Clang: Properly generate macros with clang-cl

Clang-cl can work with different command line styles but
it seems that it's a bad idea to mix them. So let's use gcc
toolchain methods only when --driver-mode=g++ is specified
and ones from msvc toolchain in other cases.

Change-Id: I071a124a07b31bce2a0a5594ff8ca79d9ed84716
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>

src/plugins/projectexplorer/abstractmsvctoolchain.cpp

@@ -129,7 +129,8 @@ ToolChain::MacroInspectionRunner AbstractMsvcToolChain::createMacroInspectionRun
 
         const Macros macros = msvcPredefinedMacros(filteredFlags, env);
 
-        const auto report = MacroInspectionReport{macros, msvcLanguageVersion(lang, macros)};
+        const auto report = MacroInspectionReport{macros,
+                                                  msvcLanguageVersion(filteredFlags, lang, macros)};
         macroCache->insert(filteredFlags, report);
 
         return report;

src/plugins/projectexplorer/abstractmsvctoolchain.h

@@ -98,7 +98,8 @@ protected:
     // Function must be thread-safe!
     virtual Macros msvcPredefinedMacros(const QStringList cxxflags,
                                         const Utils::Environment& env) const = 0;
-    virtual LanguageVersion msvcLanguageVersion(const Core::Id &language,
+    virtual LanguageVersion msvcLanguageVersion(const QStringList cxxflags,
+                                                const Core::Id &language,
                                                 const Macros &macros) const = 0;
 
     Utils::FileName m_debuggerCommand;

src/plugins/projectexplorer/msvctoolchain.cpp

@@ -525,7 +525,8 @@ Macros MsvcToolChain::msvcPredefinedMacros(const QStringList cxxflags,
 //
 // For _MSV_VER values, see https://docs.microsoft.com/en-us/cpp/preprocessor/predefined-macros?view=vs-2017.
 //
-LanguageVersion MsvcToolChain::msvcLanguageVersion(const Core::Id &language,
+LanguageVersion MsvcToolChain::msvcLanguageVersion(const QStringList /*cxxflags*/,
+                                                   const Core::Id &language,
                                                    const Macros &macros) const
 {
     int mscVer = -1;
@@ -1120,6 +1121,9 @@ bool ClangClToolChain::operator ==(const ToolChain &other) const
 Macros ClangClToolChain::msvcPredefinedMacros(const QStringList cxxflags,
                                               const Utils::Environment &env) const
 {
+    if (!cxxflags.contains("--driver-mode=g++"))
+        return MsvcToolChain::msvcPredefinedMacros(cxxflags, env);
+
     Utils::SynchronousProcess cpp;
     cpp.setEnvironment(env.toStringList());
     cpp.setWorkingDirectory(Utils::TemporaryDirectory::masterDirectoryPath());
@@ -1138,10 +1142,13 @@ Macros ClangClToolChain::msvcPredefinedMacros(const QStringList cxxflags,
     return Macro::toMacros(response.allRawOutput());
 }
 
-LanguageVersion ClangClToolChain::msvcLanguageVersion(const Core::Id &language,
+LanguageVersion ClangClToolChain::msvcLanguageVersion(const QStringList cxxflags,
+                                                      const Core::Id &language,
                                                       const Macros &macros) const
 {
-    return ToolChain::languageVersion(language, macros);
+    if (cxxflags.contains("--driver-mode=g++"))
+        return ToolChain::languageVersion(language, macros);
+    return MsvcToolChain::msvcLanguageVersion(cxxflags, language, macros);
 }
 
 // --------------------------------------------------------------------------

src/plugins/projectexplorer/msvctoolchain.h

@@ -94,7 +94,8 @@ protected:
     // Function must be thread-safe!
     Macros msvcPredefinedMacros(const QStringList cxxflags,
                                 const Utils::Environment &env) const override;
-    LanguageVersion msvcLanguageVersion(const Core::Id &language,
+    LanguageVersion msvcLanguageVersion(const QStringList cxxflags,
+                                        const Core::Id &language,
                                         const Macros &macros) const override;
 
     struct GenerateEnvResult
@@ -141,7 +142,8 @@ public:
     void resetMsvcToolChain(const MsvcToolChain *base = nullptr);
     Macros msvcPredefinedMacros(const QStringList cxxflags,
                                 const Utils::Environment &env) const override;
-    LanguageVersion msvcLanguageVersion(const Core::Id &language,
+    LanguageVersion msvcLanguageVersion(const QStringList cxxflags,
+                                        const Core::Id &language,
                                         const Macros &macros) const override;
 
     bool operator ==(const ToolChain &) const override;