Re: [PATCH] GDB: Fix detection of ELF support when configuring with -Werror

[Alexander Richardson via Gdb-patches <gdb-patches@sourceware.org>]

On Wed, 11 Nov 2020 at 20:48, Simon Marchi <simark@simark.ca> wrote:
>
> On 2020-11-11 4:20 a.m., Alex Richardson via Gdb-patches wrote:
> > I was getting "I'm sorry, Dave, I can't do that.  Symbol format `elf64-littleriscv' unknown."
> > errors after updating from GDB 8.3 to 10. Bisecting showed that since
> > commit 1ff6de031241c59d0ff9fa01d3c0a4049b0e97c9, bfd.h depends on strncmp()
> > being present, so configuring with -Werror results in the check for ELF
> > support in BFD failing:
> > .../gdb/gdb/../bfd/elf-bfd.h: In function 'bfd_section_is_ctf':
> > .../gdb/gdb/../bfd/elf-bfd.h:3086:10: error: implicit declaration of function 'strncmp' [-Werror=implicit-function-declaration]
> >    return strncmp (name, ".ctf", 4) == 0 && (name[4] == 0 || name[4] == '.');
> > ---
> >  gdb/acinclude.m4 | 1 +
> >  gdb/configure    | 2 ++
> >  2 files changed, 3 insertions(+)
> >
> > diff --git a/gdb/acinclude.m4 b/gdb/acinclude.m4
> > index 64574e26314..68520d6d938 100644
> > --- a/gdb/acinclude.m4
> > +++ b/gdb/acinclude.m4
> > @@ -266,6 +266,7 @@ AC_DEFUN([GDB_AC_CHECK_BFD], [
> >      [AC_LINK_IFELSE(
> >         [AC_LANG_PROGRAM(
> >         [#include <stdlib.h>
> > +        #include <string.h>
> >          #include "bfd.h"
> >          #include "$4"],
> >         [return $3;]
> > diff --git a/gdb/configure b/gdb/configure
> > index 4a03cd9c3ec..ddbeefe426e 100755
> > --- a/gdb/configure
> > +++ b/gdb/configure
> > @@ -16745,6 +16745,7 @@ else
> >    cat confdefs.h - <<_ACEOF >conftest.$ac_ext
> >  /* end confdefs.h.  */
> >  #include <stdlib.h>
> > +        #include <string.h>
> >          #include "bfd.h"
> >          #include "elf-bfd.h"
> >  int
> > @@ -16858,6 +16859,7 @@ else
> >    cat confdefs.h - <<_ACEOF >conftest.$ac_ext
> >  /* end confdefs.h.  */
> >  #include <stdlib.h>
> > +        #include <string.h>
> >          #include "bfd.h"
> >          #include "mach-o.h"
> >  int
> > --
> > 2.29.1
> >
>
> Since elf-bfd.h uses strncmp, I think it should include string.h.  Is there a good reason not to do that?
>

Hi Simon,

that's what I originally planned, but it seems like elf-bfd.h (and the
headers it includes) don't include any system headers. Since I'm not
familiar with any of this code I assumed this was intentional.

Alex