Partial fix for #14911 FN knownConditionTrueFalse for number literals (regression) (cppcheck-opensource#8737)

Co-authored-by: chrchr-github <noreply@github.com>

Author: chrchr-github

lib/checkcondition.cpp

@@ -1575,10 +1575,19 @@ void CheckConditionImpl::alwaysTrueFalse()
                 continue;
             if (Token::simpleMatch(tok->astParent(), "return") && Token::Match(tok, ".|%var%"))
                 continue;
-            if (Token::Match(tok, "%num%|%bool%|%char%"))
-                continue;
-            if (Token::Match(tok, "! %num%|%bool%|%char%"))
-                continue;
+            bool warnForNumber = false;
+            if (Token::Match(tok, "%num%|%bool%|%char%")) {
+                const bool isZeroOrOne = (tok->getKnownIntValue() >> 1) == 0;
+                warnForNumber = !isZeroOrOne && tok->tokType() == Token::eNumber && tok->astParent() == condition->astParent();
+                if (!warnForNumber)
+                    continue;
+            }
+            if (Token::Match(tok, "! %num%|%bool%|%char%")) {
+                const bool isZeroOrOne = tok->next()->hasKnownIntValue() && (tok->next()->getKnownIntValue() >> 1) == 0;
+                warnForNumber = !isZeroOrOne && tok->next()->tokType() == Token::eNumber && tok->astParent() == condition->astParent();
+                if (!warnForNumber)
+                    continue;
+            }
             if (Token::Match(tok, "%oror%|&&")) {
                 bool bail = false;
                 for (const Token* op : { tok->astOperand1(), tok->astOperand2() }) {
@@ -1603,7 +1612,7 @@ void CheckConditionImpl::alwaysTrueFalse()
                                  true))
                 continue;
 
-            if (!pedantic && isConstVarExpression(tok, [](const Token* tok) {
+            if (!pedantic && !warnForNumber && isConstVarExpression(tok, [](const Token* tok) {
                 return Token::Match(tok, "[|(|&|+|-|*|/|%|^|>>|<<") && !Token::simpleMatch(tok, "( )");
             }))
                 continue;

test/testcondition.cpp

@@ -4949,6 +4949,28 @@ class TestCondition : public TestFixture {
               "    return x ? false : true;\n"
               "}\n");
         ASSERT_EQUALS("", errout_str());
+
+        check("void f() {\n"
+              "    if (42) {}\n"
+              "    if (42U) {}\n"
+              "    if (42L) {}\n"
+              "    if (42UL) {}\n"
+              "    if (42LL) {}\n"
+              "    if (042) {}\n"
+              "    if (0x42) {}\n"
+              "    if (0b101010) {}\n"
+              "    if (!42) {}\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:2:9]: (style) Condition '42' is always true [knownConditionTrueFalse]\n"
+                      "[test.cpp:3:9]: (style) Condition '42U' is always true [knownConditionTrueFalse]\n"
+                      "[test.cpp:4:9]: (style) Condition '42L' is always true [knownConditionTrueFalse]\n"
+                      "[test.cpp:5:9]: (style) Condition '42UL' is always true [knownConditionTrueFalse]\n"
+                      "[test.cpp:6:9]: (style) Condition '42LL' is always true [knownConditionTrueFalse]\n"
+                      "[test.cpp:7:9]: (style) Condition '042' is always true [knownConditionTrueFalse]\n"
+                      "[test.cpp:8:9]: (style) Condition '0x42' is always true [knownConditionTrueFalse]\n"
+                      "[test.cpp:9:9]: (style) Condition '0b101010' is always true [knownConditionTrueFalse]\n"
+                      "[test.cpp:10:9]: (style) Condition '!42' is always false [knownConditionTrueFalse]\n",
+                      errout_str());
     }
 
     void alwaysTrueSymbolic()