Re: [PATCH] stdio: Move include of bits/stdio-ldbl.h before bits/stdio.h

[John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>]

Hi Adhemerval!

On 3/23/21 18:59, Adhemerval Zanella wrote:
> I am not sure if this is the correct approach, I am seeing it building for powerpc64le with gcc version 10.2.1 20210126:
> 
> | powerpc64le-glibc-linux-gnu-gcc nscd.c -c [...]
> | In file included from ../include/sys/cdefs.h:3,
> |                  from ../include/features.h:484,
> |                  from ../sysdeps/powerpc/bits/floatn.h:22,
> |                  from ../include/stdio.h:7,
> |                  from ../argp/argp.h:23,
> |                  from ../include/argp.h:2,
> |                  from nscd.c:20:
> | ../misc/sys/cdefs.h:503:20: error: ‘__dprintf_chk’ undeclared here (not in a function); did you mean ‘__sprintf_chk’?
> |   503 |   extern __typeof (__##name) __##name \
>       |                    ^~
> | ../libio/bits/stdio-ldbl.h:98:1: note: in expansion of macro ‘__LDBL_REDIR2_DECL’
> |    98 | __LDBL_REDIR2_DECL (dprintf_chk)
> |       | ^~~~~~~~~~~~~~~~~~
> | [...]
> 
> The postprocessor output shows:
> 
> | [...]
> |  2820 extern __typeof (__dprintf_chk) __dprintf_chk __asm ("" "__" "dprintf_chk" "ieee128");
> | [...]
> |  3067 extern int __dprintf_chk (int __fd, int __flag, const char *__restrict __fmt,
> | 3068      ...) __attribute__ ((__format__ (__printf__, 3, 4)));
> 
> Meaning we are not using __typeof *before* the function prototype
> is define.
> 
> I think to proper handle this LLVM limitation we will need to fully
> rework how __LDBL_REDIR2_DECL does the redirect by something similar
> to what __REDIRECT does by defining something like:
> 
> | #if __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 1
> | # ifdef __REDIRECT
> |
> | /* Alias name defined automatically.  */
> | #  define __LDBL_REDIR(name, proto) \
> |  extern name proto __asm__ (__ASMNAME ("__" #name "ieee128"));
> |
> | /* Alias name defined automatically, with leading underscores.  */
> | #  define __LDBL_REDIR2_DECL(name) \
> |    extern __##name proto __asm__ (__ASMNAME ("__" #name "ieee128"));
> 
> |
> | /* Alias name defined manually.  */
> | #  define __LDBL_REDIR1(name, proto, alias) \
> |  extern name proto __asm__ (__ASMNAME (alias));
> 
> And replace __LDBL_REDIR_DECL with __LDBL_REDIR and __LDBL_REDIR1_DECL
> with __LDBL_REDIR1 (while adding the require argument prototype).  It
> will allow to move the stdio-ldbl.h definitions to stdio and remove the
> header.

Do you think you could create a patch for me to test? I think you would be
faster in getting it right. The sparc64 porterbox gcc202 is available for
testing.

The underlying bug [1] is still present in glibc 2.33. I just ran into it
again.

Adrian

> [1] https://sourceware.org/bugzilla/show_bug.cgi?id=27558

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer - glaubitz@debian.org
`. `'   Freie Universitaet Berlin - glaubitz@physik.fu-berlin.de
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