BUILD: compiler: add a new type modifier __maybe_unused

While gcc only emits warnings about unused static functions, Clang also
emits such a warning when the functions are inlined. This is a bit
annoying at certain places where functions are provided to manipulate
multiple data types and are not yet used. Let's have a type modifier
"__maybe_unused" which sets the "unused" attribute like the Linux kernel
does. It's elegant as it allows the code author to indicate that it knows
that this element might be unused. It works on variables as well, which
is convenient to remove ifdefs around local variables in certain functions,
but doesn't work on labels.

diff --git a/include/common/compiler.h b/include/common/compiler.h
index ee7744c9fd459505dcf56406e70530a89fd3ba87..a13aad5c62f4e9e9280c5fead65f36a79788007a 100644 (file)
--- a/include/common/compiler.h
+++ b/include/common/compiler.h
@@ -77,6 +77,10 @@
 #endif
 #endif
 
+/* silence the "unused" warnings without having to place painful #ifdefs.
+ * For use with variables or functions.
+ */
+#define __maybe_unused __attribute__((unused))
 
 /*
  * Gcc >= 3 provides the ability for the programme to give hints to the