assert: Suppress pedantic warning caused by statement expression [BZ #21242]

(cherry picked from commit 8b2c63e4e2ad1fd161f80004ed30624f2a37b57b)

diff --git a/ChangeLog b/ChangeLog
index 5ea9b8baa76a6df156b1eb76db5931d4015614bf..0057c0902a2aec293474b2080c7471181f563146 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__.
+
 2017-08-10  Florian Weimer  <fweimer@redhat.com>
 
        * malloc/malloc.c (get_max_fast): Reimplement as an inline

diff --git a/NEWS b/NEWS
index ec6cf341226c6e940ad85a871d810041105575c4..d57c4052cf1775f598b01de2372dc372d7236173 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -9,6 +9,7 @@ Version 2.26.1
 
 The following bugs are resolved with this release:
 
+  [21242] assert: Suppress pedantic warning caused by statement expression
   [21885] getaddrinfo: Release resolver context on error in gethosts
   [21932] Unpaired __resolv_context_get in generic get*_r implementation
 \f

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__