Re: master 6e2e7265a04: Prefer static switch-case checking in pdumper

[Stefan Kangas]

Pip Cet <pipcet@protonmail.com> writes:

> "Stefan Kangas" <stefankangas@gmail.com> writes:
>
>> branch: master
>> commit 6e2e7265a04f63f482db7fbdfd8e2519d8bfe03e
>> Author: Stefan Kangas <stefankangas@gmail.com>
>> Commit: Stefan Kangas <stefankangas@gmail.com>
>>
>>     Prefer static switch-case checking in pdumper
>
> This change causes many compiler warnings (current gcc, CFLAGS=-O2):
>
> pdumper.c:4726:15: warning: ‘mem_flags’ may be used uninitialized 
> [-Wmaybe-uninitialized]
>  4726 |     mem_flags |= MAP_FIXED;
>       |               ^
>
> Such warnings will not usually appear in -O0 builds.
>
> I'm also not sure that this is what is meant by static checking.  As
> discussed before, GCC will not assume that the switch value is in the
> enum just because of its type, and treats the fall-through code as
> reachable if it doesn't abort.

I tested this with Clang, which doesn't seem to have a problem.

I'm not sure what is the best fix.  Maybe a redundant initialization is
better than reverting the relevant chunks (and losing -Wswitch warnings
again)?  Or should we re-add the fallthrough to make GCC happy?