Remove mblen(), mbtowc() and wctomb() from the thread-unsafe functions.

EdSchouten · EdSchouten · commit 0a92402436d0 · 2016-12-30T10:44:00.000Z
Back in r240527 I added a knob to prevent thread-unsafe functions from being exposed. mblen(), mbtowc() and wctomb() were also added to this list, as the latest issue of POSIX doesn't require these functions to be thread-safe. It turns out that the only circumstance in which these functions are not thread-safe is in case they are used in combination with state-dependent character sets (e.g., Shift-JIS). According to Austin Group Bug 708, these character sets "[...] are mostly a relic of the past and which were never supported on most POSIX systems". Though in many cases the use of these functions can be prevented by using the reentrant counterparts, they are the only functions that allow you to query whether the locale's character set is state-dependent. This means that omitting these functions removes actual functionality. Let's be a bit less pedantic and drop the guards around these functions. Links: http://austingroupbugs.net/view.php?id=708 http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2037.htm Reviewed by: ericwf Differential Revision: https://reviews.llvm.org/D21436 llvm-svn: 290748
diff --git a/libcxx/include/__config b/libcxx/include/__config
@@ -917,7 +917,7 @@ _LIBCPP_FUNC_VIS extern "C" void __sanitizer_annotate_contiguous_container(
 #define _LIBCPP_PROVIDES_DEFAULT_RUNE_TABLE
 #endif
 
-// Thread-unsafe functions such as strtok(), mbtowc() and localtime()
+// Thread-unsafe functions such as strtok() and localtime()
 // are not available.
 #ifdef __CloudABI__
 #define _LIBCPP_HAS_NO_THREAD_UNSAFE_C_FUNCTIONS
diff --git a/libcxx/include/cstdlib b/libcxx/include/cstdlib
@@ -144,11 +144,9 @@ using ::ldiv;
 #ifndef _LIBCPP_HAS_NO_LONG_LONG
 using ::lldiv;
 #endif // _LIBCPP_HAS_NO_LONG_LONG
-#ifndef _LIBCPP_HAS_NO_THREAD_UNSAFE_C_FUNCTIONS
 using ::mblen;
 using ::mbtowc;
 using ::wctomb;
-#endif
 using ::mbstowcs;
 using ::wcstombs;
 #ifdef _LIBCPP_HAS_QUICK_EXIT
diff --git a/libcxx/test/std/depr/depr.c.headers/stdlib_h.pass.cpp b/libcxx/test/std/depr/depr.c.headers/stdlib_h.pass.cpp
@@ -104,11 +104,9 @@ int main()
     wchar_t* pw = 0;
     const wchar_t* pwc = 0;
     char* pc = 0;
-#ifndef _LIBCPP_HAS_NO_THREAD_UNSAFE_C_FUNCTIONS
     static_assert((std::is_same<decltype(mblen("",0)), int>::value), "");
     static_assert((std::is_same<decltype(mbtowc(pw,"",0)), int>::value), "");
     static_assert((std::is_same<decltype(wctomb(pc,L' ')), int>::value), "");
-#endif
     static_assert((std::is_same<decltype(mbstowcs(pw,"",0)), size_t>::value), "");
     static_assert((std::is_same<decltype(wcstombs(pc,pwc,0)), size_t>::value), "");
 }
diff --git a/libcxx/test/std/language.support/support.runtime/cstdlib.pass.cpp b/libcxx/test/std/language.support/support.runtime/cstdlib.pass.cpp
@@ -96,11 +96,9 @@ int main()
     wchar_t* pw = 0;
     const wchar_t* pwc = 0;
     char* pc = 0;
-#ifndef _LIBCPP_HAS_NO_THREAD_UNSAFE_C_FUNCTIONS
     static_assert((std::is_same<decltype(std::mblen("",0)), int>::value), "");
     static_assert((std::is_same<decltype(std::mbtowc(pw,"",0)), int>::value), "");
     static_assert((std::is_same<decltype(std::wctomb(pc,L' ')), int>::value), "");
-#endif
     static_assert((std::is_same<decltype(std::mbstowcs(pw,"",0)), std::size_t>::value), "");
     static_assert((std::is_same<decltype(std::wcstombs(pc,pwc,0)), std::size_t>::value), "");
 }
