[Bug build/31928] New: glibc doesn't compile if the compiler already define _FORTIFY_SOURCE

[Bug build/31928] New: glibc doesn't compile if the compiler already define _FORTIFY_SOURCE

[simon.chopin at canonical dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=31928

            Bug ID: 31928
           Summary: glibc doesn't compile if the compiler already define
                    _FORTIFY_SOURCE
           Product: glibc
           Version: 2.39
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: build
          Assignee: unassigned at sourceware dot org
          Reporter: simon.chopin at canonical dot com
                CC: carlos at redhat dot com
  Target Milestone: ---

In Ubuntu, GCC has been modified to define _FORTIFY_SOURCE in the preprocessor
driver, resulting in failures to build glibc, with the following error (with
--disable-werror):

syslog.c: In function ‘__vsyslog_internal’:
syslog.c:95:30: error: inlining failed in call to ‘always_inline’ ‘syslog’:
function not inlinable
   95 | ldbl_strong_alias (__syslog, syslog)

We're shipping a patch to adress this in 2.39, I still need to rebase it and
clean it up:

https://git.launchpad.net/~ubuntu-core-dev/ubuntu/+source/glibc/tree/debian/patches/ubuntu/fix-fortify-source.patch

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[Bug build/31928] glibc doesn't compile if the compiler already define _FORTIFY_SOURCE

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=31928

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fweimer at redhat dot com

--- Comment #1 from Florian Weimer <fweimer at redhat dot com> ---
You could add a flag _DISTRO_EVADE_FORTIFY_SOURCE, similar to bug 31624. Then
no glibc patching will be required.

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[Bug build/31928] glibc doesn't compile if the compiler already define _FORTIFY_SOURCE

[sam at gentoo dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31928

Sam James <sam at gentoo dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |sam at gentoo dot org
           See Also|                            |https://sourceware.org/bugz
                   |                            |illa/show_bug.cgi?id=31624

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[Bug build/31928] glibc doesn't compile if the compiler already define _FORTIFY_SOURCE

[simon.chopin at canonical dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=31928

--- Comment #2 from Simon Chopin <simon.chopin at canonical dot com> ---
Or we could *not* use -Wp,-U_FORTIFY_SOURCE ? I couldn't find any rationale for
it in the first place.

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[Bug build/31928] glibc doesn't compile if the compiler already define _FORTIFY_SOURCE

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=31928

--- Comment #3 from Florian Weimer <fweimer at redhat dot com> ---
(In reply to Simon Chopin from comment #2)
> Or we could *not* use -Wp,-U_FORTIFY_SOURCE ? I couldn't find any rationale
> for it in the first place.

It's needed to avoid duplicate function bodies. See:

[PATCH 00/11] Build getdomainname, gethostname, syslog with fortification
<https://inbox.sourceware.org/libc-alpha/cover.1707491940.git.fweimer@redhat.com/>

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[Bug build/31928] glibc doesn't compile if the compiler already define _FORTIFY_SOURCE

[adhemerval.zanella at linaro dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31928

Adhemerval Zanella <adhemerval.zanella at linaro dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |adhemerval.zanella at linaro dot o
                   |                            |rg

--- Comment #4 from Adhemerval Zanella <adhemerval.zanella at linaro dot org> ---
(In reply to Florian Weimer from comment #3)
> (In reply to Simon Chopin from comment #2)
> > Or we could *not* use -Wp,-U_FORTIFY_SOURCE ? I couldn't find any rationale
> > for it in the first place.
> 
> It's needed to avoid duplicate function bodies. See:
> 
> [PATCH 00/11] Build getdomainname, gethostname, syslog with fortification
> <https://inbox.sourceware.org/libc-alpha/cover.1707491940.git.fweimer@redhat.
> com/>

Why do we need to use -Wp instead of just -U? It seems that -Wp does not play
nice if compiler defaults to define _FORTIFY_SOURCE.

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[Bug build/31928] glibc doesn't compile if the compiler already define _FORTIFY_SOURCE

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=31928

--- Comment #5 from Florian Weimer <fweimer at redhat dot com> ---
If -U works, we can switch to that. The use of -Wp goes back to CFLAGS settings
which needed to be compatible with GCJ, where -D had a different meaning.
Hence, -Wp,-D_FORTIFY_SOURCE=2 came into being, and it has been carried forward
ever since.

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