QbsProjectManager: Fix crash when unloading a building project

Note that unloading a building project is generally broken in that the
build manager waits indefinitely for the build step's finished() signal,
but that's a general problem which needs to get addressed in a different
patch. This one fixes a qbs-specific crash.

Fixes: QTCREATORBUG-23851
Change-Id: I93e254acd1c73fe7495d01fcad04ea9301130dd0
Reviewed-by: Ivan Komissarov <ABBAPOH@gmail.com>
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/qbsprojectmanager/qbsbuildconfiguration.cpp

@@ -159,6 +159,14 @@ QbsBuildConfiguration::QbsBuildConfiguration(Target *target, Core::Id id)
 
 QbsBuildConfiguration::~QbsBuildConfiguration()
 {
+    for (BuildStep * const bs : buildSteps()->steps()) {
+        if (const auto qbs = qobject_cast<QbsBuildStep *>(bs))
+            qbs->dropSession();
+    }
+    for (BuildStep * const cs : cleanSteps()->steps()) {
+        if (const auto qcs = qobject_cast<QbsCleanStep *>(cs))
+            qcs->dropSession();
+    }
     delete m_buildSystem;
 }
 

src/plugins/qbsprojectmanager/qbsbuildstep.cpp

@@ -539,6 +539,15 @@ QbsBuildStepData QbsBuildStep::stepData() const
     return data;
 }
 
+void QbsBuildStep::dropSession()
+{
+    if (m_session) {
+        doCancel();
+        m_session->disconnect(this);
+        m_session = nullptr;
+    }
+}
+
 
 // --------------------------------------------------------------------
 // QbsBuildStepConfigWidget:

src/plugins/qbsprojectmanager/qbsbuildstep.h

@@ -72,6 +72,8 @@ public:
     QbsBuildSystem *qbsBuildSystem() const;
     QbsBuildStepData stepData() const;
 
+    void dropSession();
+
 signals:
     void qbsConfigurationChanged();
     void qbsBuildOptionsChanged();

src/plugins/qbsprojectmanager/qbscleanstep.cpp

@@ -85,6 +85,15 @@ QbsCleanStep::~QbsCleanStep()
         m_session->disconnect(this);
 }
 
+void QbsCleanStep::dropSession()
+{
+    if (m_session) {
+        doCancel();
+        m_session->disconnect(this);
+        m_session = nullptr;
+    }
+}
+
 bool QbsCleanStep::init()
 {
     if (buildSystem()->isParsing() || m_session)

src/plugins/qbsprojectmanager/qbscleanstep.h

@@ -46,6 +46,8 @@ public:
 
     QbsBuildStepData stepData() const;
 
+    void dropSession();
+
 private:
     bool init() override;
     void doRun() override;