Re: Linux 4.19 and GCC 9

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Jun 10, 2019 at 12:14:07PM -0300, Arnaldo Carvalho de Melo wrote:
> Em Mon, Jun 10, 2019 at 12:21:51AM -0700, Ivan Babrou escreveu:
> > Looks like 4.19.49 received some patches for GCC 9+, but unfortunately
> > perf still doesn't want to compile:
> > 
> > [07:15:32]In file included from /usr/include/string.h:635,
> > [07:15:32] from util/debug.h:7,
> > [07:15:32] from builtin-help.c:15:
> > [07:15:32]In function 'strncpy',
> > [07:15:32] inlined from 'add_man_viewer' at builtin-help.c:192:2,
> > [07:15:32] inlined from 'perf_help_config' at builtin-help.c:284:3:
> > [07:15:32]/usr/include/x86_64-linux-gnu/bits/string3.h:126:10: error:
> > '__builtin_strncpy' output truncated before terminating nul copying as
> > many bytes from a string as its length [-Werror=stringop-truncation]
> > [07:15:32] 126 | return __builtin___strncpy_chk (__dest, __src, __len,
> > __bos (__dest));
> > [07:15:32] | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > [07:15:32]builtin-help.c: In function 'perf_help_config':
> > [07:15:32]builtin-help.c:187:15: note: length computed here
> > [07:15:32] 187 | size_t len = strlen(name);
> > [07:15:32] | ^~~~~~~~~~~~
> > [07:15:32]cc1: all warnings being treated as errors
> 
> The patch below should've taken care of that, and it has a Fixes: tag,
> i.e. the stable scripts should've noticed that, and it was noticed with
> gcc 8.2.

No, stable scripts do not always pick up the "Fixes:" tag, they are only
guaranteed to pick up the "cc: stable@" tag.  Sometimes we catch the
fixes ones too, but not always by far.

Anyway, I'll queue this patch up after this next round of kernels are
released, thanks!

greg k-h