qmake: require a drive in a DOS path for it to be absolute

For Q_OS_WIN, a path is only truly absolute if it includes a drive
letter; merely starting with a slash is not enough.  (We can't support
UNC paths, so don't even try: qmake runs various commands in the
source directory using CMD.exe, which doesn't support UNC as PWD.)
This requires, when resolving a path relative to a root, transcribing
the root's drive to such not-quite-absolute paths.

Changed QMakeGlobals, $$absolute_path() and $$relative_path() to now
use IoUtils::resolvePath() rather than delegating to QDir's absolute
path method, since that doesn't correctly recognize the need for a
drive letter (and qmake did run into problems with some paths, from
splitPathList and a failing test, as a result).

Moved existing ioUtils tests for handling of relative / absolute paths
out into separate functions and expanded significantly.  Fixed some
existing tests to use an absolute path where one is needed; added two
tests involving driveless (but rooted) paths; and fixed the test init
to set a value for QT_HOST_DATA/src property (the lack of which lead
to an assertion failure with this fix).

Task-number: QTBUG-50839
Change-Id: I2bfc13c1bfbe1ae09997274622ea55cb3de31b43
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>

1 files changed, 15 insertions, 8 deletions

diff --git a/qmake/library/ioutils.cpp b/qmake/library/ioutils.cpp
index 684bcb9a37..afd41912fe 100644
--- a/qmake/library/ioutils.cpp
+++ b/qmake/library/ioutils.cpp
@@ -66,21 +66,22 @@ IoUtils::FileType IoUtils::fileType(const QString &fileName)
 
 bool IoUtils::isRelativePath(const QString &path)
 {
-    if (path.startsWith(QLatin1Char('/')))
-        return false;
 #ifdef QMAKE_BUILTIN_PRFS
     if (path.startsWith(QLatin1String(":/")))
         return false;
 #endif
 #ifdef Q_OS_WIN
-    if (path.startsWith(QLatin1Char('\\')))
-        return false;
-    // Unlike QFileInfo, this won't accept a relative path with a drive letter.
-    // Such paths result in a royal mess anyway ...
+    // Unlike QFileInfo, this considers only paths with both a drive prefix and
+    // a subsequent (back-)slash absolute:
     if (path.length() >= 3 && path.at(1) == QLatin1Char(':') && path.at(0).isLetter()
-        && (path.at(2) == QLatin1Char('/') || path.at(2) == QLatin1Char('\\')))
+        && (path.at(2) == QLatin1Char('/') || path.at(2) == QLatin1Char('\\'))) {
         return false;
-#endif
+    }
+    // (... unless, of course, they're UNC, which qmake fails on anyway)
+#else
+    if (path.startsWith(QLatin1Char('/')))
+        return false;
+#endif // Q_OS_WIN
     return true;
 }
 
@@ -100,6 +101,12 @@ QString IoUtils::resolvePath(const QString &baseDir, const QString &fileName)
         return QString();
     if (isAbsolutePath(fileName))
         return QDir::cleanPath(fileName);
+#ifdef Q_OS_WIN // Add drive to otherwise-absolute path:
+    if (fileName.at(0).unicode() == '/' || fileName.at(0).unicode() == '\\') {
+        Q_ASSERT(isAbsolutePath(baseDir));
+        return QDir::cleanPath(baseDir.left(2) + fileName);
+    }
+#endif // Q_OS_WIN
     return QDir::cleanPath(baseDir + QLatin1Char('/') + fileName);
 }