Merge fixes for QDir::operator==

There were two fixes in 4.8 which each fixed a part of the problem.
Comparing canonical paths is more correct, but is only possible where
both directories exist. If neither directory exists, then compare
absolute paths instead.
Changed a regression test, because /tmp is a symbolic link on MacOS.
I.E. "/tmp/.." is canonically "/private" and not "/" as expected.

Task-Number: QTBUG-20495
Reviewed-By: joao

2 files changed, 34 insertions, 3 deletions

diff --git a/src/corelib/io/qdir.cpp b/src/corelib/io/qdir.cpp
index 3271148..9081e31 100644
--- a/src/corelib/io/qdir.cpp
+++ b/src/corelib/io/qdir.cpp
@@ -1638,8 +1638,19 @@ bool QDir::operator==(const QDir &dir) const
         if (d->dirEntry.filePath() == other->dirEntry.filePath())
             return true;
 
-        // Fallback to expensive canonical path computation
-        return canonicalPath().compare(dir.canonicalPath(), sensitive) == 0;
+        if (exists()) {
+            if (!dir.exists())
+                return false; //can't be equal if only one exists
+            // Both exist, fallback to expensive canonical path computation
+            return canonicalPath().compare(dir.canonicalPath(), sensitive) == 0;
+        } else {
+            if (dir.exists())
+                return false; //can't be equal if only one exists
+            // Neither exists, compare absolute paths rather than canonical (which would be empty strings)
+            d->resolveAbsoluteEntry();
+            other->resolveAbsoluteEntry();
+            return d->absoluteDirEntry.filePath().compare(other->absoluteDirEntry.filePath(), sensitive) == 0;
+        }
     }
     return false;
 }
diff --git a/tests/auto/qdir/tst_qdir.cpp b/tests/auto/qdir/tst_qdir.cpp
index 7e5ec79..9693480 100644
--- a/tests/auto/qdir/tst_qdir.cpp
+++ b/tests/auto/qdir/tst_qdir.cpp
@@ -1951,10 +1951,30 @@ void tst_QDir::equalityOperator_data()
         << "." << "*.cpp" << int(QDir::Name) << int(QDir::Files)
         << true;
 
-    QTest::newRow("QTBUG-20495-root") << QDir::rootPath() + "tmp/.." << "*.cpp" << int(QDir::Name) << int(QDir::Files)
+    //need a path in the root directory that is unlikely to be a symbolic link.
+#if defined (Q_OS_WIN)
+    QString pathinroot("c:/windows/..");
+#elif defined (Q_OS_SYMBIAN)
+    QString pathinroot("c:/data/..");
+#else
+    QString pathinroot("/sbin/..");
+#endif
+    QTest::newRow("QTBUG-20495-root") << pathinroot << "*.cpp" << int(QDir::Name) << int(QDir::Files)
+        << QDir::rootPath() << "*.cpp" << int(QDir::Name) << int(QDir::Files)
+        << true;
+
+    QTest::newRow("slashdot") << QDir::rootPath() + "." << "*.cpp" << int(QDir::Name) << int(QDir::Files)
         << QDir::rootPath() << "*.cpp" << int(QDir::Name) << int(QDir::Files)
         << true;
 
+    QTest::newRow("slashdotslash") << QDir::rootPath() + "./" << "*.cpp" << int(QDir::Name) << int(QDir::Files)
+        << QDir::rootPath() << "*.cpp" << int(QDir::Name) << int(QDir::Files)
+        << true;
+
+    QTest::newRow("nonexistantpaths") << "dir-that-dont-exist" << "*.cpp" << int(QDir::Name) << int(QDir::Files)
+        << "another-dir-that-dont-exist" << "*.cpp" << int(QDir::Name) << int(QDir::Files)
+        << false;
+
     QTest::newRow("diff-filters") << SRCDIR << "*.cpp" << int(QDir::Name) << int(QDir::Files)
         << SRCDIR << "*.cpp" << int(QDir::Name) << int(QDir::Dirs)
         << false;