make QProcessEnvironment on Windows preserve variable name case

while windows itself does not care which case the variable names are in,
they may be passed to unix tools which *do* care.

note that this uses true case folding for string comparisons while
windows uses uppercasing. this means that "ess" and "eß" will be
considered the same by us, while not by windows. this is not expected to
have real-world impact, particularly because non-ascii variable names
are not used much.

Task-number: QTCREATORBUG-3110
Reviewed-by: thiago
Reviewed-by: dt
(cherry picked from commit f3db5603871928ebed43a085a496397e65952b39)

src/corelib/io/qprocess.cpp

@@ -145,7 +145,7 @@ QT_BEGIN_NAMESPACE
 */
 #ifdef Q_OS_WIN
 static inline QProcessEnvironmentPrivate::Key prepareName(const QString &name)
-{ return name.toUpper(); }
+{ return QProcessEnvironmentPrivate::Key(name); }
 static inline QString nameToString(const QProcessEnvironmentPrivate::Key &name)
 { return name; }
 static inline QProcessEnvironmentPrivate::Value prepareValue(const QString &value)

src/corelib/io/qprocess_p.h

@@ -85,7 +85,15 @@ class QProcessEnvironmentPrivate: public QSharedData
 {
 public:
 #ifdef Q_OS_WIN
-    typedef QString Key;
+    class Key : public QString
+    {
+    public:
+        Key() {}
+        explicit Key(const QString &other) : QString(other) {}
+        Key(const Key &other) : QString(other) {}
+        bool operator==(const Key &other) const { return !compare(other, Qt::CaseInsensitive); }
+    };
+
     typedef QString Value;
 #else
     typedef QByteArray Key;
@@ -100,6 +108,10 @@ public:
     QStringList keys() const;
     void insert(const Hash &hash);
 };
+#ifdef Q_OS_WIN
+Q_DECLARE_TYPEINFO(QProcessEnvironmentPrivate::Key, Q_MOVABLE_TYPE);
+inline uint qHash(const QProcessEnvironmentPrivate::Key &key) { return qHash(key.toCaseFolded()); }
+#endif
 
 class QProcessPrivate : public QIODevicePrivate
 {

src/corelib/io/qprocess_win.cpp

@@ -285,17 +285,19 @@ static QByteArray qt_create_environment(const QProcessEnvironmentPrivate::Hash &
         QProcessEnvironmentPrivate::Hash copy = environment;
 
         // add PATH if necessary (for DLL loading)
-        if (!copy.contains(QLatin1String("PATH"))) {
+        QProcessEnvironmentPrivate::Key pathKey(QLatin1String("PATH"));
+        if (!copy.contains(pathKey)) {
             QByteArray path = qgetenv("PATH");
             if (!path.isEmpty())
-                copy.insert(QLatin1String("PATH"), QString::fromLocal8Bit(path));
+                copy.insert(pathKey, QString::fromLocal8Bit(path));
         }
 
         // add systemroot if needed
-        if (!copy.contains(QLatin1String("SYSTEMROOT"))) {
-            QByteArray systemRoot = qgetenv("SYSTEMROOT");
+        QProcessEnvironmentPrivate::Key rootKey(QLatin1String("SystemRoot"));
+        if (!copy.contains(rootKey)) {
+            QByteArray systemRoot = qgetenv("SystemRoot");
             if (!systemRoot.isEmpty())
-                copy.insert(QLatin1String("SYSTEMROOT"), QString::fromLocal8Bit(systemRoot));
+                copy.insert(rootKey, QString::fromLocal8Bit(systemRoot));
         }
 
         int pos = 0;

tests/auto/qprocessenvironment/tst_qprocessenvironment.cpp

@@ -43,10 +43,6 @@
 #include <QObject>
 #include <QProcessEnvironment>
 
-// Note:
-// in cross-platform tests, ALWAYS use UPPERCASE variable names
-// That's because on Windows, the variables are uppercased
-
 class tst_QProcessEnvironment: public QObject
 {
     Q_OBJECT
@@ -214,7 +210,7 @@ void tst_QProcessEnvironment::caseSensitivity()
     e.insert("foo", "bar");
 
 #ifdef Q_OS_WIN
-    // on Windows, it's uppercased
+    // Windows is case-insensitive, but case-preserving
     QVERIFY(e.contains("foo"));
     QVERIFY(e.contains("FOO"));
     QVERIFY(e.contains("FoO"));
@@ -223,8 +219,12 @@ void tst_QProcessEnvironment::caseSensitivity()
     QCOMPARE(e.value("FOO"), QString("bar"));
     QCOMPARE(e.value("FoO"), QString("bar"));
 
+    // Per Windows, this overwrites the value, but keeps the name's original capitalization
+    e.insert("Foo", "Bar");
+
     QStringList list = e.toStringList();
-    QCOMPARE(list.at(0), QString("FOO=bar"));
+    QCOMPARE(list.length(), 1);
+    QCOMPARE(list.at(0), QString("foo=Bar"));
 #else
     // otherwise, it's case sensitive
     QVERIFY(e.contains("foo"));
@@ -236,6 +236,7 @@ void tst_QProcessEnvironment::caseSensitivity()
     QCOMPARE(e.value("foo"), QString("bar"));
 
     QStringList list = e.toStringList();
+    QCOMPARE(list.length(), 2);
     QVERIFY(list.contains("foo=bar"));
     QVERIFY(list.contains("FOO=baz"));
 #endif