QString: skip QLocale::numberToCLocale for floating point

This is a repeat of commit 885ae61c6378e06a965f543d2ecbd162c6224347,
which applied a direct QString-to-Latin1 conversion to integral parsing
to avoid going through the expensive QLocale::numberToCLocale. But we
also need to lowercase the input.

Change-Id: Ieba79baf5ac34264a988fffd1726762a411e3bd6
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

1 files changed, 16 insertions, 1 deletions

diff --git a/src/corelib/text/qstring.cpp b/src/corelib/text/qstring.cpp
index f954e8b25d..b3e147c0ba 100644
--- a/src/corelib/text/qstring.cpp
+++ b/src/corelib/text/qstring.cpp
@@ -7487,7 +7487,22 @@ double QString::toDouble(bool *ok) const
 
 double QStringView::toDouble(bool *ok) const
 {
-    return QLocaleData::c()->stringToDouble(*this, ok, QLocale::RejectGroupSeparator);
+    QStringView string = qt_trimmed(*this);
+    QVarLengthArray<uchar> latin1(string.size());
+    qt_to_latin1(latin1.data(), string.utf16(), string.size());
+
+    // We need lowetcased "inf" and "nan".
+    // This mangles the string, but nothing can become a number or letter
+    // that isn't already a number or letter.
+    for (uchar &c : latin1) {
+        if (c >= 'A')
+            c |= 0x20;
+    }
+
+    auto r = qt_asciiToDouble(reinterpret_cast<const char *>(latin1.data()), string.size());
+    if (ok != nullptr)
+        *ok = r.ok();
+    return r.result;
 }
 
 /*!