3 files changed, 65 insertions, 5 deletions
diff --git a/sources/shiboken2/ApiExtractor/clangparser/clangparser.cpp b/sources/shiboken2/ApiExtractor/clangparser/clangparser.cpp
index ddafcdb04..301b4211e 100644
--- a/sources/shiboken2/ApiExtractor/clangparser/clangparser.cpp
+++ b/sources/shiboken2/ApiExtractor/clangparser/clangparser.cpp
@@ -196,11 +196,6 @@ static CXTranslationUnit createTranslationUnit(CXIndex index,
         | CXTranslationUnit_Incomplete;
 
     static const QByteArrayList defaultArgs = {
-#if defined(Q_CC_MSVC) && _MSC_VER > 1900
-        "-std=c++1z", // Fixes constexpr errors in MSVC2017 library headers with Clang 4.1
-#else
-        "-std=c++14", // ! otherwise, t.h is parsed as "C"
-#endif
 #ifndef Q_OS_WIN
         "-fPIC",
 #endif
diff --git a/sources/shiboken2/ApiExtractor/clangparser/compilersupport.cpp b/sources/shiboken2/ApiExtractor/clangparser/compilersupport.cpp
index 9f4f7dc03..820909713 100644
--- a/sources/shiboken2/ApiExtractor/clangparser/compilersupport.cpp
+++ b/sources/shiboken2/ApiExtractor/clangparser/compilersupport.cpp
@@ -40,12 +40,19 @@
 #include <QtCore/QStringList>
 #include <QtCore/QVersionNumber>
 
+#include <clang-c/Index.h>
+
 #include <string.h>
 #include <algorithm>
 #include <iterator>
 
 namespace clang {
 
+QVersionNumber libClangVersion()
+{
+    return QVersionNumber(CINDEX_VERSION_MAJOR, CINDEX_VERSION_MINOR);
+}
+
 static bool runProcess(const QString &program, const QStringList &arguments,
                        QByteArray *stdOutIn = nullptr, QByteArray *stdErrIn = nullptr)
 {
@@ -271,4 +278,47 @@ QByteArrayList emulatedCompilerOptions()
     return result;
 }
 
+LanguageLevel emulatedCompilerLanguageLevel()
+{
+#if defined(Q_CC_MSVC) && _MSC_VER > 1900
+    // Fixes constexpr errors in MSVC2017 library headers with Clang 4.1..5.X (0.45 == Clang 6).
+    if (libClangVersion() < QVersionNumber(0, 45))
+        return LanguageLevel::Cpp1Z;
+#endif // Q_CC_MSVC && _MSC_VER > 1900
+    return LanguageLevel::Cpp14; // otherwise, t.h is parsed as "C"
+}
+
+struct LanguageLevelMapping
+{
+    const char *option;
+    LanguageLevel level;
+};
+
+static const LanguageLevelMapping languageLevelMapping[] =
+{
+    {"c++11", LanguageLevel::Cpp11},
+    {"c++14", LanguageLevel::Cpp14},
+    {"c++17", LanguageLevel::Cpp17},
+    {"c++20", LanguageLevel::Cpp20},
+    {"c++1z", LanguageLevel::Cpp1Z}
+};
+
+const char *languageLevelOption(LanguageLevel l)
+{
+    for (const LanguageLevelMapping &m : languageLevelMapping) {
+        if (m.level == l)
+            return m.option;
+    }
+    return nullptr;
+}
+
+LanguageLevel languageLevelFromOption(const char *o)
+{
+    for (const LanguageLevelMapping &m : languageLevelMapping) {
+        if (!strcmp(m.option, o))
+            return m.level;
+    }
+    return LanguageLevel::Default;
+}
+
 } // namespace clang
diff --git a/sources/shiboken2/ApiExtractor/clangparser/compilersupport.h b/sources/shiboken2/ApiExtractor/clangparser/compilersupport.h
index 68d09f6f5..d9e213e73 100644
--- a/sources/shiboken2/ApiExtractor/clangparser/compilersupport.h
+++ b/sources/shiboken2/ApiExtractor/clangparser/compilersupport.h
@@ -31,10 +31,25 @@
 
 #include <QtCore/QByteArrayList>
 
+QT_FORWARD_DECLARE_CLASS(QVersionNumber)
+
+enum class LanguageLevel {
+    Default,
+    Cpp11,
+    Cpp14,
+    Cpp17,
+    Cpp20,
+    Cpp1Z
+};
+
 namespace clang {
+QVersionNumber libClangVersion();
 
 QByteArrayList emulatedCompilerOptions();
+LanguageLevel emulatedCompilerLanguageLevel();
 
+const char *languageLevelOption(LanguageLevel l);
+LanguageLevel languageLevelFromOption(const char *);
 } // namespace clang
 
 #endif // COMPILERSUPPORT_H