Fix QSettings parsing of spaces after comment lines

[ChangeLog][QtCore][QSettings] Fixed QSettings parsing of blank spaces
after comment lines in INI-style configuration files.

Fixes: QTBUG-72007
Change-Id: Idd0c85a4e7b64f9c9c7dfffd156c5b219f3b5c0a
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>

src/corelib/io/qsettings.cpp

@@ -1634,6 +1634,8 @@ bool QConfFileSettingsPrivate::readIniLine(const QByteArray &data, int &dataPos,
                 char ch;
                 while (i < dataLen && (((ch = data.at(i)) != '\n') && ch != '\r'))
                     ++i;
+                while (i < dataLen && charTraits[uchar(data.at(i))] & Space)
+                    ++i;
                 lineStart = i;
             } else if (!inQuotes) {
                 --i;

tests/auto/corelib/io/qsettings/qsettings.qrc

@@ -7,5 +7,6 @@
         <file>resourcefile5.ini</file>
         <file>resourcefile6.plist</file>
         <file>bom.ini</file>
+        <file>withcomments.ini</file>
     </qresource>
 </RCC>

tests/auto/corelib/io/qsettings/tst_qsettings.cpp

@@ -187,6 +187,7 @@ private slots:
     void bom();
     void embeddedZeroByte_data();
     void embeddedZeroByte();
+    void spaceAfterComment();
 
     void testXdg();
 private:
@@ -764,6 +765,34 @@ void tst_QSettings::embeddedZeroByte()
     }
 }
 
+void tst_QSettings::spaceAfterComment()
+{
+    QSettings settings(QFINDTESTDATA("withcomments.ini"), QSettings::IniFormat);
+    QCOMPARE(settings.status(), QSettings::NoError);
+
+    QStringList groups = settings.childGroups();
+    QVERIFY(groups.contains("Regular"));
+    QVERIFY(groups.contains("WithSpaces"));
+    QVERIFY(groups.contains("WithTab"));
+    QVERIFY(groups.contains("SpacedGroup"));
+
+    settings.beginGroup("Regular");
+    QCOMPARE(settings.value("bar"), QVariant(2));
+    settings.endGroup();
+
+    settings.beginGroup("WithSpaces");
+    QCOMPARE(settings.value("bar"), QVariant(4));
+    settings.endGroup();
+
+    settings.beginGroup("WithTab");
+    QCOMPARE(settings.value("bar"), QVariant(6));
+    settings.endGroup();
+
+    settings.beginGroup("SpacedGroup");
+    QCOMPARE(settings.value("bar"), QVariant(7));
+    settings.endGroup();
+}
+
 void tst_QSettings::testErrorHandling_data()
 {
     QTest::addColumn<int>("filePerms"); // -1 means file should not exist

tests/auto/corelib/io/qsettings/withcomments.ini

@@ -0,0 +1,19 @@
+; -*- conf -*-
+; If you edit this file, make sure, that "WithSpaces" has spaces and that
+; "WithTab" has one tab
+
+[Regular]
+;bar = 1
+bar = 2
+
+[WithSpaces]
+;bar = 3
+        bar = 4
+
+[WithTab]
+;bar = 5
+	bar = 6
+
+; [SpacedGroup]
+    [SpacedGroup]
+    bar = 7