Fixed #6877 (ValueFlow: valueFlowForward, after goto label the value is not known)

lib/valueflow.cpp

@@ -993,6 +993,13 @@ static bool valueFlowForward(Token * const               startToken,
             }
         }
 
+        if (Token::Match(tok2, "[;{}] %name% :")) {
+            for (std::list<ValueFlow::Value>::iterator it = values.begin(); it != values.end(); ++it)
+                it->changeKnownToPossible();
+            tok2 = tok2->tokAt(2);
+            continue;
+        }
+
         if (Token::Match(tok2, "sizeof|typeof|typeid ("))
             tok2 = tok2->linkAt(1);
 

test/testvalueflow.cpp

@@ -1651,6 +1651,15 @@ private:
         ASSERT_EQUALS(1, value.intvalue);
         ASSERT(value.isPossible());
 
+        code = "void f() {\n"
+               "  int x = 0;\n"
+               "a:\n"
+               "  a = x + 1;\n" // <- possible value
+               "}";
+        value = valueOfTok(code, "+");
+        ASSERT_EQUALS(1, value.intvalue);
+        ASSERT(value.isPossible());
+
         // after condition
         code = "int f(int x) {\n"
                "  if (x == 4) {}\n"