ProjectExplorer: cancel MSVC tool chain detection on shutdown

Task-number: QTCREATORBUG-21329
Change-Id: I681757f1a2e77ecd7f766f25ab554d57473f1c6d
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/projectexplorer/msvctoolchain.cpp

@@ -1184,6 +1184,11 @@ bool MsvcToolChain::operator ==(const ToolChain &other) const
     return m_varsBatArg == msvcTc->m_varsBatArg;
 }
 
+void MsvcToolChain::cancelMsvcToolChainDetection()
+{
+    envModThreadPool()->clear();
+}
+
 bool MsvcToolChainFactory::canRestore(const QVariantMap &data)
 {
     const Core::Id id = typeIdFromMap(data);

src/plugins/projectexplorer/msvctoolchain.h

@@ -79,6 +79,8 @@ public:
 
     bool operator == (const ToolChain &) const override;
 
+    static void cancelMsvcToolChainDetection();
+
 protected:
     explicit MsvcToolChain(Core::Id typeId, const QString &name, const Abi &abi,
                            const QString &varsBat, const QString &varsBatArg,

src/plugins/projectexplorer/projectexplorer.cpp

@@ -1657,6 +1657,7 @@ ExtensionSystem::IPlugin::ShutdownFlag ProjectExplorerPlugin::aboutToShutdown()
     disconnect(ModeManager::instance(), &ModeManager::currentModeChanged,
                dd, &ProjectExplorerPluginPrivate::currentModeChanged);
     ProjectTree::aboutToShutDown();
+    ToolChainManager::aboutToShutdown();
     SessionManager::closeAllProjects();
 
     dd->m_shuttingDown = true;

src/plugins/projectexplorer/toolchainmanager.cpp

@@ -27,6 +27,7 @@
 
 #include "abi.h"
 #include "kitinformation.h"
+#include "msvctoolchain.h"
 #include "toolchain.h"
 #include "toolchainsettingsaccessor.h"
 
@@ -248,4 +249,9 @@ bool ToolChainManager::isLanguageSupported(const Core::Id &id)
     return Utils::contains(d->m_languages, Utils::equal(&LanguageDisplayPair::id, id));
 }
 
+void ToolChainManager::aboutToShutdown()
+{
+    MsvcToolChain::cancelMsvcToolChainDetection();
+}
+
 } // namespace ProjectExplorer

src/plugins/projectexplorer/toolchainmanager.h

@@ -74,6 +74,8 @@ public:
     static QString displayNameOfLanguageId(const Core::Id &id);
     static bool isLanguageSupported(const Core::Id &id);
 
+    static void aboutToShutdown();
+
     void saveToolChains();
 
 signals: