X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=src%2Fshared%2Fmacro.h;h=959a9f7fb1533cd11d918ffee7fcc1b8ea22b19f;hb=7ebe131a9f37fe5a3a15f69962d21cb7e063dff8;hp=79bee0396c3a52c4bed07f28f1878915bad8b282;hpb=919ce0b7affc6fbd68598b709faf477f56c22ac1;p=elogind.git

diff --git a/src/shared/macro.h b/src/shared/macro.h
index 79bee0396..959a9f7fb 100644
--- a/src/shared/macro.h
+++ b/src/shared/macro.h
@@ -46,6 +46,14 @@
 #define _alignas_(x) __attribute__((aligned(__alignof(x))))
 #define _cleanup_(x) __attribute__((cleanup(x)))
 
+/* Temporarily disable some warnings */
+#define DISABLE_WARNING_DECLARATION_AFTER_STATEMENT                     \
+        _Pragma("GCC diagnostic push");                                 \
+        _Pragma("GCC diagnostic ignored \"-Wdeclaration-after-statement\"")
+
+#define REENABLE_WARNING                                                \
+        _Pragma("GCC diagnostic pop")
+
 /* automake test harness */
 #define EXIT_TEST_SKIP 77
 
@@ -117,6 +125,13 @@ static inline size_t ALIGN_TO(size_t l, size_t ali) {
                         _a < _b ? _a : _b;      \
                 })
 
+#define LESS_BY(A,B)                            \
+        __extension__ ({                        \
+                        typeof(A) _A = (A);     \
+                        typeof(B) _B = (B);     \
+                        _A > _B ? _A - _B : 0;  \
+                })
+
 #ifndef CLAMP
 #define CLAMP(x, low, high)                                             \
         __extension__ ({                                                \
@@ -147,9 +162,20 @@ static inline size_t ALIGN_TO(size_t l, size_t ali) {
         } while (false)
 
 #if defined(static_assert)
-#define assert_cc(expr) static_assert(expr, #expr)
+/* static_assert() is sometimes defined in a way that trips up
+ * -Wdeclaration-after-statement, hence let's temporarily turn off
+ * this warning around it. */
+#define assert_cc(expr)                                                 \
+        DISABLE_WARNING_DECLARATION_AFTER_STATEMENT;                    \
+        static_assert(expr, #expr);                                     \
+        REENABLE_WARNING
 #else
-#define assert_cc(expr) struct UNIQUE(_assert_struct_) { char x[(expr) ? 0 : -1]; };
+#define assert_cc(expr)                                                 \
+        DISABLE_WARNING_DECLARATION_AFTER_STATEMENT;                    \
+        struct UNIQUE(_assert_struct_) {                                \
+                char x[(expr) ? 0 : -1];                                \
+        };                                                              \
+        REENABLE_WARNING
 #endif
 
 #define assert_return(expr, r)                                          \