Fixed #4102 (False positive: 'find('=') + 1U' can't be replaced with compare)

.travis.yml

@@ -5,4 +5,4 @@ compiler:
 script:
   - make test
   - $CXX -o cppcheck -O2 cli/*.cpp lib/*.cpp -Ilib
-  - ./cppcheck --error-exitcode=1 -Ilib --enable=style --suppress=duplicateBranch --suppress=stlIfStrFind -q cli gui lib -igui/test
+  - ./cppcheck --error-exitcode=1 -Ilib --enable=style --suppress=duplicateBranch -q cli gui lib -igui/test

lib/checkstl.cpp

@@ -720,14 +720,18 @@ static bool if_findCompare(const Token * const tokBack)
     const Token *tok = tokBack;
     while (tok && tok->str() == ")") {
         tok = tok->next();
-        if (Token::Match(tok,",|==|!="))
-            return true;
+
         if (Token::Match(tok, ") !!{") &&
             tok->link()->previous() &&
             (Token::Match(tok->link()->previous(),",|==|!=") ||
              tok->link()->previous()->isName()))
             return true;
     }
+
+    if (Token::Match(tok,",|==|!="))
+        return true;
+    if (tok->isArithmeticalOp()) // result is used in some calculation
+        return true;  // TODO: check if there is a comparison of the result somewhere
     return false;
 }
 

test/teststl.cpp

@@ -1372,6 +1372,12 @@ private:
               "    if ((!s1.empty()) && (0 == s1.find(s2))) { }\n"
               "}");
         ASSERT_EQUALS("[test.cpp:3]: (performance) Inefficient usage of string::find in condition; string::compare would be faster.\n", errout.str());
+
+        // #4102
+        check("void f(const std::string &define) {\n"
+              "    if (define.find(\"=\") + 1U == define.size());\n"
+              "}");
+        ASSERT_EQUALS("", errout.str());
     }