // extern "C++"
-# endif // __cplusplus
+# endif // __cplusplus
#endif // _LIBCPP_STDLIB_H
diff --git a/libcxx/include/wchar.h b/libcxx/include/wchar.h
index b7cd5d7fc62cde..66d7f8f8de8603 100644
--- a/libcxx/include/wchar.h
+++ b/libcxx/include/wchar.h
@@ -7,17 +7,6 @@
//
//===----------------------------------------------------------------------===//
-#if defined(__need_wint_t) || defined(__need_mbstate_t)
-
-# if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-# pragma GCC system_header
-# endif
-
-# include_next <wchar.h>
-
-#elif !defined(_LIBCPP_WCHAR_H)
-# define _LIBCPP_WCHAR_H
-
/*
wchar.h synopsis
@@ -105,23 +94,33 @@ size_t wcsrtombs(char* restrict dst, const wchar_t** restrict src, size_t len,
*/
-# include <__config>
-# include <stddef.h>
+#include <__config>
-# if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-# pragma GCC system_header
-# endif
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+# pragma GCC system_header
+#endif
// We define this here to support older versions of glibc <wchar.h> that do
// not define this for clang.
-# ifdef __cplusplus
-# define __CORRECT_ISO_CPP_WCHAR_H_PROTO
-# endif
+#if defined(__cplusplus) && !defined(__CORRECT_ISO_CPP_WCHAR_H_PROTO)
+# define __CORRECT_ISO_CPP_WCHAR_H_PROTO
+#endif
+
+// The inclusion of the system's <wchar.h> is intentionally done once outside of any include
+// guards because some code expects to be able to include the underlying system header multiple
+// times to get different definitions based on the macros that are set before inclusion.
+#if __has_include_next(<wchar.h>)
+# include_next <wchar.h>
+#endif
+
+#ifndef _LIBCPP_WCHAR_H
+# define _LIBCPP_WCHAR_H
+
+# include <__mbstate_t.h> // provide mbstate_t
+# include <stddef.h> // provide size_t
# if __has_include_next(<wchar.h>)
# include_next <wchar.h>
-# else
-# include <__mbstate_t.h> // make sure we have mbstate_t regardless of the existence of <wchar.h>
# endif
// Determine whether we have const-correct overloads for wcschr and friends.
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