On Fri, Mar 14, 2025 at 10:40:24AM -0700, Junio C Hamano wrote:

quoted

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Subject: [PATCH] run-command: use errno to check for sigfillset() error

Since enabling -Wunreachable-code, builds with clang on macOS now fail,
complaining that the die_errno() call in:

  if (sigfillset(&all))
	die_errno("sigfillset");

is unreachable. On that platform the manpage documents that sigfillset()
always returns success, and presumably the implementation is a macro or
inline function that does so in a way that is transparent to the
compiler.

Would it work to instead do this here
...

I forgot to say a more important thing.  Between the "let's excempt
developers on macOS" and the "let's see how far we can go with the
warning turned on everywhere and wack-a-mole this particular one
with errno check" patches, I prefer the latter at least for a short
term.

That's my gut feeling, too. I wasn't sure how people would feel about
actually touching the code (whereas the other patches were purely
turning compiler knobs). It may turn into wack-a-mole, but finding out
is part of the experiment.

Your CAN_BE_TAKEN() approach is certainly less subtle, and can be
applied in a more general way. If this is the only spot needed it may be
overkill, but the readability improvement alone probably makes it
worthwhile.

Do you want to turn that into a patch?

-Peff