Fixed #6378 (valueFlowForward: decrement not handled)

lib/valueflow.cpp

@@ -1043,13 +1043,6 @@ static bool valueFlowForward(Token * const               startToken,
                 return false;
             }
 
-            // bailout increment/decrement for now..
-            if (Token::Match(tok2->previous(), "++|-- %name%") || Token::Match(tok2, "%name% ++|--")) {
-                if (settings->debugwarnings)
-                    bailout(tokenlist, errorLogger, tok2, "increment/decrement of " + tok2->str());
-                return false;
-            }
-
             // bailout: possible assignment using >>
             if (Token::Match(tok2->previous(), ">> %name% >>|;")) {
                 const Token *parent = tok2->previous();
@@ -1081,6 +1074,34 @@ static bool valueFlowForward(Token * const               startToken,
                     setTokenValue(tok2, *it);
             }
 
+            // increment/decrement
+            if (Token::Match(tok2->previous(), "++|-- %name%") || Token::Match(tok2, "%name% ++|--")) {
+                const bool pre   = Token::Match(tok2->previous(), "++|--");
+                Token * const op = pre ? tok2->previous() : tok2->next();
+                const bool inc   = (op->str() == "++");
+                std::list<ValueFlow::Value>::iterator it;
+                // Erase values that are not int values..
+                for (it = values.begin(); it != values.end();) {
+                    if (it->tokvalue)
+                        it = values.erase(it);
+                    else
+                        ++it;
+                }
+                if (values.empty()) {
+                    if (settings->debugwarnings)
+                        bailout(tokenlist, errorLogger, tok2, "increment/decrement of " + tok2->str());
+                    return false;
+                }
+                // Perform increment/decrement..
+                for (it = values.begin(); it != values.end(); ++it) {
+                    if (!pre)
+                        setTokenValue(op, *it);
+                    it->intvalue += (inc ? 1 : -1);
+                    if (pre)
+                        setTokenValue(op, *it);
+                }
+            }
+
             // bailout if address of var is taken..
             if (tok2->astParent() && tok2->astParent()->str() == "&" && !tok2->astParent()->astOperand2()) {
                 if (settings->debugwarnings)

test/testsimplifytypedef.cpp

@@ -1099,7 +1099,7 @@ private:
                       "[test.cpp:20] -> [test.cpp:1]: (style, inconclusive) The function parameter 'A' hides a typedef with the same name.\n"
                       "[test.cpp:21] -> [test.cpp:1]: (style, inconclusive) The variable 'A' hides a typedef with the same name.\n"
                       "[test.cpp:24] -> [test.cpp:1]: (style, inconclusive) The typedef 'A' hides a typedef with the same name.\n"
-                      "[test.cpp:21]: (debug) ValueFlow bailout: increment/decrement of a\n", errout.str());
+                      , errout.str());
     }
 
     void simplifyTypedef36() {

test/testvalueflow.cpp

@@ -641,6 +641,7 @@ private:
                "    return x;\n"
                "}";
         ASSERT_EQUALS(false, testValueOfX(code, 4U, 9));
+        ASSERT_EQUALS(true, testValueOfX(code, 4U, 8));
 
         code = "void f() {\n"
                "    int x = 0;\n"
@@ -1346,7 +1347,7 @@ private:
                "  for (x = 0; x < 20; x++) {}\n"
                "  a = x++;\n"
                "}\n";
-        TODO_ASSERT_EQUALS(true, false, testValueOfX(code, 4U, 20));
+        ASSERT_EQUALS(true, testValueOfX(code, 4U, 20));
 
         code = "void f() {\n"
                "  int x;\n"