Fix overload sets of strchr, strpbrk, strrchr, memchr and strstr from

<string.h> and wcschr, wcspbrk, wcsrchr, wmemchr, and wcsstr from <wchar.h> to
provide a const-correct overload set even when the underlying C library does
not.

This change adds a new macro, _LIBCPP_PREFERRED_OVERLOAD, which (if defined)
specifies that a given overload is a better match than an otherwise equally
good function declaration without the overload. This is implemented in modern
versions of Clang via __attribute__((enable_if)), and not elsewhere.

We use this new macro to define overloads in the global namespace for these
functions that displace the overloads provided by the C library, unless we
believe the C library is already providing the correct signatures.


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@260337 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Richard Smith
2016-02-10 00:59:02 +00:00
parent 1654db495f
commit b4aa97130b
9 changed files with 193 additions and 57 deletions

View File

@@ -78,30 +78,13 @@ using ::strcmp;
using ::strncmp;
using ::strcoll;
using ::strxfrm;
using ::memchr;
using ::strchr;
using ::strcspn;
using ::strpbrk;
using ::strrchr;
using ::strspn;
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_)
inline _LIBCPP_INLINE_VISIBILITY char* strchr( char* __s, int __c) {return ::strchr(__s, __c);}
inline _LIBCPP_INLINE_VISIBILITY char* strpbrk( char* __s1, const char* __s2) {return ::strpbrk(__s1, __s2);}
inline _LIBCPP_INLINE_VISIBILITY char* strrchr( char* __s, int __c) {return ::strrchr(__s, __c);}
inline _LIBCPP_INLINE_VISIBILITY void* memchr( void* __s, int __c, size_t __n) {return ::memchr(__s, __c, __n);}
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