linux-kernel - [patch] compiler, clang: suppress warning for unused static inline functions

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Message-ID: <alpine.DEB.2.10.1705241400510.49680@chino.kir.corp.google.com>
Date:   Wed, 24 May 2017 14:01:15 -0700 (PDT)
From:   David Rientjes <rientjes@...gle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
cc:     Matthias Kaehlcke <mka@...omium.org>,
        Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        Joonsoo Kim <iamjoonsoo.kim@....com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Douglas Anderson <dianders@...omium.org>
Subject: [patch] compiler, clang: suppress warning for unused static inline
 functions

GCC explicitly does not warn for unused static inline functions for
-Wunused-function.  The manual states:

	Warn whenever a static function is declared but not defined or
	a non-inline static function is unused.

Clang does warn for static inline functions that are unused.

It turns out that suppressing the warnings avoids potentially complex
#ifdef directives, which also reduces LOC.

Supress the warning for clang.

Signed-off-by: David Rientjes <rientjes@...gle.com>
---
 include/linux/compiler-clang.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
--- a/include/linux/compiler-clang.h
+++ b/include/linux/compiler-clang.h
@@ -15,3 +15,10 @@
  * with any version that can compile the kernel
  */
 #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
+
+/*
+ * GCC does not warn about unused static inline functions for
+ * -Wunused-function.  This turns out to avoid the need for complex #ifdef
+ * directives.  Suppress the warning in clang as well.
+ */
+#define inline inline __attribute__((unused))