Re: [PATCH] range-diff: fix some 'hdr-check' and sparse warnings

[Jeff King <peff@peff.net>]

On Wed, Jul 17, 2019 at 11:13:04AM -0700, Junio C Hamano wrote:

> Jeff King <peff@peff.net> writes:
> 
> > ... My big question is if we use "{}" for gcc (and
> > compatible friends), does that squelch all of the complaints from other
> > compilers and tools that might see the "{0}" version? In particular,
> > does it work for sparse?
> 
> Yeah, I agree that it is the most important question.  The best
> solution is not to do the macro, use "= { 0 };" everywhere *and*
> somehow arrange sparse not to complain about it.  I am not sure if
> the last part is doable, though.

I did just check "make range-diff.sp" with this diff:

diff --git a/range-diff.c b/range-diff.c
index ba1e9a4265..481cefff3e 100644
--- a/range-diff.c
+++ b/range-diff.c
@@ -102,7 +102,7 @@ static int read_patches(const char *range, struct string_list *list)
 		}
 
 		if (starts_with(line, "diff --git")) {
-			struct patch patch = { 0 };
+			struct patch patch = { };
 			struct strbuf root = STRBUF_INIT;
 			int linenr = 0;
 

and it seems OK. So presumably we could just lump sparse into the list
of gcc-compatible platforms, and it would work. But it does require the
macro still for other hosts.

Other than that, our options seem to be:

  1. Live with it. IIRC we're already not sparse-clean, and Ramsay
     mostly looks at the diff to find new problems.

  2. Pass -Wno-non-pointer-null to sparse. Unfortunately that also
     disables more useful warnings (like passing "0" instead of NULL to
     a function).

  3. Switch to NULL here, and adhere to that going forward.

-Peff