[Bug 1897666] [NEW] FTBFS: nss for groovy ftbfs due to erroneous nonnull check arising from glibc getcwd() annotation

[Alex Murray]

Public bug reported:

As per the archive test rebuild done recently by doko, nss FTBFS due to
a compiler warning raised by gcc-10 (and this fails the build due to the
use of -Werror in CFLAGS):

https://launchpad.net/ubuntu/+archive/test-
rebuild-20200925-groovy/+build/20033437

nsinstall.c: In function ‘main’:
nsinstall.c:70:16: error: argument 1 is null but the corresponding size argument 2 value is 4096 [-Werror=nonnull]
   70 | #define GETCWD getcwd
      |                ^
nsinstall.c:239:8: note: in expansion of macro ‘GETCWD’
  239 |  cwd = GETCWD(0, PATH_MAX);
      |        ^~~~~~
In file included from nsinstall.c:20:
/usr/include/unistd.h:520:14: note: in a call to function ‘getcwd’ declared with attribute ‘write_only (1, 2)’
  520 | extern char *getcwd (char *__buf, size_t __size) __THROW __wur
      |              ^~~~~~
nsinstall.c:70:16: error: argument 1 is null but the corresponding size argument 2 value is 4096 [-Werror=nonnull]
   70 | #define GETCWD getcwd
      |                ^
nsinstall.c:246:13: note: in expansion of macro ‘GETCWD’
  246 |     todir = GETCWD(0, PATH_MAX);
      |             ^~~~~~
In file included from nsinstall.c:20:
/usr/include/unistd.h:520:14: note: in a call to function ‘getcwd’ declared with attribute ‘write_only (1, 2)’
  520 | extern char *getcwd (char *__buf, size_t __size) __THROW __wur
      |              ^~~~~~
cc1: all warnings being treated as errors

According to the upstream bug report at
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96832 this would appear to
be because of the annotation of getcwd() with the access attribute.
However, there seems to be some debate about the best way to resolve
this (whether in glibc or in the callers of getcwd, ie nss) for now I
propose to just disable this check via the use of gcc's #pragma
directive.

** Affects: nss (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: ftbfs patch

** Tags added: ftbfs

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https://bugs.launchpad.net/bugs/1897666

Title:
  FTBFS: nss for groovy ftbfs due to erroneous nonnull check arising
  from glibc getcwd() annotation

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