add language/standard check

Author: ludviggunne

lib/checkfunctions.cpp

@@ -329,7 +329,7 @@ void CheckFunctionsImpl::checkMissingReturn()
             continue;
         if (Function::returnsVoid(function, true))
             continue;
-        if (Function::isCoroutine(function))
+        if (Function::isCoroutine(function, mSettings.standards, *mTokenizer))
             continue;
         const Token *errorToken = checkMissingReturnScope(scope->bodyEnd, mSettings.library);
         if (errorToken)

lib/symboldatabase.cpp

@@ -3407,8 +3407,10 @@ bool Function::returnsVoid(const Function* function, bool unknown)
     });
 }
 
-bool Function::isCoroutine(const Function* function)
+bool Function::isCoroutine(const Function* function, const Standards &standards, const Tokenizer &tokens)
 {
+    if (!tokens.isCPP() || standards.cpp < Standards::CPP20)
+        return false;
     if (!function->functionScope)
         return false;
     const Scope *scope = function->functionScope;

lib/symboldatabase.h

@@ -945,7 +945,7 @@ class CPPCHECKLIB Function {
     static bool returnsStandardType(const Function* function, bool unknown = false);
 
     static bool returnsVoid(const Function* function, bool unknown = false);
-    static bool isCoroutine(const Function* function);
+    static bool isCoroutine(const Function* function, const Standards &standards, const Tokenizer &tokens);
 
     static std::vector<const Token*> findReturns(const Function* f);