diff --git a/src/plugins/android/androidtoolchain.cpp b/src/plugins/android/androidtoolchain.cpp
index 8894118436d..fa31889f83b 100644
--- a/src/plugins/android/androidtoolchain.cpp
+++ b/src/plugins/android/androidtoolchain.cpp
@@ -63,10 +63,11 @@ static const char ANDROID_NDK_TC_VERION[] = "Qt4ProjectManager.Android.NDK_TC_VE
 QHash<Abi, QList<int> > AndroidToolChainFactory::m_newestVersionForAbi;
 FileName AndroidToolChainFactory::m_ndkLocation;
 
-AndroidToolChain::AndroidToolChain(const Abi &abi, const QString &ndkToolChainVersion, Detection d)
+AndroidToolChain::AndroidToolChain(const Abi &abi, const QString &ndkToolChainVersion, Language l, Detection d)
     : GccToolChain(Constants::ANDROID_TOOLCHAIN_ID, d),
       m_ndkToolChainVersion(ndkToolChainVersion), m_secondaryToolChain(false)
 {
+    setLanguage(l);
     setTargetAbi(abi);
     setDisplayName(QString::fromLatin1("Android GCC (%1-%2)")
                    .arg(AndroidConfig::displayName(targetAbi()))
@@ -392,7 +393,8 @@ AndroidToolChainFactory::autodetectToolChainsForNdk(const FileName &ndkPath,
 
         AndroidToolChain *tc = findToolChain(compilerPath, alreadyKnown);
         if (!tc) {
-            tc = new AndroidToolChain(abi, version, ToolChain::AutoDetection);
+            tc = new AndroidToolChain(abi, version, ToolChain::Language::Cxx,
+                                      ToolChain::AutoDetection);
             tc->resetToolChain(compilerPath);
         }
         result.append(tc);
diff --git a/src/plugins/android/androidtoolchain.h b/src/plugins/android/androidtoolchain.h
index 06d0944956e..3de6a12eaa9 100644
--- a/src/plugins/android/androidtoolchain.h
+++ b/src/plugins/android/androidtoolchain.h
@@ -62,7 +62,8 @@ protected:
     DetectedAbisResult detectSupportedAbis() const override;
 
 private:
-    explicit AndroidToolChain(const ProjectExplorer::Abi &abi, const QString &ndkToolChainVersion, Detection d);
+    explicit AndroidToolChain(const ProjectExplorer::Abi &abi, const QString &ndkToolChainVersion,
+                              Language l, Detection d);
     AndroidToolChain();
     AndroidToolChain(const AndroidToolChain &);
 
diff --git a/src/plugins/ios/iosconfigurations.cpp b/src/plugins/ios/iosconfigurations.cpp
index e1748b93715..4e414e01e88 100644
--- a/src/plugins/ios/iosconfigurations.cpp
+++ b/src/plugins/ios/iosconfigurations.cpp
@@ -355,6 +355,7 @@ void IosConfigurations::setDeveloperPath(const FileName &devPath)
 static ClangToolChain *createToolChain(const Platform &platform)
 {
     ClangToolChain *toolChain = new ClangToolChain(ToolChain::AutoDetection);
+    toolChain->setLanguage(ToolChain::Language::Cxx);
     toolChain->setDisplayName(platform.name);
     toolChain->setPlatformCodeGenFlags(platform.backendFlags);
     toolChain->setPlatformLinkerFlags(platform.backendFlags);
diff --git a/src/plugins/projectexplorer/abstractmsvctoolchain.cpp b/src/plugins/projectexplorer/abstractmsvctoolchain.cpp
index d7eb341d5b0..302f049101f 100644
--- a/src/plugins/projectexplorer/abstractmsvctoolchain.cpp
+++ b/src/plugins/projectexplorer/abstractmsvctoolchain.cpp
@@ -42,6 +42,7 @@ namespace ProjectExplorer {
 namespace Internal {
 
 AbstractMsvcToolChain::AbstractMsvcToolChain(Core::Id typeId,
+                                             const Language &l,
                                              Detection d,
                                              const Abi &abi,
                                              const QString& vcvarsBat) : ToolChain(typeId, d),
@@ -53,6 +54,7 @@ AbstractMsvcToolChain::AbstractMsvcToolChain(Core::Id typeId,
     Q_ASSERT(abi.binaryFormat() == Abi::PEFormat);
     Q_ASSERT(abi.osFlavor() != Abi::WindowsMSysFlavor);
     Q_ASSERT(!m_vcvarsBat.isEmpty());
+    setLanguage(l);
 }
 
