[libc++] Fix support for multibyte thousands_sep and decimal_point in moneypunct_byname and numpunct_byname.

Summary:
The underlying C locales provide the `thousands_sep` and `decimal_point` as strings, possible with more than one character. We currently don't handle this case even for `wchar_t`.

This patch properly converts the mbs -> wide character for `moneypunct_byname<wchar_t>`. For the `moneypunct_byname<char>` case we attempt to narrow the WC and if that fails we also attempt to translate it to some reasonable value. For example we translate U00A0 (non-breaking space) into U0020 (regular space). If none of these conversions succeed then we simply allow the base class to provide a fallback value.


Reviewers: mclow.lists, EricWF

Subscribers: vangyzen, george.burgess.iv, cfe-commits

Differential Revision: https://reviews.llvm.org/D24218

llvm-svn: 289347
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 0d542d350dafd662fb5fe9c00b5a3e4f61ee442f
diff --git a/src/locale.cpp b/src/locale.cpp
index 88c3731..5d6ccd5 100644
--- a/src/locale.cpp
+++ b/src/locale.cpp
@@ -4183,6 +4183,54 @@
 {
 }
 
+
+static bool checked_string_to_wchar_convert(wchar_t& dest,
+                                            const char* ptr,
+                                            __locale_struct* loc) {
+  if (*ptr == '\0')
+    return false;
+  mbstate_t mb = {};
+  wchar_t out;
+  size_t ret = __libcpp_mbrtowc_l(&out, ptr, strlen(ptr), &mb, loc);
+  if (ret == static_cast<size_t>(-1) || ret == static_cast<size_t>(-2)) {
+    return false;
+  }
+  dest = out;
+  return true;
+}
+
+static bool checked_string_to_char_convert(char& dest,
+                                           const char* ptr,
+                                           __locale_struct* __loc) {
+  if (*ptr == '\0')
+    return false;
+  if (!ptr[1]) {
+    dest = *ptr;
+    return true;
+  }
+  // First convert the MBS into a wide char then attempt to narrow it using
+  // wctob_l.
+  wchar_t wout;
+  if (!checked_string_to_wchar_convert(wout, ptr, __loc))
+    return false;
+  int res;
+  if ((res = __libcpp_wctob_l(wout, __loc)) != char_traits<char>::eof()) {
+    dest = res;
+    return true;
+  }
+  // FIXME: Work around specific multibyte sequences that we can reasonable
+  // translate into a different single byte.
+  switch (wout) {
+  case L'\u00A0': // non-breaking space
+    dest = ' ';
+    return true;
+  default:
+    return false;
+  }
+  _LIBCPP_UNREACHABLE();
+}
+
+
 // numpunct<char> && numpunct<wchar_t>
 
 locale::id numpunct< char  >::id;
@@ -4254,10 +4302,10 @@
                                 " failed to construct for " + string(nm));
 
         lconv* lc = __libcpp_localeconv_l(loc.get());
-        if (*lc->decimal_point)
-            __decimal_point_ = *lc->decimal_point;
-        if (*lc->thousands_sep)
-            __thousands_sep_ = *lc->thousands_sep;
+        checked_string_to_char_convert(__decimal_point_, lc->decimal_point,
+                                       loc.get());
+        checked_string_to_char_convert(__thousands_sep_, lc->thousands_sep,
+                                       loc.get());
         __grouping_ = lc->grouping;
         // localization for truename and falsename is not available
     }
@@ -4288,16 +4336,16 @@
     {
         __locale_unique_ptr loc(newlocale(LC_ALL_MASK, nm, 0), freelocale);
         if (loc == nullptr)
-            __throw_runtime_error("numpunct_byname<char>::numpunct_byname"
+            __throw_runtime_error("numpunct_byname<wchar_t>::numpunct_byname"
                                 " failed to construct for " + string(nm));
 
         lconv* lc = __libcpp_localeconv_l(loc.get());
-        if (*lc->decimal_point)
-            __decimal_point_ = *lc->decimal_point;
-        if (*lc->thousands_sep)
-            __thousands_sep_ = *lc->thousands_sep;
+        checked_string_to_wchar_convert(__decimal_point_, lc->decimal_point,
+                                        loc.get());
+        checked_string_to_wchar_convert(__thousands_sep_, lc->thousands_sep,
+                                        loc.get());
         __grouping_ = lc->grouping;
-        // locallization for truename and falsename is not available
+        // localization for truename and falsename is not available
     }
 }
 
