From: Jeff Hostetler <git@jeffhostetler.com>
Date: Fri, 07 Oct 2022 20:56:01 GMT
Subject: Re: [PATCH 0/2] Fix syntax errors under clang 11.0.0 on MacOS
Message-ID: <58d3ef47-2196-4f59-692a-fc86dfbc1252@jeffhostetler.com>
In-Reply-To: <ec920650-4334-a6f2-6d6f-241899dd79ec@web.de>



On 10/7/22 4:28 PM, René Scharfe wrote:
> Am 07.10.22 um 19:49 schrieb Junio C Hamano:
>>
>> My preference is to flip the -Wno-missing-braces bit in
>> config.mak.uname only for folks who use the version of clang on
>> macOS when that clang claims to be clang11 (my understanding of
>> René's experiment[*] is that versions of (real) clang 9 or newer
>> perfectly well understand that {0} is an accpetable way to specify
>> zero initialization for any structure, with possible nesting).
>>
>> [Reference]
>>
>> * https://lore.kernel.org/git/36cd156b-edb2-062c-9422-bf39aad39a6d@web.de/
> 
> Wikipedia has a map that says Apple calls the LLVM clang 8 (i.e. the
> real one) "11.0.0" and clang 9 "11.0.3":
> 
> https://en.wikipedia.org/wiki/Xcode#Xcode_11.0_-_14.x_(since_SwiftUI_framework)_2
> 
> Perhaps like this?  (No sign-off because I'm not comfortable with that
> make function syntax, but feel free to steal salvageable parts.)
> 
> diff --git a/config.mak.dev b/config.mak.dev
> index 4fa19d361b..4d59c9044f 100644
> --- a/config.mak.dev
> +++ b/config.mak.dev
> @@ -69,6 +69,14 @@ DEVELOPER_CFLAGS += -Wno-missing-braces
>   endif
>   endif
> 
> +# LLVM clang older than 9 and Apple clang older than 12 complain
> +# about initializing a struct-within-a-struct using just "{ 0 }"
> +ifneq ($(filter clang1,$(COMPILER_FEATURES)),)
> +ifeq ($(filter $(if $(filter Darwin,$(uname_S)),clang12,clang9),$(COMPILER_FEATURES)),)
> +DEVELOPER_CFLAGS += -Wno-missing-braces
> +endif
> +endif
> +

So if I understand you correctly, Apple clang 11 is broken
and Apple clang 12 is good.

I was getting ready to send (as soon as the CI finished)
the following a simple to add the -Wno... for clang 11 and
below on Darwin.

+ifeq ($(uname_S),Darwin)
+# Older versions of Apple clang complain about initializing a
+# struct-within-a-struct using just "{0}" rather than "{{0}}".
+# More recent versions do not.  This error is considered a
+# false-positive and not worth fixing, so just disable it.
+ifeq ($(filter clang12,$(COMPILER_FEATURES)),)
+DEVELOPER_CFLAGS += -Wno-missing-braces
+endif
+endif

I'm not sure I understand all of what your suggestion does.

Jeff