QAnyStringView: support single wchar_t arguments also on UnixHEADdev

We support char32_t, so there's no reason to not support a
4-byte-wchar_t.

This also fixes a nasty asymmery between QString::arg(L'ä') (integral
output) and QL1SV::arg(L'ä') or QString::arg(L'ä', L'ä') (characters)

[ChangeLog][Important Behavior Changes][QtCore][QString] The unary
arg() function now treats wchar_t as a character (string-like; was:
integer), so u"%1".arg(L'ø') will now return "ø" and not '248". This
makes the function consistent with both QString multi-arg() and
QLatin1StringView::arg().

[ChangeLog][QtCore][QAnyStringView] Supports construction from a
single wchar_t on all platforms now (was: only on Windows).

Fixes: QTBUG-126054
Pick-to: 6.10
Change-Id: I21b7a9782f03d04686207db30d1b1c9d50bc8169
Reviewed-by: Thiago Macieira <[email protected]>

6 files changed, 32 insertions, 9 deletions

diff --git a/src/corelib/text/qanystringview.cpp b/src/corelib/text/qanystringview.cpp
index 717b53f06c2..7bf8a3fa1fd 100644
--- a/src/corelib/text/qanystringview.cpp
+++ b/src/corelib/text/qanystringview.cpp
@@ -138,6 +138,7 @@ QT_BEGIN_NAMESPACE
     \list
     \li \c QLatin1Char
     \li \c QChar::SpecialCharacter
+    \li \c wchar_t (where it's a 32-bit type, i.e. Unix) (since 6.10)
     \li \c char32_t
     \endlist
 
diff --git a/src/corelib/text/qanystringview.h b/src/corelib/text/qanystringview.h
index 4b89fa6edbf..079cf751af1 100644
--- a/src/corelib/text/qanystringview.h
+++ b/src/corelib/text/qanystringview.h
@@ -25,6 +25,11 @@ struct wrapped { using type = Result; };
 template <typename Tag, typename Result>
 using wrapped_t = typename wrapped<Tag, Result>::type;
 
+template <typename Char>
+struct is_compatible_utf32_char : std::false_type {};
+template <> struct is_compatible_utf32_char<char32_t> : std::true_type {};
+template <> struct is_compatible_utf32_char<wchar_t> : std::bool_constant<sizeof(wchar_t) == 4> {};
+
 } // namespace QtPrivate
 
 class QAnyStringView
@@ -60,6 +65,11 @@ private:
     };
 
     template <typename Char>
+    using if_compatible_utf32_char = std::enable_if_t<
+        QtPrivate::is_compatible_utf32_char<Char>::value
+    , bool>;
+
+    template <typename Char>
     using is_compatible_char = std::disjunction<
         QtPrivate::IsCompatibleCharType<Char>,
         QtPrivate::IsCompatibleChar8Type<Char>
@@ -220,7 +230,7 @@ public:
     constexpr QAnyStringView(Char ch, QCharContainer &&capacity = QCharContainer()) noexcept
         : QAnyStringView{&(capacity.ch = ch), 1} {}
     template <typename Char, typename Container = decltype(QChar::fromUcs4(U'x')),
-              std::enable_if_t<std::is_same_v<Char, char32_t>, bool> = true>
+              if_compatible_utf32_char<Char> = true>
     constexpr QAnyStringView(Char c, Container &&capacity = {}) noexcept
         : QAnyStringView(capacity = QChar::fromUcs4(c)) {}
 
diff --git a/src/corelib/text/qstring.h b/src/corelib/text/qstring.h
index 09cfbdfe94d..e4f06835bd1 100644
--- a/src/corelib/text/qstring.h
+++ b/src/corelib/text/qstring.h
@@ -66,9 +66,6 @@ template <> struct treat_as_integral_arg<unsigned short> : std::true_type {};
 template <> struct treat_as_integral_arg<  signed short> : std::true_type {};
 template <> struct treat_as_integral_arg<unsigned  char> : std::true_type {};
 template <> struct treat_as_integral_arg<  signed  char> : std::true_type {};
-// QTBUG-126054, keep until we can fix it for all platforms, not just Windows
-// (where wchar_t does convert to QAnyStringView):
-template <> struct treat_as_integral_arg<wchar_t> : std::true_type {};
 }
 
 // Qt 4.x compatibility
diff --git a/tests/auto/corelib/text/qanystringview/tst_qanystringview.cpp b/tests/auto/corelib/text/qanystringview/tst_qanystringview.cpp
index 8c129a93c71..d976191406d 100644
--- a/tests/auto/corelib/text/qanystringview/tst_qanystringview.cpp
+++ b/tests/auto/corelib/text/qanystringview/tst_qanystringview.cpp
@@ -242,7 +242,7 @@ constexpr bool CanConvertFromWCharT =
 #endif
         ;
 
