Fix potential crash in project setup.

If we
    - held an existing project open (in an IDE) and
    - changed its build directory and
    - a second qbs instance also held a project open there and
    - that second qbs instance used the same profile
then we would correctly detect that a competing build graph was already
present, but afterwards we would erroneously delete the build graph lock
object of the existing project, leading to a double-delete later when
the project itself was deleted.

Task-number: QTCREATORBUG-16376
Change-Id: Ie6c621f1dab5cc7b7ff97bf6c25d62609dc9eb35
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

1 files changed, 4 insertions, 1 deletions

diff --git a/src/lib/corelib/api/internaljobs.cpp b/src/lib/corelib/api/internaljobs.cpp
index 2c0693566..87ae69617 100644
--- a/src/lib/corelib/api/internaljobs.cpp
+++ b/src/lib/corelib/api/internaljobs.cpp
@@ -226,6 +226,7 @@ TopLevelProjectPtr InternalSetupProjectJob::project() const
 
 void InternalSetupProjectJob::start()
 {
+    const TopLevelProjectConstPtr existingProject = m_existingProject;
     BuildGraphLocker *bgLocker = m_existingProject ? m_existingProject->bgLocker : 0;
     try {
         const ErrorInfo err = m_parameters.expandBuildConfiguration();
@@ -249,7 +250,9 @@ void InternalSetupProjectJob::start()
     } catch (const ErrorInfo &error) {
         m_newProject.clear();
         setError(error);
-        if (!m_existingProject)
+
+        // Delete the build graph locker if and only if we allocated it here.
+        if (!existingProject)
             delete bgLocker;
     }
     emit finished(this);