[libcxx] Fix the error checking for wctob_l, fixing locale narrow function on Windows

According to POSIX.1 (and Glibc docs, and Microsoft docs), the wctob
function returns EOF on error, not WEOF. (And wctob_l should consequently
do the same.)

The previous misconception about what this function returns on errors
seems to stem from incorrect documentation in macOS, stemming from BSD
docs with the same issue. The corresponding documentation bug in FreeBSD
was fixed in 2012 in
https://github.com/freebsd/freebsd-src/commit/945aab90991bdaeabeb6ef25112975a96c01dd4e,
but it hasn't been fixed for macOS yet.

The issue seems to only be a documentation issue; the implementation
on macOS actually does use EOF, not WEOF:
https://opensource.apple.com/source/Libc/Libc-1439.40.11/locale/FreeBSD/wctob.c.auto.html

On most Unices, EOF and WEOF are the same value, but on Windows,
EOF is -1, while WEOF is (unsigned short)0xFFFF. By fixing this,
two tests start passing on Windows.

Differential Revision: https://reviews.llvm.org/D120088

diff --git a/libcxx/src/locale.cpp b/libcxx/src/locale.cpp
index bd3f873..fd0e17a 100644 (file)
--- a/libcxx/src/locale.cpp
+++ b/libcxx/src/locale.cpp
@@ -1524,7 +1524,7 @@ char
 ctype_byname<wchar_t>::do_narrow(char_type c, char dfault) const
 {
     int r = __libcpp_wctob_l(c, __l);
-    return r != static_cast<int>(WEOF) ? static_cast<char>(r) : dfault;
+    return (r != EOF) ? static_cast<char>(r) : dfault;
 }
 
 const wchar_t*
@@ -1533,7 +1533,7 @@ ctype_byname<wchar_t>::do_narrow(const char_type* low, const char_type* high, ch
     for (; low != high; ++low, ++dest)
     {
         int r = __libcpp_wctob_l(*low, __l);
-        *dest = r != static_cast<int>(WEOF) ? static_cast<char>(r) : dfault;
+        *dest = (r != EOF) ? static_cast<char>(r) : dfault;
     }
     return low;
 }

diff --git a/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/narrow_1.pass.cpp b/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/narrow_1.pass.cpp
index 2c2f9b6..c4cb4f7 100644 (file)
--- a/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/narrow_1.pass.cpp
+++ b/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/narrow_1.pass.cpp
@@ -8,7 +8,6 @@
 
 // REQUIRES: locale.en_US.UTF-8
 // REQUIRES: locale.fr_CA.ISO8859-1
-// XFAIL: LIBCXX-WINDOWS-FIXME
 // XFAIL: libcpp-has-no-wide-characters
 
 // <locale>

diff --git a/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/narrow_many.pass.cpp b/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/narrow_many.pass.cpp
index 8cb1e22..1442f1a 100644 (file)
--- a/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/narrow_many.pass.cpp
+++ b/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/narrow_many.pass.cpp
@@ -8,7 +8,6 @@
 
 // REQUIRES: locale.en_US.UTF-8
 // REQUIRES: locale.fr_CA.ISO8859-1
-// XFAIL: LIBCXX-WINDOWS-FIXME
 // XFAIL: libcpp-has-no-wide-characters
 
 // <locale>