/* * Cppcheck - A tool for static C/C++ code analysis * Copyright (C) 2007-2015 Daniel Marjamäki and Cppcheck team. * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see . */ //--------------------------------------------------------------------------- // Check for condition mismatches //--------------------------------------------------------------------------- #include "checkcondition.h" #include "checkother.h" #include "symboldatabase.h" #include //--------------------------------------------------------------------------- // Register this check class (by creating a static instance of it) namespace { CheckCondition instance; } void CheckCondition::assignIf() { if (!_settings->isEnabled("style")) return; for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next()) { if (tok->str() != "=") continue; if (Token::Match(tok->tokAt(-2), "[;{}] %var% =")) { const Variable *var = tok->previous()->variable(); if (var == 0) continue; char bitop = '\0'; MathLib::bigint num = 0; if (Token::Match(tok->next(), "%num% [&|]")) { bitop = tok->strAt(2).at(0); num = MathLib::toLongNumber(tok->next()->str()); } else { const Token *endToken = Token::findsimplematch(tok, ";"); // Casting address if (endToken && Token::Match(endToken->tokAt(-4), "* ) & %any% ;")) endToken = nullptr; if (endToken && Token::Match(endToken->tokAt(-2), "[&|] %num% ;")) { bitop = endToken->strAt(-2).at(0); num = MathLib::toLongNumber(endToken->previous()->str()); } } if (bitop == '\0') continue; if (num < 0 && bitop == '|') continue; assignIfParseScope(tok, tok->tokAt(4), var->declarationId(), var->isLocal(), bitop, num); } } } /** parse scopes recursively */ bool CheckCondition::assignIfParseScope(const Token * const assignTok, const Token * const startTok, const unsigned int varid, const bool islocal, const char bitop, const MathLib::bigint num) { bool ret = false; for (const Token *tok2 = startTok; tok2; tok2 = tok2->next()) { if ((bitop == '&') && Token::Match(tok2->tokAt(2), "%varid% %cop% %num% ;", varid) && tok2->strAt(3) == std::string(1U, bitop)) { const MathLib::bigint num2 = MathLib::toLongNumber(tok2->strAt(4)); if (0 == (num & num2)) mismatchingBitAndError(assignTok, num, tok2, num2); } if (Token::Match(tok2, "%varid% =", varid)) { return true; } if (Token::Match(tok2, "++|-- %varid%", varid) || Token::Match(tok2, "%varid% ++|--", varid)) return true; if (Token::Match(tok2, "[(,] &| %varid% [,)]", varid)) { unsigned int argumentNumber = 0; const Token *ftok; for (ftok = tok2; ftok && ftok->str() != "("; ftok = ftok->previous()) { if (ftok->str() == ")") ftok = ftok->link(); else if (ftok->str() == ",") argumentNumber++; } ftok = ftok ? ftok->previous() : nullptr; if (!(ftok && ftok->function())) return true; const Variable *par = ftok->function()->getArgumentVar(argumentNumber); if (par == nullptr || par->isReference() || par->isPointer()) return true; } if (tok2->str() == "}") return false; if (Token::Match(tok2, "break|continue|return")) ret = true; if (ret && tok2->str() == ";") return false; if (!islocal && Token::Match(tok2, "%name% (") && !Token::simpleMatch(tok2->next()->link(), ") {")) return true; if (Token::Match(tok2, "if|while (")) { if (!islocal && tok2->str() == "while") continue; // parse condition const Token * const end = tok2->next()->link(); for (; tok2 != end; tok2 = tok2->next()) { if (Token::Match(tok2, "[(,] &| %varid% [,)]", varid)) { return true; } if (Token::Match(tok2,"&&|%oror%|( %varid% %any% %num% &&|%oror%|)", varid)) { const Token *vartok = tok2->next(); const std::string& op(vartok->strAt(1)); const MathLib::bigint num2 = MathLib::toLongNumber(vartok->strAt(2)); const std::string condition(vartok->str() + op + vartok->strAt(2)); if (op == "==" && (num & num2) != ((bitop=='&') ? num2 : num)) assignIfError(assignTok, tok2, condition, false); else if (op == "!