From: Jan Janssen <medhefgo@web.de>
Date: Sat, 28 May 2022 09:41:10 +0000 (+0200)
Subject: meson: Document why -Wimplicit-fallthrough is not used with clang
X-Git-Tag: v252-rc1~909^2
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=c0f5d58c9ab77fd9a12ba83ee0171d836b66d0b1;p=thirdparty%2Fsystemd.git

meson: Document why -Wimplicit-fallthrough is not used with clang

This changes the macro to ensure proper fallthrough attributes are
used with clang in case this option is added in the future.
---

diff --git a/meson.build b/meson.build
index f416b4f234b..38ebe509f64 100644
--- a/meson.build
+++ b/meson.build
@@ -351,6 +351,9 @@ possible_common_cc_flags = [
         '-Werror=shift-overflow=2',
         '-Werror=undef',
         '-Wfloat-equal',
+        # gperf prevents us from enabling this because it does not emit fallthrough
+        # attribute with clang.
+        #'-Wimplicit-fallthrough',
         '-Wimplicit-fallthrough=5',
         '-Winit-self',
         '-Wlogical-op',
diff --git a/src/fundamental/macro-fundamental.h b/src/fundamental/macro-fundamental.h
index eb43cf3647c..59d63e8e5da 100644
--- a/src/fundamental/macro-fundamental.h
+++ b/src/fundamental/macro-fundamental.h
@@ -40,7 +40,7 @@
 #  define _alloc_(...) __attribute__((__alloc_size__(__VA_ARGS__)))
 #endif
 
-#if __GNUC__ >= 7
+#if __GNUC__ >= 7 || __clang__
 #  define _fallthrough_ __attribute__((__fallthrough__))
 #else
 #  define _fallthrough_