[libc++][test] Update some wstring_convert tests for MSVC quirks

[CaseyCarter]

Summary

Due to MSVC's decision to encode wchar_t as UTF-16, it rejects wide character/string literals that expect a character value greater than \xffff. UTF-16 wchar_t is clearly non-conforming, given that the standard requires wchar_t to be capable of representing all characters in the supported wide character execution sets, but rejecting e.g. \x40003 is a reasonably sane compromise given that encoding choice: there's an expectation that \xFOO produces a single character in the resulting literal. Consequently L'\x40003'/L"\x40003" are ill-formed literals on MSVC. L'\U00040003' is a high surrogate (and produces a warning about ignoring the "second character" in a multi-character literal), and L"\U00040003" is a perfectly-valid const wchar_t[3].

This change updates these tests to use universal-character-names instead of raw values for the intended character values, which technically makes them portable even to implementations that don't use a unicode transformation format encoding for their wide character execution character set. The two-character literal L"\u1005e" is awkward - the e looks like part of the UCN's hex encoding - but necessary to compile in '03 mode since '03 didn't allow UCNs to be used for members of the basic execution character set even in character/string literals.

I've also eliminated the extraneous \x00 "bonus null-terminator" in some of the string literals which doesn't affect the tested behavior. I'm sorry about using *L"\U00040003" in conversions.string/to_bytes.pass.cpp, but it's correct for platforms with 32-bit wchar_t, *and* doesn't trigger narrowing warnings as did the prior CharT(0x40003).

[mclow.lists]

I think you failed to paste a bit into the description of this patch (after the first sentence, before the second).

Does the "universal character names" stuff work on old standards? (C++11/03) and old compilers?

[CaseyCarter]

In D60950#1474050, @mclow.lists wrote:

I think you failed to paste a bit into the description of this patch (after the first sentence, before the second).

Reworded. Is that more clear?

Does the "universal character names" stuff work on old standards? (C++11/03) and old compilers?

UCNs were in '98. '11 relaxed the restriction that a UCN could not name a member of the basic execution character set or a control character to only apply outside of string and character literals. The tests pass with clang 3.6 (the oldest I have readily available) in '03 mode, and gcc-4.9 in '11 mode. GCC won't compile the test in '03 mode due to the use of default template arguments in <memory> and <string>.

[mclow.lists]

In D60950#1474156, @CaseyCarter wrote:

In D60950#1474050, @mclow.lists wrote:

I think you failed to paste a bit into the description of this patch (after the first sentence, before the second).

Reworded. Is that more clear?

Yes, thank you.

test/std/localization/locales/locale.convenience/conversions/conversions.string/converted.pass.cpp

 template <class CharT>
 void TestHelper<CharT, 2>::test() {
   static_assert((std::is_same<CharT, wchar_t>::value), "");
   {
     typedef std::codecvt_utf8<CharT> Codecvt;
     typedef std::wstring_convert<Codecvt> Myconv;
     Myconv myconv;
     assert(myconv.converted() == 0);
-    std::string bs = myconv.to_bytes(L"\x1005");
+    std::string bs = myconv.to_bytes(L"\u1005");
     assert(myconv.converted() == 1);
-    bs = myconv.to_bytes(L"\x1005\x65");
+    bs = myconv.to_bytes(L"\u1005e");
     assert(myconv.converted() == 2);
     std::wstring ws = myconv.from_bytes("\xE1\x80\x85");
     assert(myconv.converted() == 3);
   }
 }
 
 template <class CharT>
 void TestHelper<CharT, 4>::test() {
   static_assert((std::is_same<CharT, wchar_t>::value), "");
   {
     typedef std::codecvt_utf8<CharT> Codecvt;
     typedef std::wstring_convert<Codecvt> Myconv;
     Myconv myconv;
     assert(myconv.converted() == 0);
-    std::string bs = myconv.to_bytes(L"\x40003");
+    std::string bs = myconv.to_bytes(L"\U00040003");
     assert(myconv.converted() == 1);
-    bs = myconv.to_bytes(L"\x40003\x65");
+    bs = myconv.to_bytes(L"\U00040003e");
     assert(myconv.converted() == 2);
     std::wstring ws = myconv.from_bytes("\xF1\x80\x80\x83");
     assert(myconv.converted() == 4);
   }
 }
 