=" && (num & num2) != ((bitop=='&') ? num2 : num)) assignIfError(assignTok, tok2, condition, true); } } bool ret1 = assignIfParseScope(assignTok, end->tokAt(2), varid, islocal, bitop, num); bool ret2 = false; if (Token::simpleMatch(end->next()->link(), "} else {")) ret2 = assignIfParseScope(assignTok, end->next()->link()->tokAt(3), varid, islocal, bitop, num); if (ret1 || ret2) return true; } } return false; } void CheckCondition::assignIfError(const Token *tok1, const Token *tok2, const std::string &condition, bool result) { std::list locations; locations.push_back(tok1); locations.push_back(tok2); reportError(locations, Severity::style, "assignIfError", "Mismatching assignment and comparison, comparison '" + condition + "' is always " + std::string(result ? "true" : "false") + "."); } void CheckCondition::mismatchingBitAndError(const Token *tok1, const MathLib::bigint num1, const Token *tok2, const MathLib::bigint num2) { std::list locations; locations.push_back(tok1); locations.push_back(tok2); std::ostringstream msg; msg << "Mismatching bitmasks. Result is always 0 (" << "X = Y & 0x" << std::hex << num1 << "; Z = X & 0x" << std::hex << num2 << "; => Z=0)."; reportError(locations, Severity::style, "mismatchingBitAnd", msg.str()); } static void getnumchildren(const Token *tok, std::list &numchildren) { if (tok->astOperand1() && tok->astOperand1()->isNumber()) numchildren.push_back(MathLib::toLongNumber(tok->astOperand1()->str())); else if (tok->astOperand1() && tok->str() == tok->astOperand1()->str()) getnumchildren(tok->astOperand1(), numchildren); if (tok->astOperand2() && tok->astOperand2()->isNumber()) numchildren.push_back(MathLib::toLongNumber(tok->astOperand2()->str())); else if (tok->astOperand2() && tok->str() == tok->astOperand2()->str()) getnumchildren(tok->astOperand2(), numchildren); } void CheckCondition::checkBadBitmaskCheck() { if (!_settings->isEnabled("warning")) return; for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next()) { if (tok->str() == "|" && tok->astOperand1() && tok->astOperand2() && tok->astParent()) { const Token* parent = tok->astParent(); const bool isBoolean = Token::Match(parent, "&&|%oror%") || (parent->str() == "?" && parent->astOperand1() == tok) || (parent->str() == "=" && parent->astOperand2() == tok && parent->astOperand1() && parent->astOperand1()->variable() && parent->astOperand1()->variable()->typeStartToken()->str() == "bool") || (parent->str() == "(" && Token::Match(parent->astOperand1(), "if|while")); const bool isTrue = (tok->astOperand1()->values.size() == 1 && tok->astOperand1()->values.front().intvalue != 0 && !tok->astOperand1()->values.front().conditional) || (tok->astOperand2()->values.size() == 1 && tok->astOperand2()->values.front().intvalue != 0 && !tok->astOperand2()->values.front().conditional); if (isBoolean && isTrue) badBitmaskCheckError(tok); } } } void CheckCondition::badBitmaskCheckError(const Token *tok) { reportError(tok, Severity::warning, "badBitmaskCheck", "Result of operator '|' is always true if one operand is non-zero. Did you intend to use '&'?"); } void CheckCondition::comparison() { if (!_settings->isEnabled("style")) return; // Experimental code based on AST for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next()) { if (Token::Match(tok, "==|!=")) { const Token *expr1 = tok->astOperand1(); const Token *expr2 = tok->astOperand2(); if (!expr1 || !expr2) continue; if (expr1->isNumber()) std::swap(expr1,expr2); if (!expr2->isNumber()) continue; const MathLib::bigint num2 = MathLib::toLongNumber(expr2->str()); if (num2 < 0) continue; if (!Token::Match(expr1,"[&|]")) continue; std::list numbers; getnumchildren(expr1, numbers); for (std::list::const_iterator num = numbers.begin(); num != numbers.end(); ++num) { const MathLib::bigint num1 = *num; if (num1 < 0) continue; if ((expr1->str() == "&" && (num1 & num2) != num2) || (expr1->str() == "|" && (num1 | num2) != num2)) { const std::string& op(tok->str()); comparisonError(expr1, expr1->str(), num1, op, num2, op=="==" ? false : true); } } } } } void CheckCondition::comparisonError(const Token *tok, const std::string &bitop, MathLib::bigint value1, const std::string &op, MathLib::bigint value2, bool result) { std::ostringstream expression; expression << std::hex << "(X " << bitop << " 0x" << value1 << ") " << op << " 0x" << value2; const std::string errmsg("Expression '" + expression.str() + "' is always " + (result?"true":"false") + ".\n" "The expression '" + expression.str() + "' is always " + (result?"true":"false") + ". Check carefully constants and operators used, these errors might be hard to " "spot sometimes. In case of complex expression it might help to split it to " "separate expressions."); reportError(tok, Severity::style, "comparisonError", errmsg); } static bool isOverlappingCond(const Token * const cond1, const Token * const cond2, const std::set &constFunctions) { if (!cond1 || !cond2) return false; // same expressions if (isSameExpression(cond1,cond2,constFunctions)) return true; // bitwise overlap for example 'x&7' and 'x==1' if (cond1->str() == "&" && cond1->astOperand1() && cond2->astOperand2()) { const Token *expr1 = cond1->astOperand1(); const Token *num1 = cond1->astOperand2(); if (!num1) // unary operator& return false; if (!num1->isNumber()) std::swap(expr1,num1); if (!num1->isNumber() || MathLib::isNegative(num1->str())) return false; if (!Token::Match(cond2, "&|==") || !cond2->astOperand1() || !cond2->astOperand2()) return false; const Token *expr2 = cond2->astOperand1(); const Token *num2 = cond2->astOperand2(); if (!num2->isNumber()) std::swap(expr2,num2); if (!num2->isNumber() || MathLib::isNegative(num2->str())) return false; if (!isSameExpression(expr1,expr2,constFunctions)) return false; const MathLib::bigint value1 = MathLib::toLongNumber(num1->str()); const MathLib::bigint value2 = MathLib::toLongNumber(num2->str()); return ((value1 & value2) > 0); } return false; } void CheckCondition::multiCondition() { if (!_settings->isEnabled("style")) return; const SymbolDatabase* const symbolDatabase = _tokenizer->getSymbolDatabase(); for (std::list::const_iterator i = symbolDatabase->scopeList.begin(); i != symbolDatabase->scopeList.end(); ++i) { if (i->type != Scope::eIf) continue; const Token * const cond1 = i->classDef->next()->astOperand2(); const Token * tok2 = i->classDef->next(); for (;;) { tok2 = tok2->link(); if (!Token::simpleMatch(tok2, ") {")) break; tok2 = tok2->linkAt(1); if (!Token::simpleMatch(tok2, "} else { if (")) break; tok2 = tok2->tokAt(4); if (isOverlappingCond(cond1, tok2->astOperand2(), _settings->library.functionpure)) multiConditionError(tok2, cond1->linenr()); } } } void CheckCondition::multiConditionError(const Token *tok, unsigned int line1) { std::ostringstream errmsg; errmsg << "Expression is always false because 'else if' condition matches previous condition at line " << line1 << "."; reportError(tok, Severity::style, "multiCondition", errmsg.str()); } //--------------------------------------------------------------------------- // Detect oppositing inner and outer conditions //--------------------------------------------------------------------------- /** * Are two conditions opposite * @param