-static_assert(CanConvert<wchar_t> == CanConvertFromWCharT); // ### FIXME: should work everywhere
+static_assert(CanConvert<wchar_t>);
 
 static_assert(CanConvert<      wchar_t[123]> == CanConvertFromWCharT);
 static_assert(CanConvert<const wchar_t[123]> == CanConvertFromWCharT);
@@ -414,7 +414,10 @@ private Q_SLOTS:
         fromCharacter(U'\x1F0A0', 2, true); // U+1F0A0: PLAYING CARD BACK
     }
     void fromWCharT() const {
-        ONLY_WIN(fromCharacter(L'ä', 1)); // should work on Unix, too (char32_t does)
+        fromCharacter(L'ä', 1, sizeof(L'ä') == sizeof(char32_t));
+#ifndef Q_OS_WIN // sizedof(wchar_t) == 2 on Windows, so L'\x1F0A0' would be out-of-range
+        fromCharacter(L'\x1F0A0', 2, true); // U+1F0A0: PLAYING CARD BACK
+#endif
     }
     void fromQChar() const { fromCharacter(QChar(u'ä'), 1); }
     void fromQLatin1Char() const { fromCharacter(QLatin1Char('\xE4'), 1, true); }
diff --git a/tests/auto/corelib/text/qstring/tst_qstring.cpp b/tests/auto/corelib/text/qstring/tst_qstring.cpp
index cfc0ec1cc07..2cd1398e7f9 100644
--- a/tests/auto/corelib/text/qstring/tst_qstring.cpp
+++ b/tests/auto/corelib/text/qstring/tst_qstring.cpp
@@ -6859,10 +6859,7 @@ void tst_QString::arg()
     // char-ish overloads
     QCOMPARE(s4.arg('\xE4'), QStringView(u"[ä]"));
     QCOMPARE(s4.arg(u'ø'), QStringView(u"[ø]"));
-#ifdef Q_OS_WIN
     QCOMPARE(QLatin1String("[%1]").arg(L'ø'), QStringView(u"[ø]"));
-#endif
-    QEXPECT_FAIL("", "QTBUG-126054", Continue);
     QCOMPARE(s4.arg(L'ø'), QStringView(u"[ø]"));
 #ifndef __cpp_char8_t
 #ifndef QT_NO_CAST_FROM_ASCII
diff --git a/tests/auto/corelib/text/qstringapisymmetry/tst_qstringapisymmetry.cpp b/tests/auto/corelib/text/qstringapisymmetry/tst_qstringapisymmetry.cpp
index 0b2aaa8281e..7b5b468df0d 100644
--- a/tests/auto/corelib/text/qstringapisymmetry/tst_qstringapisymmetry.cpp
+++ b/tests/auto/corelib/text/qstringapisymmetry/tst_qstringapisymmetry.cpp
@@ -603,6 +603,8 @@ private Q_SLOTS:
     void arg1_QString_char16_t() {
         arg1_impl<QString, char16_t>();
     }
+    void arg1_QString_wchar_t_data() { arg1_data(false); }
+    void arg1_QString_wchar_t() { arg1_impl<QString, wchar_t>(); }
 
     void arg1_QStringView_QString_data() { arg1_data(); }
     void arg1_QStringView_QString() { arg1_impl<QStringView, QString>(); }
@@ -638,6 +640,8 @@ private Q_SLOTS:
     void arg1_QStringView_QLatin1Char() { arg1_impl<QStringView, QLatin1Char>(); }
     void arg1_QStringView_char16_t_data() { arg1_data(false); }
     void arg1_QStringView_char16_t() { arg1_impl<QStringView, char16_t>(); }
+    void arg1_QStringView_wchar_t_data() { arg1_data(false); }
+    void arg1_QStringView_wchar_t() { arg1_impl<QStringView, wchar_t>(); }
 
     void arg1_QLatin1StringView_QString_data() { arg1_data(); }
     void arg1_QLatin1StringView_QString() { arg1_impl<QLatin1StringView, QString>(); }
@@ -673,6 +677,8 @@ private Q_SLOTS:
     void arg1_QLatin1StringView_QLatin1Char() { arg1_impl<QLatin1StringView, QLatin1Char>(); }
     void arg1_QLatin1StringView_char16_t_data() { arg1_data(false); }
     void arg1_QLatin1StringView_char16_t() { arg1_impl<QLatin1StringView, char16_t>(); }
+    void arg1_QLatin1StringView_wchar_t_data() { arg1_data(false); }
+    void arg1_QLatin1StringView_wchar_t() { arg1_impl<QLatin1StringView, wchar_t>(); }
 
