Fix #14392 FN knownConditionTrueFalse (assigning function call result)

.selfcheck_suppressions

@@ -40,5 +40,6 @@ naming-privateMemberVariable:externals/tinyxml2/tinyxml2.h
 functionStatic:externals/tinyxml2/tinyxml2.cpp
 funcArgNamesDifferent:externals/tinyxml2/tinyxml2.cpp
 nullPointerRedundantCheck:externals/tinyxml2/tinyxml2.cpp
+knownConditionTrueFalse:externals/tinyxml2/tinyxml2.cpp
 useStlAlgorithm:externals/simplecpp/simplecpp.cpp
 missingMemberCopy:externals/simplecpp/simplecpp.h

lib/checkcondition.cpp

@@ -1545,6 +1545,8 @@ void CheckCondition::alwaysTrueFalse()
                     condition = parent->astParent()->astParent()->previous();
                 else if (Token::Match(tok, "%comp%"))
                     condition = tok;
+                else if (tok->str() == "(" && astIsBool(parent) && Token::Match(parent, "%assign%"))
+                    condition = tok;
                 else
                     continue;
             }

test/testcondition.cpp

@@ -4787,6 +4787,19 @@ class TestCondition : public TestFixture {
               "    }\n"
               "}\n");
         ASSERT_EQUALS("", errout_str());
+
+        check("struct S {\n" // #14392
+              "    bool g() const { return m; }\n"
+              "    bool m{};\n"
+              "};\n"
+              "void f(S s) {\n"
+              "    if (s.g()) {\n"
+              "        bool b = s.g();\n"
+              "        return b;\n"
+              "    }\n"
+              "    return false;\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:6:12] -> [test.cpp:7:21]: (style) Condition 's.g()' is always true [knownConditionTrueFalse]\n", errout_str());
     }
 
     void alwaysTrueSymbolic()