[PATCH 0/13] v2 warning control by group and location (PR 74765)

[Jan-Benedict Glaw]

Hi Martin!

On Fri, 2021-06-04 15:27:04 -0600, Martin Sebor <msebor@gmail.com> wrote:
> This is a revised patch series to add warning control by group and
> location, updated based on feedback on the initial series.
[...]

My automated checking (in this case: Using Debian's "gcc-snapshot"
package) indicates that between versions 1:20210527-1 and
1:20210630-1, building GDB breaks. Your patch is a likely candidate.
It's a case where a method asks for a nonnull argument and later on
checks for NULLness again. The build log is currently available at
(http://wolf.lug-owl.de:8080/jobs/gdb-vax-linux/5), though obviously
breaks for any target:

configure --target=vax-linux --prefix=/tmp/gdb-vax-linux
make all-gdb

[...]
[all 2021-07-16 19:19:25]   CXX    compile/compile.o
[all 2021-07-16 19:19:30] In file included from ./../gdbsupport/common-defs.h:126,
[all 2021-07-16 19:19:30]                  from ./defs.h:28,
[all 2021-07-16 19:19:30]                  from compile/compile.c:20:
[all 2021-07-16 19:19:30] ./../gdbsupport/gdb_unlinker.h: In constructor 'gdb::unlinker::unlinker(const char*)':
[all 2021-07-16 19:19:30] ./../gdbsupport/gdb_assert.h:35:4: error: 'nonnull' argument 'filename' compared to NULL [-Werror=nonnull-compare]
[all 2021-07-16 19:19:30]    35 |   ((void) ((expr) ? 0 :                                                       \
[all 2021-07-16 19:19:30]       |   ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[all 2021-07-16 19:19:30]    36 |            (gdb_assert_fail (#expr, __FILE__, __LINE__, FUNCTION_NAME), 0)))
[all 2021-07-16 19:19:30]       |            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[all 2021-07-16 19:19:30] ./../gdbsupport/gdb_unlinker.h:38:5: note: in expansion of macro 'gdb_assert'
[all 2021-07-16 19:19:30]    38 |     gdb_assert (filename != NULL);
[all 2021-07-16 19:19:30]       |     ^~~~~~~~~~
[all 2021-07-16 19:19:31] cc1plus: all warnings being treated as errors
[all 2021-07-16 19:19:31] make[1]: *** [Makefile:1641: compile/compile.o] Error 1
[all 2021-07-16 19:19:31] make[1]: Leaving directory '/var/lib/laminar/run/gdb-vax-linux/5/binutils-gdb/gdb'
[all 2021-07-16 19:19:31] make: *** [Makefile:11410: all-gdb] Error 2


Code is this:

 31 class unlinker
 32 {
 33  public:
 34 
 35   unlinker (const char *filename) ATTRIBUTE_NONNULL (2)
 36     : m_filename (filename)
 37   {
 38     gdb_assert (filename != NULL);
 39   }

I'm quite undecided whether this is bad behavior of GCC or bad coding
style in Binutils/GDB, or both.

Thanks,
  Jan-Benedict

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