Re: [PATCH] gdbsupport: better detection of -Wmissing-prototypes support

[Pedro Alves <pedro@palves.net>]

On 2021-09-24 2:40 p.m., Simon Marchi via Gdb-patches wrote:
> On 2021-09-24 9:16 a.m., Andrew Burgess wrote:
>> It has been pointed out to me on IRC (thanks Simon), that this issue
>> is not GCC, but ccache:
>>
>>   https://github.com/ccache/ccache/issues/738#issuecomment-740133374
>>
>> So this patch certainly shouldn't go in as it is currently written.
>>
>> It's still pretty annoying seeing those warnings though, so I wonder
>> if we can consider having a work around for this ccache issue in the
>> GDB configure scripts?
>>
>> Maybe something as simple as setting CCACHE_DISABLE in the environment
>> prior to running the AM_GDB_WARNINGS checks?
>>
>> All ideas welcome...
> 
> Either way would be fine with me:
> 
>  - to use AC_LINK_IFELSE all the time (I don't think the execution time
>    would be significantly higher)
>  - to set CCACHE_DISABLE during the execution of AM_GDB_WARNINGS

Does working around this in configure tests still mean that when using ccache
for really building gdb, ccache will still misreorder arguments and thus
potentially a -Wmissing-prototypes warning would not be turned into an error?

So, here's another option, I think:

#3 - drop -Wmissing-prototypes completely.

As the GCC warning says,

  cc1plus: warning: command line option ‘-Wmissing-prototypes’ is valid for C/ObjC but not for C++

it's only valid for C, not C++.  Do we compile anything with a C compiler nowadays?