Fix #12008 debug: Executable scope 'x' with unknown function. (#5588)

lib/tokenize.cpp

@@ -1693,7 +1693,7 @@ void Tokenizer::simplifyTypedefCpp()
                         } else {
                             if (scope == 0 && !(classLevel > 1 && tok2 == spaceInfo[classLevel - 1].bodyEnd))
                                 break;
-                            --scope;
+                            scope = std::max(scope - 1, 0);
                         }
                     }
 

test/testsimplifytypedef.cpp

@@ -3395,6 +3395,18 @@ private:
                "void N::T::f(V*) {}\n"
                "namespace N {}\n";
         ASSERT_EQUALS("namespace N { struct S { } ; struct T { void f ( int * ) ; } ; } void N :: T :: f ( int * ) { }", tok(code));
+
+        code = "namespace N {\n" // #12008
+               "    typedef char U;\n"
+               "    typedef int V;\n"
+               "    struct S {\n"
+               "        S(V* v);\n"
+               "    };\n"
+               "}\n"
+               "void f() {}\n"
+               "N::S::S(V* v) {}\n"
+               "namespace N {}\n";
+        ASSERT_EQUALS("namespace N { struct S { S ( int * v ) ; } ; } void f ( ) { } N :: S :: S ( int * v ) { }", tok(code));
     }
 
     void simplifyTypedef147() {