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

[Sam James <sam@gentoo.org>]

Dimitry Andric <dimitry@andric.com> writes:

> Ping. It would be nice to get this QoL fix in.
>

Yes please - we've been using this in Gentoo since around when it was
first posted. No complaints.

I cannot approve but it looks good to me.

> -Dimitry
>
>> On 28 Sep 2023, at 18:37, Dimitry Andric <dimitry@andric.com> 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.
>> 
>> 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
>> -- 
>> 2.42.0
>>