@@ -5779,14 +5827,15 @@
                             " failed to construct for " + string(nm));
 
     lconv* lc = __libcpp_localeconv_l(loc.get());
-    if (*lc->mon_decimal_point)
-        __decimal_point_ = *lc->mon_decimal_point;
-    else
-        __decimal_point_ = base::do_decimal_point();
-    if (*lc->mon_thousands_sep)
-        __thousands_sep_ = *lc->mon_thousands_sep;
-    else
-        __thousands_sep_ = base::do_thousands_sep();
+    if (!checked_string_to_char_convert(__decimal_point_,
+                                        lc->mon_decimal_point,
+                                        loc.get()))
+      __decimal_point_ = base::do_decimal_point();
+    if (!checked_string_to_char_convert(__thousands_sep_,
+                                        lc->mon_thousands_sep,
+                                        loc.get()))
+      __thousands_sep_ = base::do_thousands_sep();
+
     __grouping_ = lc->mon_grouping;
     __curr_symbol_ = lc->currency_symbol;
     if (lc->frac_digits != CHAR_MAX)
@@ -5822,14 +5871,14 @@
                             " failed to construct for " + string(nm));
 
     lconv* lc = __libcpp_localeconv_l(loc.get());
-    if (*lc->mon_decimal_point)
-        __decimal_point_ = *lc->mon_decimal_point;
-    else
-        __decimal_point_ = base::do_decimal_point();
-    if (*lc->mon_thousands_sep)
-        __thousands_sep_ = *lc->mon_thousands_sep;
-    else
-        __thousands_sep_ = base::do_thousands_sep();
+    if (!checked_string_to_char_convert(__decimal_point_,
+                                        lc->mon_decimal_point,
+                                        loc.get()))
+      __decimal_point_ = base::do_decimal_point();
+    if (!checked_string_to_char_convert(__thousands_sep_,
+                                        lc->mon_thousands_sep,
+                                        loc.get()))
+      __thousands_sep_ = base::do_thousands_sep();
     __grouping_ = lc->mon_grouping;
     __curr_symbol_ = lc->int_curr_symbol;
     if (lc->int_frac_digits != CHAR_MAX)
@@ -5881,14 +5930,14 @@
         __throw_runtime_error("moneypunct_byname"
                             " failed to construct for " + string(nm));
     lconv* lc = __libcpp_localeconv_l(loc.get());
-    if (*lc->mon_decimal_point)
-        __decimal_point_ = static_cast<wchar_t>(*lc->mon_decimal_point);
-    else
-        __decimal_point_ = base::do_decimal_point();
-    if (*lc->mon_thousands_sep)
-        __thousands_sep_ = static_cast<wchar_t>(*lc->mon_thousands_sep);
-    else
-        __thousands_sep_ = base::do_thousands_sep();
+    if (!checked_string_to_wchar_convert(__decimal_point_,
+                                         lc->mon_decimal_point,
+                                         loc.get()))
+      __decimal_point_ = base::do_decimal_point();
+    if (!checked_string_to_wchar_convert(__thousands_sep_,
+                                         lc->mon_thousands_sep,
+                                         loc.get()))
+      __thousands_sep_ = base::do_thousands_sep();
     __grouping_ = lc->mon_grouping;
     wchar_t wbuf[100];
     mbstate_t mb = {0};
@@ -5947,14 +5996,14 @@
                             " failed to construct for " + string(nm));
 
     lconv* lc = __libcpp_localeconv_l(loc.get());
-    if (*lc->mon_decimal_point)
-        __decimal_point_ = static_cast<wchar_t>(*lc->mon_decimal_point);
-    else
-        __decimal_point_ = base::do_decimal_point();
-    if (*lc->mon_thousands_sep)
-        __thousands_sep_ = static_cast<wchar_t>(*lc->mon_thousands_sep);
-    else
-        __thousands_sep_ = base::do_thousands_sep();
+    if (!checked_string_to_wchar_convert(__decimal_point_,
+                                         lc->mon_decimal_point,
+                                         loc.get()))
+      __decimal_point_ = base::do_decimal_point();
+    if (!checked_string_to_wchar_convert(__thousands_sep_,
+                                         lc->mon_thousands_sep,
+                                         loc.get()))
+      __thousands_sep_ = base::do_thousands_sep();
     __grouping_ = lc->mon_grouping;
     wchar_t wbuf[100];
     mbstate_t mb = {0};