Re: [RFA] Fix the clang build

[Simon Marchi <simon.marchi@polymtl.ca>]

On 2018-05-10 10:40, Tom Tromey wrote:
> Simon pointed out that gdb would not build with clang, due to the
> addition of -Wimplicit-fallthrough.  This patch fixes the problem by
> using -Wimplicit-fallthrough=3 -- this does not work with clang,
> bypassing the issue.
> 
> Tested by rebuilding with both gcc and clang; and also by verifying
> that -Wimplicit-fallthrough=3 is used in the gcc build.
> 
> I will file a follow-up bug to convert the fall-through comments to a
> form that can be used by both clang and gcc.

Thanks, that patch is fine with me.

To be clear for those who might not be aware of the mechanism: the 
configure script tests each warning flag to see if it's supported by the 
current compiler.  Since -Wimplicit-fallthrough=3 is not supported by 
clang, it won't be included.  This means that we won't get the 
fallthrough warnings when building with clang.  I think it's fine, since 
we get them through gcc, so an unintended fallthrough would be found 
pretty quickly anyway.

Simon