Check if member function modifies the variable (#1350)

* Check if member function modifies the variable

* Check for const pointer

* Add test for const condition

* Add more null checking

* Add todo assert for FN

lib/astutils.cpp

@@ -779,6 +779,21 @@ bool isVariableChanged(const Token *start, const Token *end, const unsigned int
         if (isLikelyStreamRead(cpp, tok->previous()))
             return true;
 
+        // Member function call
+        if(Token::Match(tok, "%name% . %name% (")) {
+            const Variable * var = tok->variable();
+            bool isConst = var && var->isConst();
+            if(!isConst && var) {
+                const ValueType * valueType = var->valueType();
+                isConst = (valueType && valueType->pointer == 1 && valueType->constness == 1);
+            }
+                        
+            const Token *ftok = tok->tokAt(2);
+            const Function * fun = ftok->function();
+            if(!isConst && (!fun || !fun->isConst()))
+                return true;
+        }
+
         const Token *ftok = tok;
         while (ftok && !Token::Match(ftok, "[({[]"))
             ftok = ftok->astParent();

test/testcondition.cpp

@@ -71,6 +71,7 @@ private:
         TEST_CASE(incorrectLogicOperator9);
         TEST_CASE(incorrectLogicOperator10); // enum
         TEST_CASE(incorrectLogicOperator11);
+        TEST_CASE(incorrectLogicOperator12);
         TEST_CASE(secondAlwaysTrueFalseWhenFirstTrueError);
         TEST_CASE(incorrectLogicOp_condSwapping);
         TEST_CASE(testBug5895);
@@ -1233,6 +1234,50 @@ private:
         ASSERT_EQUALS("[test.cpp:1]: (warning) Logical conjunction always evaluates to false: i == n && i < n.\n", errout.str());
     }
 
+    void incorrectLogicOperator12() { // #8696
+        check("struct A {\n"
+              "    void f() const;\n"
+              "};\n"
+              "void foo(A a) {\n"
+              "  A x = a;\n"
+              "  A y = a;\n"
+              "  y.f();\n"
+              "  if (a > x && a < y)\n"
+              "    return;\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:8]: (warning) Logical conjunction always evaluates to false: a > x && a < y.\n", errout.str());
+
+        check("struct A {\n"
+              "    void f();\n"
+              "};\n"
+              "void foo(A a) {\n"
+              "  A x = a;\n"
+              "  A y = a;\n"
+              "  y.f();\n"
+              "  if (a > x && a < y)\n"
+              "    return;\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
+
+        check("void foo(A a) {\n"
+              "  A x = a;\n"
+              "  A y = a;\n"
+              "  y.f();\n"
+              "  if (a > x && a < y)\n"
+              "    return;\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
+
+        check("void foo(A a) {\n"
+              "  const A x = a;\n"
+              "  const A y = a;\n"
+              "  y.f();\n"
+              "  if (a > x && a < y)\n"
+              "    return;\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:5]: (warning) Logical conjunction always evaluates to false: a > x && a < y.\n", errout.str());
+    }
+
     void secondAlwaysTrueFalseWhenFirstTrueError() {
         check("void f(int x) {\n"
               "    if (x > 5 && x != 1)\n"

test/testvalueflow.cpp

@@ -3126,12 +3126,19 @@ private:
         ASSERT_EQUALS(true, values.size()==1U && values.front().isUninitValue());
 
         code = "void f() {\n"
-               "    C *c;\n"
+               "    const C *c;\n"
                "    if (c->x() == 4) {}\n"
                "}";
         values = tokenValues(code, "c .");
         ASSERT_EQUALS(true, values.size()==1U && values.front().isUninitValue());
 
+        code = "void f() {\n"
+               "    C *c;\n"
+               "    if (c->x() == 4) {}\n"
+               "}";
+        values = tokenValues(code, "c .");
+        TODO_ASSERT_EQUALS(true, false, values.size()==1U && values.front().isUninitValue());
+
         code = "void f() {\n"
                "    int **x;\n"
                "    y += 10;\n"