 AbstractMsvcToolChain::AbstractMsvcToolChain(Core::Id typeId, Detection d) :
diff --git a/src/plugins/projectexplorer/abstractmsvctoolchain.h b/src/plugins/projectexplorer/abstractmsvctoolchain.h
index be95a360833..17360fc7eb9 100644
--- a/src/plugins/projectexplorer/abstractmsvctoolchain.h
+++ b/src/plugins/projectexplorer/abstractmsvctoolchain.h
@@ -38,7 +38,8 @@ namespace Internal {
 class PROJECTEXPLORER_EXPORT AbstractMsvcToolChain : public ToolChain
 {
 public:
-    explicit AbstractMsvcToolChain(Core::Id typeId, Detection d, const Abi &abi, const QString& vcvarsBat);
+    explicit AbstractMsvcToolChain(Core::Id typeId, const Language &l, Detection d,
+                                   const Abi &abi, const QString& vcvarsBat);
     explicit AbstractMsvcToolChain(Core::Id typeId, Detection d);
 
     Abi targetAbi() const override;
diff --git a/src/plugins/projectexplorer/customtoolchain.cpp b/src/plugins/projectexplorer/customtoolchain.cpp
index e14562ca1b6..c715e8d6efb 100644
--- a/src/plugins/projectexplorer/customtoolchain.cpp
+++ b/src/plugins/projectexplorer/customtoolchain.cpp
@@ -88,7 +88,9 @@ static const char messageCapKeyC[] = "ProjectExplorer.CustomToolChain.MessageCap
 CustomToolChain::CustomToolChain(Detection d) :
     ToolChain(Constants::CUSTOM_TOOLCHAIN_TYPEID, d),
     m_outputParser(Gcc)
-{ }
+{
+    setLanguage(Language::Cxx);
+}
 
 QString CustomToolChain::typeDisplayName() const
 {
diff --git a/src/plugins/projectexplorer/gcctoolchain.cpp b/src/plugins/projectexplorer/gcctoolchain.cpp
index cc328d57af1..346af7aba30 100644
--- a/src/plugins/projectexplorer/gcctoolchain.cpp
+++ b/src/plugins/projectexplorer/gcctoolchain.cpp
@@ -776,7 +776,9 @@ bool GccToolChainFactory::canCreate()
 
 ToolChain *GccToolChainFactory::create()
 {
-    return createToolChain(false);
+    ToolChain *tc = createToolChain(false);
+    tc->setLanguage({ ToolChain::Language::Cxx });
+    return tc;
 }
 
 QList<ToolChain *> GccToolChainFactory::autoDetect(const QList<ToolChain *> &alreadyKnown)
@@ -860,6 +862,7 @@ QList<ToolChain *> GccToolChainFactory::autoDetectToolchains(const QString &comp
         tc->setTargetAbi(abi);
         tc->setOriginalTargetTriple(detectedAbis.originalTargetTriple);
         tc->setDisplayName(tc->defaultDisplayName()); // reset displayname
+        tc->setLanguage(ToolChain::Language::Cxx);
 
         result.append(tc.take());
     }
diff --git a/src/plugins/projectexplorer/msvctoolchain.cpp b/src/plugins/projectexplorer/msvctoolchain.cpp
index bb084b644e9..85918eec5d9 100644
--- a/src/plugins/projectexplorer/msvctoolchain.cpp
+++ b/src/plugins/projectexplorer/msvctoolchain.cpp
@@ -328,13 +328,14 @@ Utils::Environment MsvcToolChain::readEnvironmentSetting(Utils::Environment& env
 // --------------------------------------------------------------------------
 
 MsvcToolChain::MsvcToolChain(const QString &name, const Abi &abi,
-                             const QString &varsBat, const QString &varsBatArg, Detection d) :
-    MsvcToolChain(Constants::MSVC_TOOLCHAIN_TYPEID, name, abi, varsBat, varsBatArg, d)
+                             const QString &varsBat, const QString &varsBatArg, const Language &l,
+                             Detection d) :
+    MsvcToolChain(Constants::MSVC_TOOLCHAIN_TYPEID, name, abi, varsBat, varsBatArg, l, d)
 { }
 
 MsvcToolChain::MsvcToolChain(Core::Id typeId, const QString &name, const Abi &abi,
-                             const QString &varsBat, const QString &varsBatArg,
-                             Detection d) : AbstractMsvcToolChain(typeId, d, abi, varsBat),
+                             const QString &varsBat, const QString &varsBatArg, const Language &l,
+                             Detection d) : AbstractMsvcToolChain(typeId, l, d, abi, varsBat),
     m_varsBatArg(varsBatArg)
 {
     Q_ASSERT(!name.isEmpty());
@@ -342,8 +343,7 @@ MsvcToolChain::MsvcToolChain(Core::Id typeId, const QString &name, const Abi &ab
     setDisplayName(name);
 }
 
-MsvcToolChain::MsvcToolChain(Core::Id typeId)
-    : AbstractMsvcToolChain(typeId, ManualDetection)
+MsvcToolChain::MsvcToolChain(Core::Id typeId) : AbstractMsvcToolChain(typeId, ManualDetection)
 { }
 
 MsvcToolChain::MsvcToolChain() : MsvcToolChain(Constants::MSVC_TOOLCHAIN_TYPEID)
@@ -496,18 +496,15 @@ static const char clangClBinary[] = "clang-cl.exe";
 
 ClangClToolChain::ClangClToolChain(const QString &name, const QString &llvmDir,
                                    const Abi &abi,
-                                   const QString &varsBat, const QString &varsBatArg,
+                                   const QString &varsBat, const QString &varsBatArg, const Language &l,
                                    Detection d)
-    : MsvcToolChain(Constants::CLANG_CL_TOOLCHAIN_TYPEID, name, abi, varsBat, varsBatArg, d)
+    : MsvcToolChain(Constants::CLANG_CL_TOOLCHAIN_TYPEID, name, abi, varsBat, varsBatArg, l, d)
     , m_llvmDir(llvmDir)
     , m_compiler(Utils::FileName::fromString(m_llvmDir + QStringLiteral("/bin/") + QLatin1String(clangClBinary)))
-{
-}
+{ }
 
-ClangClToolChain::ClangClToolChain()
-    : MsvcToolChain(Constants::CLANG_CL_TOOLCHAIN_TYPEID)
-{
-}
+ClangClToolChain::ClangClToolChain() : MsvcToolChain(Constants::CLANG_CL_TOOLCHAIN_TYPEID)
+{ }
 
 bool ClangClToolChain::isValid() const
 {
@@ -632,7 +629,7 @@ static ToolChain *findOrCreateToolChain(const QList<ToolChain *> &alreadyKnown,
                                                       && mtc->varsBatArg() == varsBatArg;
                                          });
     if (!tc)
-        tc = new MsvcToolChain(name, abi, varsBat, varsBatArg, d);
+        tc = new MsvcToolChain(name, abi, varsBat, varsBatArg, ToolChain::Language::Cxx, d);
     return tc;
 }
 
@@ -671,6 +668,7 @@ static void detectCppBuildTools(QList<ToolChain *> *list)
                       e.format, e.wordSize);
         list->append(new MsvcToolChain(name + QLatin1String(e.postFix), abi,
                                        vcVarsBat, QLatin1String(e.varsBatArg),
+                                       ToolChain::Language::Cxx,
                                        ToolChain::AutoDetection));
     }
 }
@@ -715,7 +713,7 @@ static void detectClangClToolChain(QList<ToolChain *> *list)
         + Abi::toString(targetAbi.osFlavor()).toUpper();
     list->append(new ClangClToolChain(name, path, targetAbi,
                                       msvcToolChain->varsBat(), msvcToolChain->varsBatArg(),
-                                      ToolChain::AutoDetection));
+                                      ToolChain::Language::Cxx, ToolChain::AutoDetection));
 }
 
 QList<ToolChain *> MsvcToolChainFactory::autoDetect(const QList<ToolChain *> &alreadyKnown)
diff --git a/src/plugins/projectexplorer/msvctoolchain.h b/src/plugins/projectexplorer/msvctoolchain.h
index d544cebf743..20e67e6b746 100644
--- a/src/plugins/projectexplorer/msvctoolchain.h
+++ b/src/plugins/projectexplorer/msvctoolchain.h
@@ -55,7 +55,7 @@ public:
 
     explicit MsvcToolChain(const QString &name, const Abi &abi,
                            const QString &varsBat, const QString &varsBatArg,
-                           Detection d = ManualDetection);
+                           const Language &l, Detection d = ManualDetection);
     MsvcToolChain();
 
     Utils::FileNameList suggestedMkspecList() const override;
@@ -76,7 +76,7 @@ public:
 protected:
     explicit MsvcToolChain(Core::Id typeId, const QString &name, const Abi &abi,
                            const QString &varsBat, const QString &varsBatArg,
-                           Detection d);
+                           const Language &l, Detection d);
     explicit MsvcToolChain(Core::Id typeId);
 
