Re: [PATCH 0/2] Fix syntax errors under clang 11.0.0 on MacOS

From: René Scharfe <l.s.r@web.de>
Date: Oct 7, 2022, 20:28 UTC
Message-ID: <ec920650-4334-a6f2-6d6f-241899dd79ec@web.de>
In-Reply-To: <xmqqpmf3frr5.fsf@gitster.g>

Am 07.10.22 um 19:49 schrieb Junio C Hamano:

Show 11 quoted lines

>
> 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),$(COMPILER_FEATURES)),)
+DEVELOPER_CFLAGS += -Wno-missing-braces
+endif
+endif
+
 # https://bugzilla.redhat.com/show_bug.cgi?id=2075786
 ifneq ($(filter gcc12,$(COMPILER_FEATURES)),)
 DEVELOPER_CFLAGS += -Wno-error=stringop-overread