Tokenizer; Warn about unknown macro used in string concatenation

lib/tokenize.cpp

@@ -9332,6 +9332,15 @@ void Tokenizer::reportUnknownMacros()
             }
         }
     }
+
+    // String concatenation with unknown macros
+    for (const Token *tok = tokens(); tok; tok = tok->next()) {
+        if (Token::Match(tok, "%str% %name% (") && Token::Match(tok->linkAt(2), ") %str%")) {
+            if (list.isKeyword(tok->next()->str()))
+                continue;
+            unknownMacroError(tok->next());
+        }
+    }
 }
 
 void Tokenizer::findGarbageCode() const

test/testtokenize.cpp

@@ -7982,6 +7982,9 @@ private:
 
         const char code2[] = "void foo() { dostuff(x 0); }";
         ASSERT_THROW(tokenizeAndStringify(code2), InternalError);
+
+        const char code3[] = "f(\"1\" __stringify(48) \"1\");";
+        ASSERT_THROW(tokenizeAndStringify(code3), InternalError);
     }
 
     void findGarbageCode() { // Test Tokenizer::findGarbageCode()