Check for alloc_size attribute in configure.ac

Macros.h

@@ -37,8 +37,6 @@
 #define ATTR_NONNULL                    __attribute__((nonnull))
 #define ATTR_NORETURN                   __attribute__((noreturn))
 #define ATTR_UNUSED                     __attribute__((unused))
-#define ATTR_ALLOC_SIZE1(a)             __attribute__((alloc_size (a)))
-#define ATTR_ALLOC_SIZE2(a, b)          __attribute__((alloc_size (a, b)))
 #define ATTR_MALLOC                     __attribute__((malloc))
 
 #else /* __GNUC__ */
@@ -47,12 +45,22 @@
 #define ATTR_NONNULL
 #define ATTR_NORETURN
 #define ATTR_UNUSED
-#define ATTR_ALLOC_SIZE1(a)
-#define ATTR_ALLOC_SIZE2(a, b)
 #define ATTR_MALLOC
 
 #endif /* __GNUC__ */
 
+#ifdef HAVE_ATTR_ALLOC_SIZE
+
+#define ATTR_ALLOC_SIZE1(a)             __attribute__((alloc_size (a)))
+#define ATTR_ALLOC_SIZE2(a, b)          __attribute__((alloc_size (a, b)))
+
+#else
+
+#define ATTR_ALLOC_SIZE1(a)
+#define ATTR_ALLOC_SIZE2(a, b)
+
+#endif /* HAVE_ATTR_ALLOC_SIZE */
+
 // ignore casts discarding const specifier, e.g.
 //     const char []     ->  char * / void *
 //     const char *[2]'  ->  char *const *

configure.ac

@@ -173,6 +173,20 @@ AC_TYPE_UINT16_T
 AC_TYPE_UINT32_T
 AC_TYPE_UINT64_T
 
+AC_MSG_CHECKING(for alloc_size)
+old_CFLAGS="$CFLAGS"
+CFLAGS="$CFLAGS -Wno-error -Werror=attributes"
+AC_COMPILE_IFELSE([
+   AC_LANG_SOURCE(
+      [
+         __attribute__((alloc_size(1))) char* my_alloc(int size) { return 0; }
+      ],[]
+   )],
+   AC_DEFINE([HAVE_ATTR_ALLOC_SIZE], 1, [The alloc_size attribute is supported.])
+   AC_MSG_RESULT(yes),
+   AC_MSG_RESULT(no))
+CFLAGS="$old_CFLAGS"
+
 # ----------------------------------------------------------------------