assert: Suppress pedantic warning caused by statement expression

diff --git a/ChangeLog b/ChangeLog
index 3a795ecfa77e92fd1efffcd09470d356af926c6d..000dc6d47b95c88558beab7b6460bb76693ef17d 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2017-08-11  Florian Weimer  <fweimer@redhat.com>
+
+       [BZ #21242]
+       * assert/assert.h [__GNUC__ && !__STRICT_ANSI__] (assert):
+       Suppress pedantic warning resulting from statement expression.
+       (__ASSERT_FUNCTION): Add missing __extension__.
+
 2017-08-11  Siddhesh Poyarekar  <siddhesh@sourceware.org>
 
        * benchtests/bench-memmove-large.c: Print output in JSON

diff --git a/assert/assert.h b/assert/assert.h
index 22f019537cea4d15fa4e915eb7989d7bf4bc3d2f..6801cfeb10debf7a9e0d6e425ecfb0c68b2ca42a 100644 (file)
--- a/assert/assert.h
+++ b/assert/assert.h
@@ -91,13 +91,19 @@ __END_DECLS
      ? __ASSERT_VOID_CAST (0)                                          \
      : __assert_fail (#expr, __FILE__, __LINE__, __ASSERT_FUNCTION))
 # else
+/* The first occurrence of EXPR is not evaluated due to the sizeof,
+   but will trigger any pedantic warnings masked by the __extension__
+   for the second occurrence.  The explicit comparison against zero is
+   required to support function pointers and bit fields in this
+   context, and to suppress the evaluation of variable length
+   arrays.  */
 #  define assert(expr)                                                 \
-    ({                                                                 \
+  ((void) sizeof ((expr) == 0), __extension__ ({                       \
       if (expr)                                                                \
         ; /* empty */                                                  \
       else                                                             \
         __assert_fail (#expr, __FILE__, __LINE__, __ASSERT_FUNCTION);  \
-    })
+    }))
 # endif
 
 # ifdef        __USE_GNU
@@ -113,7 +119,7 @@ __END_DECLS
    C9x has a similar variable called __func__, but prefer the GCC one since
    it demangles C++ function names.  */
 # if defined __cplusplus ? __GNUC_PREREQ (2, 6) : __GNUC_PREREQ (2, 4)
-#   define __ASSERT_FUNCTION   __PRETTY_FUNCTION__
+#   define __ASSERT_FUNCTION   __extension__ __PRETTY_FUNCTION__
 # else
 #  if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
 #   define __ASSERT_FUNCTION   __func__