QString::fromUcs4: use std::char_traits or wcslen() to find the size

... when the user passes size = -1. std::char_traits<char32_t>::length() doesn't appear to be an any better implementation than our simple loop, but maybe some compiler will optimize it. wcslen() is usually optimized in the C libraries, even for Unix platforms that hardly ever use it (it's used as a fallback in qustrlen() for non-x86 Windows systems). Pick-to: 6.8 6.9 Change-Id: Ia143270869a3a7cf5754fffdc17e500fc454397b Reviewed-by: Edward Welbourne <[email protected]>
qt · Dec 12, 2024 · b98cf4f · b98cf4f
1 parent 973d0c4
commit b98cf4f
Showing 1 changed file with 4 additions and 3 deletions.
diff --git a/src/corelib/text/qstring.cpp b/src/corelib/text/qstring.cpp
@@ -6115,9 +6115,10 @@ QString QString::fromUcs4(const char32_t *unicode, qsizetype size)
     if (!unicode)
         return QString();
     if (size < 0) {
-        size = 0;
-        while (unicode[size] != 0)
-            ++size;
+        if constexpr (sizeof(char32_t) == sizeof(wchar_t))
+            size = wcslen(reinterpret_cast<const wchar_t *>(unicode));
+        else
+            size = std::char_traits<char32_t>::length(unicode);
     }
     QStringDecoder toUtf16(QStringDecoder::Utf32, QStringDecoder::Flag::Stateless);
     return toUtf16(QByteArrayView(reinterpret_cast<const char *>(unicode), size * 4));