<string.h>: Define __CORRECT_ISO_CPP_STRING_H_PROTO for Clang [BZ #25232]

Without the asm redirects, strchr et al. are not const-correct.

libc++ has a wrapper header that works with and without
__CORRECT_ISO_CPP_STRING_H_PROTO (using a Clang extension).  But when
Clang is used with libstdc++ or just C headers, the overloaded functions
with the correct types are not declared.

This change does not impact current GCC (with libstdc++ or libc++).

(cherry picked from commit 953ceff17a4a15b10cfdd5edc3c8cae4884c8ec3)

diff --git a/string/string.h b/string/string.h
index 150cfd8b13afef136a1eb2c399587366056b2d81..22cd0fa08fdb12730e70945266699bbd98b3ac5d 100644 (file)
--- a/string/string.h
+++ b/string/string.h
@@ -33,7 +33,8 @@ __BEGIN_DECLS
 #include <stddef.h>
 
 /* Tell the caller that we provide correct C++ prototypes.  */
-#if defined __cplusplus && __GNUC_PREREQ (4, 4)
+#if defined __cplusplus && (__GNUC_PREREQ (4, 4) \
+                           || __glibc_clang_prereq (3, 5))
 # define __CORRECT_ISO_CPP_STRING_H_PROTO
 #endif