-int main(int, char**) { TestHelper<wchar_t>::test(); 
+int main(int, char**) {
+  TestHelper<wchar_t>::test();
   return 0;
 }

test/std/localization/locales/locale.convenience/conversions/conversions.string/from_bytes.pass.cpp

struct TestHelper<CharT, 4> {
   static void test();
 };
 
 template <class CharT>
 void TestHelper<CharT, 2>::test() {
   static_assert((std::is_same<CharT, wchar_t>::value), "");
   {
     std::wstring_convert<std::codecvt_utf8<CharT> > myconv;
-    std::string bs("\xE1\x80\x85\x00");
+    std::string bs("\xE1\x80\x85");
     std::wstring ws = myconv.from_bytes('a');
     assert(ws == L"a");
     ws = myconv.from_bytes(bs.c_str());
-    assert(ws == L"\x1005");
+    assert(ws == L"\u1005");
     ws = myconv.from_bytes(bs);
-    assert(ws == L"\x1005");
+    assert(ws == L"\u1005");
     ws = myconv.from_bytes(bs.data(), bs.data() + bs.size());
-    assert(ws == L"\x1005");
+    assert(ws == L"\u1005");
     ws = myconv.from_bytes("");
     assert(ws.size() == 0);
   }
 }
 
 template <class CharT>
 void TestHelper<CharT, 4>::test() {
   static_assert((std::is_same<CharT, wchar_t>::value), "");
   {
     std::wstring_convert<std::codecvt_utf8<CharT> > myconv;
     std::string bs("\xF1\x80\x80\x83");
     std::wstring ws = myconv.from_bytes('a');
     assert(ws == L"a");
     ws = myconv.from_bytes(bs.c_str());
-    assert(ws == L"\x40003");
+    assert(ws == L"\U00040003");
     ws = myconv.from_bytes(bs);
-    assert(ws == L"\x40003");
+    assert(ws == L"\U00040003");
     ws = myconv.from_bytes(bs.data(), bs.data() + bs.size());
-    assert(ws == L"\x40003");
+    assert(ws == L"\U00040003");
     ws = myconv.from_bytes("");
     assert(ws.size() == 0);
   }
 }
 
-int main(int, char**) { TestHelper<wchar_t>::test(); 
+int main(int, char**) {
+  TestHelper<wchar_t>::test();
   return 0;
 }

test/std/localization/locales/locale.convenience/conversions/conversions.string/to_bytes.pass.cpp

struct TestHelper<CharT, 4> {
   static void test();
 };
 
 template <class CharT>
 void TestHelper<CharT, 2>::test() {
   static_assert((std::is_same<CharT, wchar_t>::value), "");
   {
     std::wstring_convert<std::codecvt_utf8<CharT> > myconv;
-    std::wstring ws(1, CharT(0x1005));
+    std::wstring ws(1, L'\u1005');
     std::string bs = myconv.to_bytes(ws[0]);
-    assert(bs == "\xE1\x80\x85\x00");
+    assert(bs == "\xE1\x80\x85");
     bs = myconv.to_bytes(ws.c_str());
-    assert(bs == "\xE1\x80\x85\x00");
+    assert(bs == "\xE1\x80\x85");
     bs = myconv.to_bytes(ws);
-    assert(bs == "\xE1\x80\x85\x00");
+    assert(bs == "\xE1\x80\x85");
     bs = myconv.to_bytes(ws.data(), ws.data() + ws.size());
-    assert(bs == "\xE1\x80\x85\x00");
+    assert(bs == "\xE1\x80\x85");
     bs = myconv.to_bytes(L"");
     assert(bs.size() == 0);
   }
 }
 
 template <class CharT>
 void TestHelper<CharT, 4>::test() {
   static_assert((std::is_same<CharT, wchar_t>::value), "");
   {
     std::wstring_convert<std::codecvt_utf8<CharT> > myconv;
-    std::wstring ws(1, CharT(0x40003));
+    std::wstring ws(1, *L"\U00040003");
     std::string bs = myconv.to_bytes(ws[0]);
     assert(bs == "\xF1\x80\x80\x83");
     bs = myconv.to_bytes(ws.c_str());
     assert(bs == "\xF1\x80\x80\x83");
     bs = myconv.to_bytes(ws);
     assert(bs == "\xF1\x80\x80\x83");
     bs = myconv.to_bytes(ws.data(), ws.data() + ws.size());
     assert(bs == "\xF1\x80\x80\x83");
     bs = myconv.to_bytes(L"");
     assert(bs.size() == 0);
   }
 }
 
-int main(int, char**) { TestHelper<wchar_t>::test(); 
+int main(int, char**) {
+  TestHelper<wchar_t>::test();
   return 0;
 }