compiler check for unused variables

This is for variables that the compiler itself cannot figure out
(e.g. non-trivial ctors). The classes need to be marked manually.

Change-Id: I0109972e11e20578b1adc32065f701a871ee21aa

1 files changed, 20 insertions, 0 deletions

diff --git a/sal/inc/sal/types.h b/sal/inc/sal/types.h
index f97ecc701438..0baf3d19cb1c 100644
--- a/sal/inc/sal/types.h
+++ b/sal/inc/sal/types.h
@@ -489,6 +489,26 @@ template< typename T1, typename T2 > inline T1 static_int_cast(T2 n) {
 #endif
 #endif
 
+/**
+
+ Annotate classes where a compiler should warn if an instance is unused.
+
+ The compiler cannot warn about unused instances if they have non-trivial
+ or external constructors or destructors. Classes marked with SAL_WARN_UNUSED
+ will be warned about.
+
+ Currently implemented by a Clang compiler plugin.
+
+ @since LibreOffice 3.7
+
+*/
+
+#if defined __clang__
+#define SAL_WARN_UNUSED __attribute__((annotate("lo_warn_unused")))
+#else
+#define SAL_WARN_UNUSED
+#endif
+
 #endif /*_SAL_TYPES_H_ */
 
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