Re: -Wlto-type-mismatch warning in error()

[Gavin Smith]

On Wed, Dec 07, 2022 at 08:57:45PM +0000, Sam James wrote:

> ../gnulib/lib/error.h:33:13: error: type of ‘error’ does not match original 
> declaration [-Werror=lto-type-mismatch]
>    33 | extern void error (int __status, int __errnum, const char *__format, 
> ...)
>       |             ^
> install-info.c:218:1: note: type mismatch in parameter 1
>   218 | error (const char *fmt, ...)
>       | ^
> install-info.c:218:1: note: ‘error’ was previously declared here
> install-info.c:218:1: note: code may be misoptimized unless 
> ‘-fno-strict-aliasing’ is used
> lto1: some warnings being treated as errors
> lto-wrapper: fatal error: //usr/bin/x86_64-pc-linux-gnu-gcc returned 1 exit 
> status
> compilation terminated.
> /usr/lib/gcc/x86_64-pc-linux-gnu/12/../../../../x86_64-pc-linux-gnu/bin/ld: 
> error: lto-wrapper failed
> collect2: error: ld returned 1 exit status
> make[3]: *** [Makefile:1514: ginstall-info] Error 1
> ```
> 
> This is with GCC 12.2.1 20221203.
> 
> We've also seen this in GNU make, so not sure if it's a
> gnulib problem or not, as it may be in lib/error.h (hence CCing bug-gnulib):
> - https://bugs.gentoo.org/863713 (texinfo)
> - https://bugs.gentoo.org/863824 (make)

I expect it is not a gnulib problem.  install-info/install-info.c declares
a function called "error" which appears to clash with a function from glibc.

The function called "error" in install-info is correctly used when
e.g. "install-info one two three" is run, printing

install-info: excess command line argument `three'

It may depend on the configuration process and what parts of gnulib are
being used.  The "error" module is brought in by "xalloc" (which we
ask for explicitly).

>From the Gentoo bug report
> -Werror=lto-type-mismatch:
> User to find possible runtime issues in packages. It likely means the package 
> is unsafe to build & use with LTO.
> For projects using the same identifier but with different types across 
> different files, they must be fixed to be consistent across the codebase.

The simplest way to fix this problem would probably be to rename the "error"
function in install-info.c.  Perhaps this issue has never come up before
because people have not used the LTO options for building.