Allow QQmlComponent::loadUrl() to load absolute URLs with relative paths

Currently, QQmlTypeLoader::getType() will assert if passed a relative
URL, because it needs absolute URLs in order to ensure that it can use
them as keys for its cache. After dc6b73390 was merged, URLs like
QUrl::fromLocalFile("main.qml") (which are currently used in examples
of how to load a QQmlComponent) started causing the assertion to fail.

As mentioned in the comments of the bug report, some patches have
already been applied to QQmlComponent's QString-based constructors,
but both the constructors taking a QUrl and loadUrl() itself need
fixing.

This patch puts the fix into loadUrl() (the constructors call this
function) so that every operation
involving URLs is successful when using the documented methods.

Task-number: QTBUG-58837
Change-Id: Ib54ca52eddce6e7781cf96015f4c15af604233d3
Reviewed-by: David Faure <david.faure@kdab.com>

6 files changed, 109 insertions, 13 deletions

diff --git a/src/qml/doc/src/includes/qqmlcomponent.qdoc b/src/qml/doc/src/includes/qqmlcomponent.qdoc
new file mode 100644
index 0000000000..0eb60ed743
--- /dev/null
+++ b/src/qml/doc/src/includes/qqmlcomponent.qdoc
@@ -0,0 +1,58 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the documentation of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** 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 https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** BSD License Usage
+** Alternatively, you may use this file under the terms of the BSD license
+** as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of The Qt Company Ltd nor the names of its
+**     contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+//! [url-note]
+Ensure that the URL provided is full and correct, in particular, use
+\l QUrl::fromLocalFile() when loading a file from the local filesystem.
+
+Relative paths will be resolved against the engine's
+\l {QQmlEngine::baseUrl}{baseUrl()}, which is the current working directory
+unless specified.
+//! [url-note]
diff --git a/src/qml/qml/qqmlcomponent.cpp b/src/qml/qml/qqmlcomponent.cpp
index e872b1d92e..4da6b7958c 100644
--- a/src/qml/qml/qqmlcomponent.cpp
+++ b/src/qml/qml/qqmlcomponent.cpp
@@ -496,8 +496,7 @@ QQmlComponent::QQmlComponent(QQmlEngine *engine, QObject *parent)
     Create a QQmlComponent from the given \a url and give it the
     specified \a parent and \a engine.
 
-    Ensure that the URL provided is full and correct, in particular, use
-    \l QUrl::fromLocalFile() when loading a file from the local filesystem.
+    \include qqmlcomponent.qdoc url-note
 
     \sa loadUrl()
 */
@@ -511,8 +510,7 @@ QQmlComponent::QQmlComponent(QQmlEngine *engine, const QUrl &url, QObject *paren
     specified \a parent and \a engine. If \a mode is \l Asynchronous,
     the component will be loaded and compiled asynchronously.
 
-    Ensure that the URL provided is full and correct, in particular, use
-    \l QUrl::fromLocalFile() when loading a file from the local filesystem.
+    \include qqmlcomponent.qdoc url-note
 
     \sa loadUrl()
 */
@@ -548,7 +546,7 @@ QQmlComponent::QQmlComponent(QQmlEngine *engine, const QString &fileName,
     : QQmlComponent(engine, parent)
 {
     Q_D(QQmlComponent);
-    const QUrl url = QDir::isAbsolutePath(fileName) ? QUrl::fromLocalFile(fileName) : d->engine->baseUrl().resolved(QUrl(fileName));
+    const QUrl url = QDir::isAbsolutePath(fileName) ? QUrl::fromLocalFile(fileName) : QUrl(fileName);
     d->loadUrl(url, mode);
 }
 
@@ -608,8 +606,7 @@ QQmlContext *QQmlComponent::creationContext() const
 /*!
     Load the QQmlComponent from the provided \a url.
 
-    Ensure that the URL provided is full and correct, in particular, use
-    \l QUrl::fromLocalFile() when loading a file from the local filesystem.
+    \include qqmlcomponent.qdoc url-note
 */
 void QQmlComponent::loadUrl(const QUrl &url)
 {
@@ -621,8 +618,7 @@ void QQmlComponent::loadUrl(const QUrl &url)
     Load the QQmlComponent from the provided \a url.
     If \a mode is \l Asynchronous, the component will be loaded and compiled asynchronously.
 
