Fixed more false negatives (and recently introduced false positives) literalWithCharPtrCompare by using ValueType

Merged from LCppC.

Author: PKEuS

lib/checkstring.cpp

@@ -181,46 +181,18 @@ void CheckString::checkSuspiciousStringCompare()
             else if (!Token::Match(litTok, "%char%|%num%|%str%"))
                 continue;
 
-            if (mTokenizer->isCPP() && (!varTok->valueType() || !varTok->valueType()->isIntegral()))
+            if (varTok->isLiteral())
                 continue;
 
-            // Pointer addition?
-            if (varTok->str() == "+" && mTokenizer->isC()) {
-                const Token * const tokens[2] = { varTok->astOperand1(), varTok->astOperand2() };
-                for (const Token * t : tokens) {
-                    while (t && (t->str() == "." || t->str() == "::"))
-                        t = t->astOperand2();
-                    if (t && t->variable() && t->variable()->isPointer())
-                        varTok = t;
-                }
-            }
-
-            const Token* oldVarTok = varTok;
-            while (varTok->str() == "*") {
-                if (!mTokenizer->isC() || varTok->astOperand2() != nullptr || litTok->tokType() != Token::eString)
-                    break;
-                varTok = varTok->astOperand1();
-            }
-
-            if (mTokenizer->isC() && varTok->str() == "&")
-                varTok = varTok->astOperand1();
-
-            if (varTok->str() == "[")
-                varTok = varTok->astOperand1();
-
-            while (varTok && (varTok->str() == "." || varTok->str() == "::"))
-                varTok = varTok->astOperand2();
-            if (!varTok || !varTok->isName())
+            const ValueType* varType = varTok->valueType();
+            if (mTokenizer->isCPP() && (!varType || !varType->isIntegral()))
                 continue;
 
-            const Variable *var = varTok->variable();
-
-            const bool ischar(litTok->tokType() == Token::eChar);
             if (litTok->tokType() == Token::eString) {
-                if (mTokenizer->isC() || (var && var->isArrayOrPointer()))
-                    suspiciousStringCompareError(tok, oldVarTok->expressionString(), litTok->isLong());
-            } else if (ischar && var && var->isPointer()) {
-                suspiciousStringCompareError_char(tok, oldVarTok->expressionString());
+                if (mTokenizer->isC() || (varType && varType->pointer))
+                    suspiciousStringCompareError(tok, varTok->expressionString(), litTok->isLong());
+            } else if (litTok->tokType() == Token::eChar && varType && varType->pointer) {
+                suspiciousStringCompareError_char(tok, varTok->expressionString());
             }
         }
     }

test/teststring.cpp

@@ -317,7 +317,7 @@ class TestString : public TestFixture {
         check("bool foo(char* c) {\n"
               "    return \"x\" == c+foo;\n"
               "}", "test.c");
-        ASSERT_EQUALS("[test.c:2]: (warning) String literal compared with variable 'c'. Did you intend to use strcmp() instead?\n", errout.str());
+        ASSERT_EQUALS("[test.c:2]: (warning) String literal compared with variable 'c+foo'. Did you intend to use strcmp() instead?\n", errout.str());
 
         check("bool foo(Foo c) {\n"
               "    return \"x\" == c.foo;\n"
@@ -424,6 +424,21 @@ class TestString : public TestFixture {
               "}");
         ASSERT_EQUALS("", errout.str());
 
+        check("bool foo(char* c) {\n"
+              "    return c[0] == '\\0';\n"
+              "}");
+        ASSERT_EQUALS("", errout.str());
+
+        check("bool foo(char** c) {\n"
+              "    return c[0] == '\\0';\n"
+              "}");
+        ASSERT_EQUALS("[test.cpp:2]: (warning) Char literal compared with pointer 'c[0]'. Did you intend to dereference it?\n", errout.str());
+
+        check("bool foo(char** c) {\n"
+              "    return *c == '\\0';\n"
+              "}");
+        ASSERT_EQUALS("[test.cpp:2]: (warning) Char literal compared with pointer '*c'. Did you intend to dereference it?\n", errout.str());
+
         check("bool foo(char c) {\n"
               "    return c == 0;\n"
               "}");