Fix #11679 FP knownArgument with known return value (#5007)

* Fix #11679 FP knownArgument with known return value

* Add test for #11051

Author: chrchr-github

lib/checkcondition.cpp

@@ -1498,6 +1498,8 @@ void CheckCondition::alwaysTrueFalse()
                 continue;
             if (Token::simpleMatch(tok, ":"))
                 continue;
+            if (Token::Match(tok->astOperand1(), "%name% (") && Token::simpleMatch(tok->astParent(), "return"))
+                continue;
             if (tok->isComparisonOp() && isWithoutSideEffects(mTokenizer->isCPP(), tok->astOperand1()) &&
                 isSameExpression(mTokenizer->isCPP(),
                                  true,

lib/checkother.cpp

@@ -3597,6 +3597,8 @@ void CheckOther::checkKnownArgument()
                 continue;
             if (isConstVarExpression(tok))
                 continue;
+            if (Token::Match(tok->astOperand1(), "%name% ("))
+                continue;
             const Token * tok2 = tok;
             if (isCPPCast(tok2))
                 tok2 = tok2->astOperand2();

test/testcondition.cpp

@@ -4504,6 +4504,20 @@ class TestCondition : public TestFixture {
               "    if (j == 1) {}\n"
               "}\n");
         ASSERT_EQUALS("", errout.str());
+
+        check("void h(int);\n" // #11679
+              "bool g(int a) { h(a); return false; }\n"
+              "bool f(int i) {\n"
+              "    return g(i);\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
+
+        check("void f(std::string a) {\n" // #11051
+              "    a = \"x\";\n"
+              "    if (a == \"x\") {}\n"
+              "    return a;\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:3]: (style) Condition 'a==\"x\"' is always true\n", errout.str());
     }
 
     void alwaysTrueSymbolic()

test/testother.cpp

@@ -10696,6 +10696,15 @@ class TestOther : public TestFixture {
               "    dostuff(self->maxsize * sizeof(intptr_t));\n"
               "}");
         ASSERT_EQUALS("", errout.str());
+
+        // #11679
+        check("bool g(int);\n"
+              "void h(int);\n"
+              "int k(int a) { h(a); return 0; }\n"
+              "void f(int i) {\n"
+              "    if (g(k(i))) {}\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
     }
 
     void knownArgumentHiddenVariableExpression() {