1 files changed, 23 insertions, 18 deletions
diff --git a/include/cstring b/include/cstring
index d60b9923c..5e1837202 100644
--- a/include/cstring
+++ b/include/cstring
@@ -78,37 +78,42 @@ using ::strcmp;
 using ::strncmp;
 using ::strcoll;
 using ::strxfrm;
+using ::strcspn;
+using ::strspn;
+#ifndef _LIBCPP_HAS_NO_THREAD_UNSAFE_C_FUNCTIONS
+using ::strtok;
+#endif
+using ::memset;
+using ::strerror;
+using ::strlen;
 
-using ::memchr;
+// MSVCRT, GNU libc and its derivates already have the correct prototype in
+// <string.h> if __cplusplus is defined. This macro can be defined by users if
+// their C library provides the right signature.
+#if defined(__GLIBC__) || defined(_LIBCPP_MSVCRT) || defined(__sun__) || \
+    defined(_STRING_H_CPLUSPLUS_98_CONFORMANCE_)
+#define _LIBCPP_STRING_H_HAS_CONST_OVERLOADS
+#endif
 
+#ifdef _LIBCPP_STRING_H_HAS_CONST_OVERLOADS
 using ::strchr;
-
-using ::strcspn;
-
 using ::strpbrk;
-
 using ::strrchr;
-
-using ::strspn;
-
+using ::memchr;
 using ::strstr;
-
-// MSVCRT, GNU libc and its derivates already have the correct prototype in <string.h> #ifdef __cplusplus
-#if !defined(__GLIBC__) && !defined(_LIBCPP_MSVCRT) && !defined(__sun__) && !defined(_STRING_H_CPLUSPLUS_98_CONFORMANCE_)
+#else
+inline _LIBCPP_INLINE_VISIBILITY const char* strchr(const char* __s, int __c) {return ::strchr(__s, __c);}
 inline _LIBCPP_INLINE_VISIBILITY       char* strchr(      char* __s, int __c) {return ::strchr(__s, __c);}
+inline _LIBCPP_INLINE_VISIBILITY const char* strpbrk(const char* __s1, const char* __s2) {return ::strpbrk(__s1, __s2);}
 inline _LIBCPP_INLINE_VISIBILITY       char* strpbrk(      char* __s1, const char* __s2) {return ::strpbrk(__s1, __s2);}
+inline _LIBCPP_INLINE_VISIBILITY const char* strrchr(const char* __s, int __c) {return ::strrchr(__s, __c);}
 inline _LIBCPP_INLINE_VISIBILITY       char* strrchr(      char* __s, int __c) {return ::strrchr(__s, __c);}
+inline _LIBCPP_INLINE_VISIBILITY const void* memchr(const void* __s, int __c, size_t __n) {return ::memchr(__s, __c, __n);}
 inline _LIBCPP_INLINE_VISIBILITY       void* memchr(      void* __s, int __c, size_t __n) {return ::memchr(__s, __c, __n);}
+inline _LIBCPP_INLINE_VISIBILITY const char* strstr(const char* __s1, const char* __s2) {return ::strstr(__s1, __s2);}
 inline _LIBCPP_INLINE_VISIBILITY       char* strstr(      char* __s1, const char* __s2) {return ::strstr(__s1, __s2);}
 #endif
 
-#ifndef _LIBCPP_HAS_NO_THREAD_UNSAFE_C_FUNCTIONS
-using ::strtok;
-#endif
-using ::memset;
-using ::strerror;
-using ::strlen;
-
 _LIBCPP_END_NAMESPACE_STD
 
 #endif  // _LIBCPP_CSTRING