Re: [platform-testers] texinfo-6.6.90 pretest

[Eli Zaretskii]

> From: Bruno Haible <address@hidden>
> Cc: address@hidden, address@hidden, address@hidden
> Date: Tue, 20 Aug 2019 23:09:05 +0200
> 
> > > >      install-info.c: In function 'split_entry':
> > > >      install-info.c:1624:17: warning: 'strncat' specified bound 2 
> > > > equals source length [-Wstringop-overflow=]
> > > >                       strncat (*description, "  ", 2);
> > > >                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > > > 
> > > 
> > > The warnings are clearly pointless, because the amount of memory
> > > allocated for *description is unknown to the compiler.
> > > 
> > > Which GCC options did you specify?
> > 
> > I didn't specify any options, the options in effect were those that
> > the Texinfo build system specifies.
> 
> Strange. On a glibc system, I get different results:
> 
> * With gcc 8.3.0, no warnings in install-info.c.
> 
> * With gcc 9.2.0, just one warning:
> 
> In file included from /usr/include/string.h:630,
>                  from ../gnulib/lib/string.h:41,
>                  from ../../system.h:34,
>                  from ../../install-info/install-info.c:18:
> ../../install-info/install-info.c: In function 'split_entry.constprop':
> ../../install-info/install-info.c:1634:11: warning: '__builtin_strncat' 
> output truncated before terminating nul copying as many bytes from a string 
> as its length [-Wstringop-truncation]
>  1634 |           strncat (*description, ptr, length);
>       |           ^~~~~~~
> ../../install-info/install-info.c:1633:27: note: length computed here
>  1633 |           size_t length = strlen (ptr);
>       |                           ^~~~~~~~~~~~

My GCC version is 8.2.0.

Also, did your compilation use -O2 (that should be the default,
AFAIU)?  I think these warnings mostly require the optimization pass
to be emitted.

One other thought is to disable builtin strncat, and see if that
matters.