Fix edge case in change tracking

Under certain circumstances, transformers could lose the information
about properties requested by their commands. Make sure this doesn't
happen anymore.

Change-Id: Ib224cd8425760543ae805875024e7886f67825fe
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

8 files changed, 60 insertions, 0 deletions

diff --git a/src/lib/corelib/buildgraph/rulesapplicator.cpp b/src/lib/corelib/buildgraph/rulesapplicator.cpp
index 51b743527..0df7d204d 100644
--- a/src/lib/corelib/buildgraph/rulesapplicator.cpp
+++ b/src/lib/corelib/buildgraph/rulesapplicator.cpp
@@ -358,6 +358,7 @@ Artifact *RulesApplicator::createOutputArtifact(const QString &filePath, const F
         if (m_rule->declaresInputs() && m_rule->requiresInputs)
             outputArtifact->clearTimestamp();
         m_invalidatedArtifacts += outputArtifact;
+        m_transformer->rescueChangeTrackingData(outputArtifact->transformer);
     } else {
         QScopedPointer<Artifact> newArtifact(new Artifact);
         newArtifact->artifactType = Artifact::Generated;
diff --git a/src/lib/corelib/buildgraph/transformer.cpp b/src/lib/corelib/buildgraph/transformer.cpp
index 0e5b4a084..b6e02e708 100644
--- a/src/lib/corelib/buildgraph/transformer.cpp
+++ b/src/lib/corelib/buildgraph/transformer.cpp
@@ -260,6 +260,17 @@ void Transformer::createCommands(ScriptEngine *engine, const ScriptFunctionConst
     }
 }
 
+void Transformer::rescueChangeTrackingData(const TransformerConstPtr &other)
+{
+    if (!other)
+        return;
+    propertiesRequestedInPrepareScript = other->propertiesRequestedInPrepareScript;
+    propertiesRequestedInCommands = other->propertiesRequestedInCommands;
+    propertiesRequestedFromArtifactInPrepareScript
+            = other->propertiesRequestedFromArtifactInPrepareScript;
+    propertiesRequestedFromArtifactInCommands = other->propertiesRequestedFromArtifactInCommands;
+}
+
 void Transformer::load(PersistentPool &pool)
 {
     pool.load(rule);
diff --git a/src/lib/corelib/buildgraph/transformer.h b/src/lib/corelib/buildgraph/transformer.h
index e4ffcb83b..b83321bda 100644
--- a/src/lib/corelib/buildgraph/transformer.h
+++ b/src/lib/corelib/buildgraph/transformer.h
@@ -82,6 +82,7 @@ public:
     void setupExplicitlyDependsOn(QScriptValue targetScriptValue);
     void createCommands(ScriptEngine *engine, const ScriptFunctionConstPtr &script,
                         const QScriptValueList &args);
+    void rescueChangeTrackingData(const TransformerConstPtr &other);
 
 private:
     Transformer();
diff --git a/tests/auto/blackbox/testdata/rescue-transformer-data/main.cpp b/tests/auto/blackbox/testdata/rescue-transformer-data/main.cpp
new file mode 100644
index 000000000..237c8ce18
--- /dev/null
+++ b/tests/auto/blackbox/testdata/rescue-transformer-data/main.cpp
@@ -0,0 +1 @@
+int main() {}
diff --git a/tests/auto/blackbox/testdata/rescue-transformer-data/modules/m/m.qbs b/tests/auto/blackbox/testdata/rescue-transformer-data/modules/m/m.qbs
new file mode 100644
index 000000000..03fdf7a6b
--- /dev/null
+++ b/tests/auto/blackbox/testdata/rescue-transformer-data/modules/m/m.qbs
@@ -0,0 +1,21 @@
+import qbs
+
+Module {
+    property bool p
+
+    Rule {
+        multiplex: true
+        Artifact {
+            filePath: "dummy"
+            fileTags: ["out"]
+        }
+        prepare: {
+            var cmd = new JavaScriptCommand();
+            cmd.description = "creating dummy";
+            cmd.sourceCode = function() {
+                console.info("m.p: " + product.m.p);
+            };
+            return [cmd];
+        }
+    }
+}
diff --git a/tests/auto/blackbox/testdata/rescue-transformer-data/transformer-data-rescue.qbs b/tests/auto/blackbox/testdata/rescue-transformer-data/transformer-data-rescue.qbs
new file mode 100644
index 000000000..2eafcc01d
--- /dev/null
+++ b/tests/auto/blackbox/testdata/rescue-transformer-data/transformer-data-rescue.qbs
@@ -0,0 +1,7 @@
+import qbs
+
+CppApplication {
+    type: base.concat(["out"])
+    Depends { name: "m" }
+    files: ["main.cpp"]
+}
diff --git a/tests/auto/blackbox/tst_blackbox.cpp b/tests/auto/blackbox/tst_blackbox.cpp
index f26f33d53..3e6fe72b9 100644
--- a/tests/auto/blackbox/tst_blackbox.cpp
+++ b/tests/auto/blackbox/tst_blackbox.cpp
@@ -3258,6 +3258,23 @@ void TestBlackbox::requireDeprecated()
              m_qbsStderr.constData());
 }
 
+void TestBlackbox::rescueTransformerData()
+{
+    QDir::setCurrent(testDataDir + "/rescue-transformer-data");
+    QCOMPARE(runQbs(), 0);
+    QVERIFY2(m_qbsStdout.contains("compiling main.cpp") && m_qbsStdout.contains("m.p: undefined"),
+             m_qbsStdout.constData());
+    WAIT_FOR_NEW_TIMESTAMP();
+    touch("main.cpp");
+    QCOMPARE(runQbs(), 0);
+    QVERIFY2(m_qbsStdout.contains("compiling main.cpp") && !m_qbsStdout.contains("m.p: "),
+             m_qbsStdout.constData());
+    QCOMPARE(runQbs(QbsRunParameters("resolve", QStringList("modules.m.p:true"))), 0);
+    QCOMPARE(runQbs(), 0);
+    QVERIFY2(!m_qbsStdout.contains("compiling main.cpp") && m_qbsStdout.contains("m.p: true"),
+             m_qbsStdout.constData());
+}
+
 void TestBlackbox::multipleChanges()
 {
     QDir::setCurrent(testDataDir + "/multiple-changes");
diff --git a/tests/auto/blackbox/tst_blackbox.h b/tests/auto/blackbox/tst_blackbox.h
index 1426046cf..9b48fa40d 100644
--- a/tests/auto/blackbox/tst_blackbox.h
+++ b/tests/auto/blackbox/tst_blackbox.h
@@ -156,6 +156,7 @@ private slots:
     void reproducibleBuild_data();
     void require();
     void requireDeprecated();
+    void rescueTransformerData();
     void responseFiles();
     void ruleConditions();
     void ruleCycle();