On Wed, Nov 25, 2020 at 1:33 PM Finn Thain [off-list ref] wrote:

Or do you think that a codebase can somehow satisfy multiple checkers and
their divergent interpretations of the language spec?

Have we found any cases yet that are divergent? I don't think so.  It
sounds to me like GCC's cases it warns for is a subset of Clang's.
Having additional coverage with Clang then should ensure coverage for
both.

quoted

This is not a shiny new warning; it's already on for GCC and has existed
in both compilers for multiple releases.

Perhaps you're referring to the compiler feature that lead to the
ill-fated, tree-wide /* fallthrough */ patch series.

When the ink dries on the C23 language spec and the implementations figure
out how to interpret it then sure, enforce the warning for new code -- the
cost/benefit analysis is straight forward. However, the case for patching
existing mature code is another story.

I don't think we need to wait for the ink to dry on the C23 language
spec to understand that implicit fallthrough is an obvious defect of
the C language.  While the kernel is a mature codebase, it's not
immune to bugs.  And its maturity has yet to slow its rapid pace of
development.
-- 
Thanks,
~Nick Desaulniers