fix clang testsuite crash (#2341)

lib/tokenize.cpp

@@ -10890,6 +10890,8 @@ void Tokenizer::simplifyOperatorName()
                 op += par->strAt(1);
                 par = par->tokAt(2);
                 done = true;
+            } else if (par->str() != "(") {
+                syntaxError(par);
             }
         }
 

test/testgarbage.cpp

@@ -237,6 +237,7 @@ private:
         TEST_CASE(garbageCode203); // #8972
         TEST_CASE(garbageCode204);
         TEST_CASE(garbageCode205);
+        TEST_CASE(garbageCode206);
 
         TEST_CASE(garbageCodeFuzzerClientMode1); // test cases created with the fuzzer client, mode 1
 
@@ -1625,6 +1626,15 @@ private:
                   "}"); // don't crash
     }
 
+    void garbageCode206() {
+        {
+            ASSERT_EQUALS("[test.cpp:1] syntax error", getSyntaxError("void foo() { for (auto operator new : int); }"));
+        }
+        {
+            ASSERT_EQUALS("[test.cpp:1] syntax error", getSyntaxError("void foo() { for (a operator== :) }"));
+        }
+    }
+
     void syntaxErrorFirstToken() {
         ASSERT_THROW(checkCode("&operator(){[]};"), InternalError); // #7818
         ASSERT_THROW(checkCode("*(*const<> (size_t); foo) { } *(*const (size_t)() ; foo) { }"), InternalError); // #6858