Re: Add "-Wimplicit-fallthrough" to default flags (was Re: pgsql: Support FETCH FIRST WITH TIES)

On 2020-May-12, Alvaro Herrera wrote:

> I get no warnings with this (gcc 8), but ccache seems to save warnings
> in one run so that they can be thrown in a later one.  I'm not sure what
> to make of that, but ccache -d proved that beyond reasonable doubt and
> ccache -clear got rid of the lot.

Fixed one straggler in contrib, and while testing it I realized why
ccache doesn't pay attention to the changes I was doing in the file:
ccache compares the *preprocessed* version of the file and only if that
differs from the version that was cached last, ccache sends the new one
to the compiler; and of course these comments are not present in the
preprocessed version, so changing only the comment accomplishes nothing.
You have to touch one byte outside of any comments.

I bet this is going to bite someone ... maybe we'd be better off going
all the way to -Wimplicit-fallthrough=5 and use the
__attribute__((fallthrough)) stuff instead.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
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