On Sat, Nov 28, 2020 at 06:44:35AM +0000, Johannes Schindelin via GitGitGadget wrote:

From: Johannes Schindelin <redacted>

0-sized arrays are actually not portable.

Definitely.

 static void test_sizes_to_segments_empty(void)
 {
-	uint64_t sizes[0];
+	uint64_t sizes[1];
 
 	int seglen = 0;
 	struct segment *segs =
-		sizes_to_segments(&seglen, sizes, ARRAY_SIZE(sizes));
+		sizes_to_segments(&seglen, sizes, 0);
 	EXPECT(seglen == 0);
 	reftable_free(segs);

I think passing:

  sizes_to_segments(&seglen, NULL, 0);

may make the code more obvious. Unlike system functions like memcpy(),
we can be assured of whether our functions avoid looking at a
zero-length array (and size_to_segments does follow that rule).

  This function, of course, is nonsense that real code would not do, and
  is just unit-testing sizes_to_segments. I'm not wild in general about
  having a parallel suite of C tests that does not interact with our
  usual tests, but it may be the least bad way to benefit from the
  unit-test coverage that reftable ships with. As a rule, I'd much
  rather see a tool exposing functionality to the command-line, which
  can then be driven independently. I recognize that can end up
  complicated, though.

-Peff