Fix dependency tracking when using --check-timestamps

The --check-timestamps option is meant to be used to reconstruct a build
after accidentally removing the build graph file. This means we must re-
scan sources even though they appear up to date, in order to reconstruct
e.g. dependencies between C++ sources and headers.

Task-number: QBS-1178
Change-Id: I19ac385e57ceb7fcbba2df1ef24497935c067512
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

7 files changed, 39 insertions, 1 deletions

diff --git a/src/lib/corelib/buildgraph/executor.cpp b/src/lib/corelib/buildgraph/executor.cpp
index 786fdbc42..dc81385e2 100644
--- a/src/lib/corelib/buildgraph/executor.cpp
+++ b/src/lib/corelib/buildgraph/executor.cpp
@@ -906,7 +906,8 @@ void Executor::potentiallyRunTransformer(const TransformerPtr &transformer)
         return;
     }
 
-    if (!mustExecuteTransformer(transformer)) {
+    const bool mustExecute = mustExecuteTransformer(transformer);
+    if (!mustExecute && !m_buildOptions.forceTimestampCheck()) {
         if (m_doDebug)
             m_logger.qbsDebug() << "[EXEC] Up to date. Skipping.";
         finishTransformer(transformer);
@@ -925,6 +926,13 @@ void Executor::potentiallyRunTransformer(const TransformerPtr &transformer)
             return;
     }
 
+    if (!mustExecute) {
+        if (m_doDebug)
+            m_logger.qbsDebug() << "[EXEC] Up to date. Skipping.";
+        finishTransformer(transformer);
+        return;
+    }
+
     if (m_buildOptions.executeRulesOnly())
         finishTransformer(transformer);
     else
diff --git a/tests/auto/blackbox/testdata/check-timestamps/check-timestamps.qbs b/tests/auto/blackbox/testdata/check-timestamps/check-timestamps.qbs
new file mode 100644
index 000000000..32456444c
--- /dev/null
+++ b/tests/auto/blackbox/testdata/check-timestamps/check-timestamps.qbs
@@ -0,0 +1,10 @@
+import qbs
+
+CppApplication {
+    name: "app"
+    files: [
+        "file.cpp",
+        "file.h",
+        "main.cpp",
+    ]
+}
diff --git a/tests/auto/blackbox/testdata/check-timestamps/file.cpp b/tests/auto/blackbox/testdata/check-timestamps/file.cpp
new file mode 100644
index 000000000..4752b89d5
--- /dev/null
+++ b/tests/auto/blackbox/testdata/check-timestamps/file.cpp
@@ -0,0 +1,3 @@
+#include "file.h"
+
+void f() { }
diff --git a/tests/auto/blackbox/testdata/check-timestamps/file.h b/tests/auto/blackbox/testdata/check-timestamps/file.h
new file mode 100644
index 000000000..789447c02
--- /dev/null
+++ b/tests/auto/blackbox/testdata/check-timestamps/file.h
@@ -0,0 +1 @@
+void f();
diff --git a/tests/auto/blackbox/testdata/check-timestamps/main.cpp b/tests/auto/blackbox/testdata/check-timestamps/main.cpp
new file mode 100644
index 000000000..237c8ce18
--- /dev/null
+++ b/tests/auto/blackbox/testdata/check-timestamps/main.cpp
@@ -0,0 +1 @@
+int main() {}
diff --git a/tests/auto/blackbox/tst_blackbox.cpp b/tests/auto/blackbox/tst_blackbox.cpp
index 6aa0fed2f..176f20816 100644
--- a/tests/auto/blackbox/tst_blackbox.cpp
+++ b/tests/auto/blackbox/tst_blackbox.cpp
@@ -4040,6 +4040,20 @@ void TestBlackbox::checkProjectFilePath()
     QVERIFY2(m_qbsStdout.contains("main2.cpp"), m_qbsStdout.constData());
 }
 
+void TestBlackbox::checkTimestamps()
+{
+    QDir::setCurrent(testDataDir + "/check-timestamps");
+    QCOMPARE(runQbs(), 0);
+    QVERIFY2(m_qbsStdout.contains("compiling file.cpp"), m_qbsStdout.constData());
+    QVERIFY2(m_qbsStdout.contains("compiling main.cpp"), m_qbsStdout.constData());
+    QVERIFY(QFile::remove(relativeBuildGraphFilePath()));
+    WAIT_FOR_NEW_TIMESTAMP();
+    touch("file.h");
+    QCOMPARE(runQbs(QStringList("--check-timestamps")), 0);
+    QVERIFY2(m_qbsStdout.contains("compiling file.cpp"), m_qbsStdout.constData());
+    QVERIFY2(!m_qbsStdout.contains("compiling main.cpp"), m_qbsStdout.constData());
+}
+
 class TemporaryDefaultProfileRemover
 {
 public:
diff --git a/tests/auto/blackbox/tst_blackbox.h b/tests/auto/blackbox/tst_blackbox.h
index 2f620017a..a56ac2e19 100644
--- a/tests/auto/blackbox/tst_blackbox.h
+++ b/tests/auto/blackbox/tst_blackbox.h
@@ -54,6 +54,7 @@ private slots:
     void changeInImportedFile();
     void changeTrackingAndMultiplexing();
     void checkProjectFilePath();
+    void checkTimestamps();
     void clean();
     void cli();
     void combinedSources();