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* [PATCH kbuild] Makefile.extrawarn: disable -Woverride-init in W=1
@ 2021-04-07  0:24 Marek Behún
  2021-04-07  7:14 ` Arnd Bergmann
  0 siblings, 1 reply; 4+ messages in thread
From: Marek Behún @ 2021-04-07  0:24 UTC (permalink / raw)
  To: linux-kbuild
  Cc: Marek Behún, Arnd Bergmann, Nathan Chancellor,
	Masahiro Yamada, Andrew Lunn, netdev

The -Wextra flag enables -Woverride-init in newer versions of GCC.

This causes the compiler to warn when a value is written twice in a
designated initializer, for example:
  int x[1] = {
    [0] = 3,
    [0] = 3,
  };

Note that for clang, this was disabled from the beginning with
-Wno-initializer-overrides in commit a1494304346a3 ("kbuild: add all
Clang-specific flags unconditionally").

This prevents us from implementing complex macros for compile-time
initializers.

For example a macro of the form INITIALIZE_BITMAP(bits...) that can be
used as
  static DECLARE_BITMAP(bm, 64) = INITIALIZE_BITMAP(0, 1, 32, 33);
can only be implemented by allowing a designated initializer to
initialize the same members multiple times (because the compiler
complains even if the multiple initializations initialize to the same
value).

Disable the -Woverride-init flag.

Signed-off-by: Marek Behún <kabel@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Nathan Chancellor <natechancellor@gmail.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: netdev@vger.kernel.org
---
 scripts/Makefile.extrawarn | 1 +
 1 file changed, 1 insertion(+)

diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
index d53825503874..cf7bc1eec5e3 100644
--- a/scripts/Makefile.extrawarn
+++ b/scripts/Makefile.extrawarn
@@ -36,6 +36,7 @@ KBUILD_CFLAGS += $(call cc-option, -Wstringop-truncation)
 KBUILD_CFLAGS += -Wno-missing-field-initializers
 KBUILD_CFLAGS += -Wno-sign-compare
 KBUILD_CFLAGS += -Wno-type-limits
+KBUILD_CFLAGS += $(call cc-disable-warning, override-init)
 
 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN1
 
-- 
2.26.2


^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2021-04-07 20:44 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2021-04-07  0:24 [PATCH kbuild] Makefile.extrawarn: disable -Woverride-init in W=1 Marek Behún
2021-04-07  7:14 ` Arnd Bergmann
2021-04-07 14:49   ` Marek Behún
2021-04-07 20:44   ` Marek Behún

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