     Utils::Environment readEnvironmentSetting(Utils::Environment& env) const override;
@@ -93,6 +93,7 @@ public:
     explicit ClangClToolChain(const QString &name, const QString &llvmDir,
                               const Abi &abi,
                               const QString &varsBat, const QString &varsBatArg,
+                              const Language &l,
                               Detection d = ManualDetection);
     ClangClToolChain();
 
diff --git a/src/plugins/projectexplorer/toolchainmanager.cpp b/src/plugins/projectexplorer/toolchainmanager.cpp
index 866f74b4aa5..c10c86b21fa 100644
--- a/src/plugins/projectexplorer/toolchainmanager.cpp
+++ b/src/plugins/projectexplorer/toolchainmanager.cpp
@@ -388,6 +388,7 @@ void ToolChainManager::notifyAboutUpdate(ToolChain *tc)
 
 bool ToolChainManager::registerToolChain(ToolChain *tc)
 {
+    QTC_ASSERT(tc->language() != ToolChain::Language::None, return false);
     QTC_ASSERT(d->m_writer, return false);
 
     if (!tc || d->m_toolChains.contains(tc))
@@ -433,7 +434,10 @@ public:
         ToolChain("TestToolChainType", d),
         token(t),
         m_valid(v)
-    { m_toolChains.append(this); }
+    {
+        m_toolChains.append(this);
+        setLanguage(ToolChain::Language::Cxx);
+    }
 
     static QList<TTC *> toolChains();
     static bool hasToolChains() { return !m_toolChains.isEmpty(); }
diff --git a/src/plugins/projectexplorer/wincetoolchain.cpp b/src/plugins/projectexplorer/wincetoolchain.cpp
index 3c3ce905126..741d5985ae8 100644
--- a/src/plugins/projectexplorer/wincetoolchain.cpp
+++ b/src/plugins/projectexplorer/wincetoolchain.cpp
@@ -236,8 +236,9 @@ WinCEToolChain::WinCEToolChain(const QString &name,
                                const QString &binPath,
                                const QString &includePath,
                                const QString &libPath,
+                               const Language &l,
                                Detection d) :
-    AbstractMsvcToolChain(Constants::WINCE_TOOLCHAIN_TYPEID, d, abi, vcvarsBat),
+    AbstractMsvcToolChain(Constants::WINCE_TOOLCHAIN_TYPEID, l, d, abi, vcvarsBat),
     m_msvcVer(msvcVer),
     m_ceVer(ceVer),
     m_binPath(binPath),
@@ -368,7 +369,8 @@ static ToolChain *findOrCreateToolChain(const QList<ToolChain *> &alreadyKnown,
                                                   && cetc->libPath() == libPath;
                                          });
     if (!tc)
-        tc = new WinCEToolChain(name, abi, vcvarsBat, msvcVer, ceVer, binPath, includePath, libPath, d);
+        tc = new WinCEToolChain(name, abi, vcvarsBat, msvcVer, ceVer, binPath, includePath, libPath,
+                                ProjectExplorer::ToolChain::Language::Cxx, d);
     return tc;
 }
 
diff --git a/src/plugins/projectexplorer/wincetoolchain.h b/src/plugins/projectexplorer/wincetoolchain.h
index 376b25fe048..918d9f02867 100644
--- a/src/plugins/projectexplorer/wincetoolchain.h
+++ b/src/plugins/projectexplorer/wincetoolchain.h
@@ -43,6 +43,7 @@ public:
                    const QString &binPath,
                    const QString &includePath,
                    const QString &libPath,
+                   const Language &l,
                    Detection d = ManualDetection);
 
     Utils::FileNameList suggestedMkspecList() const override;
diff --git a/src/plugins/qnx/qnxtoolchain.cpp b/src/plugins/qnx/qnxtoolchain.cpp
index 6eda4a2e7a8..c186e96bb8d 100644
--- a/src/plugins/qnx/qnxtoolchain.cpp
+++ b/src/plugins/qnx/qnxtoolchain.cpp
@@ -62,6 +62,13 @@ QnxToolChain::QnxToolChain(ToolChain::Detection d)
     : GccToolChain(Constants::QNX_TOOLCHAIN_ID, d)
 { }
 
+QnxToolChain::QnxToolChain(Language l, ToolChain::Detection d)
+    : QnxToolChain(d)
+{
+    setLanguage(l);
+}
+
+
 QString QnxToolChain::typeDisplayName() const
 {
     return QnxToolChainFactory::tr("QCC");
diff --git a/src/plugins/qnx/qnxtoolchain.h b/src/plugins/qnx/qnxtoolchain.h
index 193e7e36f8c..551c9c90682 100644
--- a/src/plugins/qnx/qnxtoolchain.h
+++ b/src/plugins/qnx/qnxtoolchain.h
@@ -35,6 +35,7 @@ class QnxToolChain : public ProjectExplorer::GccToolChain
 {
 public:
     explicit QnxToolChain(Detection d);
+    explicit QnxToolChain(Language l, Detection d);
 
     QString typeDisplayName() const override;