Re: [PATCH 1/2] builtin/merge-file: fix compiler error on MacOS with clang 11.0.0
- From
René Scharfe <l.s.r@web.de>
- Date
- Oct 6, 2022, 21:09 UTC
- Message-ID
- <36cd156b-edb2-062c-9422-bf39aad39a6d@web.de>
- In-Reply-To
- <7cee38788a7a3c2c09a238e01c5bd825445f999d.1665085395.git.gitgitgadget@gmail.com>
Am 06.10.22 um 21:43 schrieb Jeff Hostetler via GitGitGadget:
Show 5 quoted lines
> From: Jeff Hostetler <jeffhost@microsoft.com> > > Add extra set of braces around zero initialization of two array/structure > variables to resolve compiler errors/warnings from clang 11.0.0 on MacOS. > This is not needed on clang 14.0.
Not sure how the Apple version numbers map to LLVM versions. I can reproduce it with Godbolt's Compiler Explorer with clang 8, but not with clang 9 or higher: https://godbolt.org/z/f7f7s9xxz
Funny that type of the "inner" member seems to affect the warning.
Show 17 quoted lines
>
> $ uname -a
> Darwin jeffhost-mbp.local 19.6.0 Darwin Kernel Version 19.6.0: \
> Mon Apr 18 21:50:40 PDT 2022; \
> root:xnu-6153.141.62~1/RELEASE_X86_64 x86_64
> $ clang -v
> Apple clang version 11.0.0 (clang-1100.0.33.17)
> Target: x86_64-apple-darwin19.6.0
> [...]
>
> $ make builtin/merge-file.o
> CC builtin/merge-file.o
> builtin/merge-file.c:29:23: error: suggest braces around initialization \
> of subobject [-Werror,-Wmissing-braces]
> mmfile_t mmfs[3] = { 0 };
> ^
> {}{0} is an idiom to zero-initialize any struct, no matter how deeply nested. It's valid C and the compiler warning about it is not helpful. Shouldn't we rather silence it with -Wno-missing-braces?
On the other hand: Uglifying just three initializations in total isn't that bad. The issue may reappear, though, because most people use compilers that don't issue that spurious warning, I imagine.
Show 29 quoted lines
> builtin/merge-file.c:31:20: error: suggest braces around initialization \
> of subobject [-Werror,-Wmissing-braces]
> xmparam_t xmp = { 0 };
> ^
> {}
> 2 errors generated.
> make: *** [builtin/merge-file.o] Error 1
>
> Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
> ---
> builtin/merge-file.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/builtin/merge-file.c b/builtin/merge-file.c
> index c923bbf2abb..607c3d3f9e1 100644
> --- a/builtin/merge-file.c
> +++ b/builtin/merge-file.c
> @@ -26,9 +26,9 @@ static int label_cb(const struct option *opt, const char *arg, int unset)
> int cmd_merge_file(int argc, const char **argv, const char *prefix)
> {
> const char *names[3] = { 0 };
> - mmfile_t mmfs[3] = { 0 };
> + mmfile_t mmfs[3] = { { 0 } };
> mmbuffer_t result = { 0 };
> - xmparam_t xmp = { 0 };
> + xmparam_t xmp = { { 0 } };
> int ret = 0, i = 0, to_stdout = 0;
> int quiet = 0;
> struct option options[] = {