Re: [PATCH] Include safe-ctype.h after C++ standard headers, to avoid over-poisoning

[Jonathan Wakely <jwakely@redhat.com>]

On 28/09/23 18:37 +0200, Dimitry Andric wrote:
>Ref: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111632
>
>When building gcc's C++ sources against recent libc++, the poisoning of
>the ctype macros due to including safe-ctype.h before including C++
>standard headers such as <list>, <map>, etc, causes many compilation
>errors, similar to:
>
> In file included from /home/dim/src/gcc/master/gcc/gensupport.cc:23:
> In file included from /home/dim/src/gcc/master/gcc/system.h:233:
> In file included from /usr/include/c++/v1/vector:321:
> In file included from
> /usr/include/c++/v1/__format/formatter_bool.h:20:
> In file included from
> /usr/include/c++/v1/__format/formatter_integral.h:32:
> In file included from /usr/include/c++/v1/locale:202:
> /usr/include/c++/v1/__locale:546:5: error: '__abi_tag__' attribute
> only applies to structs, variables, functions, and namespaces
>   546 |     _LIBCPP_INLINE_VISIBILITY
>       |     ^
> /usr/include/c++/v1/__config:813:37: note: expanded from macro
> '_LIBCPP_INLINE_VISIBILITY'
>   813 | #  define _LIBCPP_INLINE_VISIBILITY _LIBCPP_HIDE_FROM_ABI
>       |                                     ^
> /usr/include/c++/v1/__config:792:26: note: expanded from macro
> '_LIBCPP_HIDE_FROM_ABI'
>   792 |
>   __attribute__((__abi_tag__(_LIBCPP_TOSTRING(
> _LIBCPP_VERSIONED_IDENTIFIER))))
>       |                          ^
> In file included from /home/dim/src/gcc/master/gcc/gensupport.cc:23:
> In file included from /home/dim/src/gcc/master/gcc/system.h:233:
> In file included from /usr/include/c++/v1/vector:321:
> In file included from
> /usr/include/c++/v1/__format/formatter_bool.h:20:
> In file included from
> /usr/include/c++/v1/__format/formatter_integral.h:32:
> In file included from /usr/include/c++/v1/locale:202:
> /usr/include/c++/v1/__locale:547:37: error: expected ';' at end of
> declaration list
>   547 |     char_type toupper(char_type __c) const
>       |                                     ^
> /usr/include/c++/v1/__locale:553:48: error: too many arguments
> provided to function-like macro invocation
>   553 |     const char_type* toupper(char_type* __low, const
>   char_type* __high) const
>       |                                                ^
> /home/dim/src/gcc/master/gcc/../include/safe-ctype.h:146:9: note:
> macro 'toupper' defined here
>   146 | #define toupper(c) do_not_use_toupper_with_safe_ctype
>       |         ^
>
>This is because libc++ uses different transitive includes than
>libstdc++, and some of those transitive includes pull in various ctype
>declarations (typically via <locale>).
>
>There was already a special case for including <string> before
>safe-ctype.h, so move the rest of the C++ standard header includes to
>the same location, to fix the problem.

I can't approve this either, but FWIW it looks good to me.


>Signed-off-by: Dimitry Andric <dimitry@andric.com>
>---
>gcc/system.h | 39 ++++++++++++++++++---------------------
>1 file changed, 18 insertions(+), 21 deletions(-)
>
>diff --git a/gcc/system.h b/gcc/system.h
>index e924152ad4c..7a516b11438 100644
>--- a/gcc/system.h
>+++ b/gcc/system.h
>@@ -194,27 +194,8 @@ extern int fprintf_unlocked (FILE *, const char *, ...);
>#undef fread_unlocked
>#undef fwrite_unlocked
>
>-/* Include <string> before "safe-ctype.h" to avoid GCC poisoning
>-   the ctype macros through safe-ctype.h */
>-
>-#ifdef __cplusplus
>-#ifdef INCLUDE_STRING
>-# include <string>
>-#endif
>-#endif
>-
>-/* There are an extraordinary number of issues with <ctype.h>.
>-   The last straw is that it varies with the locale.  Use libiberty's
>-   replacement instead.  */
>-#include "safe-ctype.h"
>-
>-#include <sys/types.h>
>-
>-#include <errno.h>
>-
>-#if !defined (errno) && defined (HAVE_DECL_ERRNO) && !HAVE_DECL_ERRNO
>-extern int errno;
>-#endif
>+/* Include C++ standard headers before "safe-ctype.h" to avoid GCC
>+   poisoning the ctype macros through safe-ctype.h */
>
>#ifdef __cplusplus
>#if defined (INCLUDE_ALGORITHM) || !defined (HAVE_SWAP_IN_UTILITY)
>@@ -229,6 +210,9 @@ extern int errno;
>#ifdef INCLUDE_SET
># include <set>
>#endif
>+#ifdef INCLUDE_STRING
>+# include <string>
>+#endif
>#ifdef INCLUDE_VECTOR
># include <vector>
>#endif
>@@ -245,6 +229,19 @@ extern int errno;
># include <type_traits>
>#endif
>
>+/* There are an extraordinary number of issues with <ctype.h>.
>+   The last straw is that it varies with the locale.  Use libiberty's
>+   replacement instead.  */
>+#include "safe-ctype.h"
>+
>+#include <sys/types.h>
>+
>+#include <errno.h>
>+
>+#if !defined (errno) && defined (HAVE_DECL_ERRNO) && !HAVE_DECL_ERRNO
>+extern int errno;
>+#endif
>+
>/* Some of glibc's string inlines cause warnings.  Plus we'd rather
>   rely on (and therefore test) GCC's string builtins.  */
>#define __NO_STRING_INLINES