Replace qdtoa and qstrtod implementation by a 3rdparty library

This also fixes the underlying cause of QTBUG-44039 and QTBUG-43885.

You can choose between system, qt, and no libdouble-conversion
support. If you choose "no", snprintf_l and sscanf_l will be
used.

By default, system double conversion is used if the system provides a
double-conversion library. Otherwise the bundled libdouble-conversion
is built. sscanf_l and snprintf_l are not used by default as the
planned "shortest" conversion mode to produce the shortest possible
string will give less precise results when implemented with snprintf_l.

Change-Id: I8ca08a0fca5c54cf7009e48e771385614f6aa031
Reviewed-by: Simon Hausmann <simon.hausmann@theqtcompany.com>

2 files changed, 44 insertions, 0 deletions

diff --git a/config.tests/unix/doubleconversion/doubleconversion.cpp b/config.tests/unix/doubleconversion/doubleconversion.cpp
new file mode 100644
index 0000000000..4bf14a5b36
--- /dev/null
+++ b/config.tests/unix/doubleconversion/doubleconversion.cpp
@@ -0,0 +1,40 @@
+/****************************************************************************
+**
+** Copyright (C) 2015 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the config.tests of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL21$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 or version 3 as published by the Free
+** Software Foundation and appearing in the file LICENSE.LGPLv21 and
+** LICENSE.LGPLv3 included in the packaging of this file. Please review the
+** following information to ensure the GNU Lesser General Public License
+** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** As a special exception, The Qt Company gives you certain additional
+** rights. These rights are described in The Qt Company LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <double-conversion/double-conversion.h>
+
+int main(int, char **)
+{
+    int flags = double_conversion::StringToDoubleConverter::NO_FLAGS;
+    return flags;
+}
diff --git a/config.tests/unix/doubleconversion/doubleconversion.pro b/config.tests/unix/doubleconversion/doubleconversion.pro
new file mode 100644
index 0000000000..ae435b9293
--- /dev/null
+++ b/config.tests/unix/doubleconversion/doubleconversion.pro
@@ -0,0 +1,4 @@
+SOURCES = doubleconversion.cpp
+CONFIG -= qt
+CONFIG += console
+LIBS += -ldouble-conversion