The moc executable loops through headers on CPLUS_INCLUDE_PATH and stumbles on the GCC internal _GLIBCXX_VISIBILITY macro. Tell it to ignore it as it is not supposed to be looking there to begin with. Upstream report: https://bugreports.qt.io/browse/QTBUG-83160 diff --git a/qtbase/src/tools/moc/main.cpp b/qtbase/src/tools/moc/main.cpp --- a/qtbase/src/tools/moc/main.cpp +++ b/qtbase/src/tools/moc/main.cpp @@ -238,6 +238,7 @@ int runMoc(int argc, char **argv) dummyVariadicFunctionMacro.arguments += Symbol(0, PP_IDENTIFIER, "__VA_ARGS__"); pp.macros["__attribute__"] = dummyVariadicFunctionMacro; pp.macros["__declspec"] = dummyVariadicFunctionMacro; + pp.macros["_GLIBCXX_VISIBILITY"] = dummyVariadicFunctionMacro; QString filename; QString output;