     void arg1_QUtf8StringView_QString_data() { arg1_data(); }
     void arg1_QUtf8StringView_QString() { arg1_impl<QUtf8StringView, QString>(); }
@@ -708,6 +714,8 @@ private Q_SLOTS:
     void arg1_QUtf8StringView_QLatin1Char() { arg1_impl<QUtf8StringView, QLatin1Char>(); }
     void arg1_QUtf8StringView_char16_t_data() { arg1_data(false); }
     void arg1_QUtf8StringView_char16_t() { arg1_impl<QUtf8StringView, char16_t>(); }
+    void arg1_QUtf8StringView_wchar_t_data() { arg1_data(false); }
+    void arg1_QUtf8StringView_wchar_t() { arg1_impl<QUtf8StringView, wchar_t>(); }
 
     void arg1_QAnyStringViewUsingL1_QString_data() { arg1_data(); }
     void arg1_QAnyStringViewUsingL1_QString() { arg1_impl<QAnyStringViewUsingL1, QString>(); }
@@ -743,6 +751,8 @@ private Q_SLOTS:
     void arg1_QAnyStringViewUsingL1_QLatin1Char() { arg1_impl<QAnyStringViewUsingL1, QLatin1Char>(); }
     void arg1_QAnyStringViewUsingL1_char16_t_data() { arg1_data(false); }
     void arg1_QAnyStringViewUsingL1_char16_t() { arg1_impl<QAnyStringViewUsingL1, char16_t>(); }
+    void arg1_QAnyStringViewUsingL1_wchar_t_data() { arg1_data(false); }
+    void arg1_QAnyStringViewUsingL1_wchar_t() { arg1_impl<QAnyStringViewUsingL1, wchar_t>(); }
 
     void arg1_QAnyStringViewUsingU8_QString_data() { arg1_data(); }
     void arg1_QAnyStringViewUsingU8_QString() { arg1_impl<QAnyStringViewUsingU8, QString>(); }
@@ -778,6 +788,8 @@ private Q_SLOTS:
     void arg1_QAnyStringViewUsingU8_QLatin1Char() { arg1_impl<QAnyStringViewUsingU8, QLatin1Char>(); }
     void arg1_QAnyStringViewUsingU8_char16_t_data() { arg1_data(false); }
     void arg1_QAnyStringViewUsingU8_char16_t() { arg1_impl<QAnyStringViewUsingU8, char16_t>(); }
+    void arg1_QAnyStringViewUsingU8_wchar_t_data() { arg1_data(false); }
+    void arg1_QAnyStringViewUsingU8_wchar_t() { arg1_impl<QAnyStringViewUsingU8, wchar_t>(); }
 
     void arg1_QAnyStringViewUsingU16_QString_data() { arg1_data(); }
     void arg1_QAnyStringViewUsingU16_QString() { arg1_impl<QAnyStringViewUsingU16, QString>(); }
@@ -813,6 +825,8 @@ private Q_SLOTS:
     void arg1_QAnyStringViewUsingU16_QLatin1Char() { arg1_impl<QAnyStringViewUsingU16, QLatin1Char>(); }
     void arg1_QAnyStringViewUsingU16_char16_t_data() { arg1_data(false); }
     void arg1_QAnyStringViewUsingU16_char16_t() { arg1_impl<QAnyStringViewUsingU16, char16_t>(); }
+    void arg1_QAnyStringViewUsingU16_wchar_t_data() { arg1_data(false); }
+    void arg1_QAnyStringViewUsingU16_wchar_t() { arg1_impl<QAnyStringViewUsingU16, wchar_t>(); }
 
 private:
     void split_data(bool rhsHasVariableLength = true);
@@ -1627,6 +1641,7 @@ template <class Str> Str  make(QStringView sf, QLatin1String l1, const QByteArra
 MAKE(QChar)                  { return sv.isEmpty() ? QChar() : sv.at(0); }
 MAKE(char)                   { return sv.isEmpty() ? char() : char(sv.at(0).unicode()); }
 MAKE(char16_t)               { return sv.isEmpty() ? char16_t() : char16_t{sv.at(0).unicode()}; }
+MAKE(wchar_t)                { return make<char16_t>(sv, l1, u8); }
 MAKE(QLatin1Char)            { return l1.isEmpty() ? QLatin1Char('\0') : l1.at(0); }
 MAKE(QString)                { return sv.toString(); }
 MAKE(QStringView)            { return sv; }