-    Ensure that the URL provided is full and correct, in particular, use
-    \l QUrl::fromLocalFile() when loading a file from the local filesystem.
+    \include qqmlcomponent.qdoc url-note
 */
 void QQmlComponent::loadUrl(const QUrl &url, QQmlComponent::CompilationMode mode)
 {
@@ -635,11 +631,21 @@ void QQmlComponentPrivate::loadUrl(const QUrl &newUrl, QQmlComponent::Compilatio
     Q_Q(QQmlComponent);
     clear();
 
-    if ((newUrl.isRelative() && !newUrl.isEmpty())
-    || newUrl.scheme() == QLatin1String("file")) // Workaround QTBUG-11929
-        url = engine->baseUrl().resolved(newUrl);
-    else
+    if (newUrl.isRelative()) {
+        // The new URL is a relative URL like QUrl("main.qml").
+        url = engine->baseUrl().resolved(QUrl(newUrl.toString()));
+    } else if (engine->baseUrl().isLocalFile() && newUrl.isLocalFile() && !QDir::isAbsolutePath(newUrl.toLocalFile())) {
+        // The new URL is a file on disk but it's a relative path; e.g.:
+        // QUrl::fromLocalFile("main.qml") or QUrl("file:main.qml")
+        // We need to remove the scheme so that it becomes a relative URL with a relative path:
+        QUrl fixedUrl(newUrl);
+        fixedUrl.setScheme(QString());
+        // Then, turn it into an absolute URL with an absolute path by resolving it against the engine's baseUrl().
+        // This is a compatibility hack for QTBUG-58837.
+        url = engine->baseUrl().resolved(fixedUrl);
+    } else {
         url = newUrl;
+    }
 
     if (newUrl.isEmpty()) {
         QQmlError error;
diff --git a/tests/auto/qml/qqmlcomponent/data/QtObjectComponent#2.qml b/tests/auto/qml/qqmlcomponent/data/QtObjectComponent#2.qml
new file mode 100644
index 0000000000..431c659424
--- /dev/null
+++ b/tests/auto/qml/qqmlcomponent/data/QtObjectComponent#2.qml
@@ -0,0 +1,3 @@
+import QtQml 2.0
+
+QtObject {}
diff --git a/tests/auto/qml/qqmlcomponent/data/QtObjectComponent.qml b/tests/auto/qml/qqmlcomponent/data/QtObjectComponent.qml
new file mode 100644
index 0000000000..431c659424
--- /dev/null
+++ b/tests/auto/qml/qqmlcomponent/data/QtObjectComponent.qml
@@ -0,0 +1,3 @@
+import QtQml 2.0
+
+QtObject {}
diff --git a/tests/auto/qml/qqmlcomponent/qqmlcomponent.pro b/tests/auto/qml/qqmlcomponent/qqmlcomponent.pro
index 9f8c8a4e24..0d501ebefd 100644
--- a/tests/auto/qml/qqmlcomponent/qqmlcomponent.pro
+++ b/tests/auto/qml/qqmlcomponent/qqmlcomponent.pro
@@ -8,6 +8,8 @@ SOURCES += tst_qqmlcomponent.cpp \
 
 HEADERS += ../../shared/testhttpserver.h
 
+RESOURCES += data/QtObjectComponent.qml
+
 include (../../shared/util.pri)
 
 TESTDATA = data/*
diff --git a/tests/auto/qml/qqmlcomponent/tst_qqmlcomponent.cpp b/tests/auto/qml/qqmlcomponent/tst_qqmlcomponent.cpp
index f2b0b9973e..3c78f6601e 100644
--- a/tests/auto/qml/qqmlcomponent/tst_qqmlcomponent.cpp
+++ b/tests/auto/qml/qqmlcomponent/tst_qqmlcomponent.cpp
@@ -117,6 +117,8 @@ private slots:
     void recursion();
     void recursionContinuation();
     void callingContextForInitialProperties();
+    void relativeUrl_data();
+    void relativeUrl();
 
 private:
     QQmlEngine engine;
@@ -581,6 +583,28 @@ void tst_qqmlcomponent::callingContextForInitialProperties()
     QVERIFY(checker->scopeObject->metaObject()->indexOfProperty("incubatedObject") != -1);
 }
 
+void tst_qqmlcomponent::relativeUrl_data()
+{
+    QTest::addColumn<QUrl>("url");
+
+    QTest::addRow("fromLocalFile") << QUrl::fromLocalFile("data/QtObjectComponent.qml");
+    QTest::addRow("fromLocalFileHash") << QUrl::fromLocalFile("data/QtObjectComponent#2.qml");
+    QTest::addRow("constructor") << QUrl("data/QtObjectComponent.qml");
+    QTest::addRow("absolute") << QUrl::fromLocalFile(QFINDTESTDATA("data/QtObjectComponent.qml"));
+    QTest::addRow("qrc") << QUrl("qrc:/data/QtObjectComponent.qml");
+}
+
+void tst_qqmlcomponent::relativeUrl()
+{
+    QFETCH(QUrl, url);
+
+    QQmlComponent component(&engine);
+    // Shouldn't assert in QQmlTypeLoader; we want QQmlComponent to assume that
+    // data/QtObjectComponent.qml refers to the data/QtObjectComponent.qml in the current working directory.
+    component.loadUrl(url);
+    QVERIFY2(!component.isError(), qPrintable(component.errorString()));
+}
+
 QTEST_MAIN(tst_qqmlcomponent)
 
 #include "tst_qqmlcomponent.moc"