isNot do you want to know if cond1 is !cond2 or if cond1 and cond2 are non-overlapping. true: cond1==!cond2 false: cond1==true => cond2==false * @param cond1 condition1 * @param cond2 condition2 */ static bool isOppositeCond(bool isNot, const Token * const cond1, const Token * const cond2, const std::set &constFunctions) { if (!cond1 || !cond2) return false; if (cond1->str() == "!") return isSameExpression(cond1->astOperand1(), cond2, constFunctions); if (cond2->str() == "!") return isSameExpression(cond1, cond2->astOperand1(), constFunctions); if (!cond1->isComparisonOp() || !cond2->isComparisonOp()) return false; const std::string &comp1 = cond1->str(); // condition found .. get comparator std::string comp2; if (isSameExpression(cond1->astOperand1(), cond2->astOperand1(), constFunctions) && isSameExpression(cond1->astOperand2(), cond2->astOperand2(), constFunctions)) { comp2 = cond2->str(); } else if (isSameExpression(cond1->astOperand1(), cond2->astOperand2(), constFunctions) && isSameExpression(cond1->astOperand2(), cond2->astOperand1(), constFunctions)) { comp2 = cond2->str(); if (comp2[0] == '>') comp2[0] = '<'; else if (comp2[0] == '<') comp2[0] = '>'; } // is condition opposite? return ((comp1 == "==" && comp2 == "!=") || (comp1 == "!=" && comp2 == "==") || (comp1 == "<" && comp2 == ">=") || (comp1 == "<=" && comp2 == ">") || (comp1 == ">" && comp2 == "<=") || (comp1 == ">=" && comp2 == "<") || (!isNot && ((comp1 == "<" && comp2 == ">") || (comp1 == ">" && comp2 == "<")))); } void CheckCondition::oppositeInnerCondition() { if (!_settings->isEnabled("warning")) return; const SymbolDatabase *symbolDatabase = _tokenizer->getSymbolDatabase(); for (std::list::const_iterator scope = symbolDatabase->scopeList.begin(); scope != symbolDatabase->scopeList.end(); ++scope) { if (scope->type != Scope::eIf) continue; if (!Token::simpleMatch(scope->classDef->linkAt(1), ") {")) continue; bool nonlocal = false; // nonlocal variable used in condition std::set vars; // variables used in condition for (const Token *cond = scope->classDef->linkAt(1); cond != scope->classDef; cond = cond->previous()) { if (cond->varId()) { vars.insert(cond->varId()); const Variable *var = cond->variable(); nonlocal |= (var && (!var->isLocal() || var->isStatic()) && !var->isArgument()); // TODO: if var is pointer check what it points at nonlocal |= (var && (var->isPointer() || var->isReference())); } else if (cond->isName()) { // varid is 0. this is possibly a nonlocal variable.. nonlocal |= Token::Match(cond->astParent(), "%cop%|("); } } // parse until inner condition is reached.. const Token *ifToken = nullptr; for (const Token *tok = scope->classStart; tok && tok != scope->classEnd; tok = tok->next()) { if (Token::simpleMatch(tok, "if (")) { ifToken = tok; break; } if (Token::Match(tok, "%type% (") && nonlocal) // function call -> bailout if there are nonlocal variables break; else if ((tok->varId() && vars.find(tok->varId()) != vars.end()) || (!tok->varId() && nonlocal)) { if (Token::Match(tok, "%name% ++|--|=")) break; if (Token::Match(tok, "%name% [")) { const Token *tok2 = tok->linkAt(1); while (Token::simpleMatch(tok2, "] [")) tok2 = tok2->linkAt(1); if (Token::simpleMatch(tok2, "] =")) break; } if (Token::Match(tok->previous(), "++|--|& %name%")) break; if (tok->variable() && Token::Match(tok, "%name% . %name% (") && !tok->variable()->isConst()) { const Function* function = tok->tokAt(2)->function(); if (!function || !function->isConst()) break; } if (Token::Match(tok->previous(), "[(,] %name% [,)]")) { // is variable unchanged? default is false.. bool unchanged = false; // locate start parentheses in function call.. unsigned int argumentNumber = 0; const Token *start = tok->previous(); while (start && start->str() == ",") { start = start->astParent(); ++argumentNumber; } start = start ? start->previous() : nullptr; if (start && start->function()) { const Variable *arg = start->function()->getArgumentVar(argumentNumber); if (arg && !arg->isPointer() && !arg->isReference()) unchanged = true; } if (!unchanged) break; } } } if (!ifToken) continue; // Condition.. const Token *cond1 = scope->classDef->next()->astOperand2(); const Token *cond2 = ifToken->next()->astOperand2(); if (isOppositeCond(false, cond1, cond2, _settings->library.functionpure)) oppositeInnerConditionError(scope->classDef, cond2); } } void CheckCondition::oppositeInnerConditionError(const Token *tok1, const Token* tok2) { std::list callstack; callstack.push_back(tok1); callstack.push_back(tok2); reportError(callstack, Severity::warning, "oppositeInnerCondition", "Opposite conditions in nested 'if' blocks lead to a dead code block."); } //--------------------------------------------------------------------------- // if ((x != 1) || (x != 3)) // expression always true // if ((x == 1) && (x == 3)) // expression always false // if ((x < 1) && (x > 3)) // expression always false // if ((x > 3) || (x < 10)) // expression always true // if ((x > 5) && (x != 1)) // second comparison always true // // Check for suspect logic for an expression consisting of 2 comparison // expressions with a shared variable and constants and a logical operator // between them. // // Suggest a different logical operator when the logical operator between // the comparisons is probably wrong. // // Inform that second comparison is always true when first comparison is true. //--------------------------------------------------------------------------- static std::string invertOperatorForOperandSwap(std::string s) { if (s[0] == '<') s[0] = '>'; else if (s[0] == '>') s[0] = '<'; return s; } template static bool checkIntRelation(const std::string &op, const T value1, const T value2) { return (op == "==" && value1 == value2) || (op == "!=" && value1 != value2) || (op == ">" && value1 > value2) || (op == ">=" && value1 >= value2) || (op == "<" && value1 < value2) || (op == "<=" && value1 <= value2); } static bool checkFloatRelation(const std::string &op, const double value1, const double value2) { return (op == ">" && value1 > value2) || (op == ">=" && value1 >= value2) || (op == "<" && value1 < value2) || (op == "<=" && value1 <= value2); } template T getvalue3(const T value1, const T value2) { if (std::numeric_limits::is_integer) { const T min = std::min(value1, value2); if (min== std::numeric_limits::max()) return min; else return min+1; // see #5895 } return (value1 + value2) / (T)2; } template<> double getvalue3(const double value1, const double value2) { return (value1 + value2) / 2.0f; } template static inline T getvalue(const int test, const T value1, const T value2) { // test: // 1 => return value that is less than both value1 and value2 // 2 => return value1 // 3 => return value that is between value1 and value2 // 4 => return value2 // 5 => return value that is larger than both value1 and value2 switch (test) { case 1: { const T ret = std::min(value1, value2); if ((ret - (T)1) < ret) return ret - (T)1; else if ((ret / (T)2) < ret) return ret / (T)2; else if ((ret * (T)2) < ret) return ret * (T)2; return ret; } case 2: return value1; case 3: return getvalue3(value1, value2); case 4: return value2; case 5: { const T ret = std::max(value1, value2); if ((ret + (T)1) > ret) return ret + (T)1; else if ((ret / (T)2) > ret) return ret / (T)2; else if ((ret * (T)2) > ret) return ret * (T)2; return ret; } }; return 0; } void CheckCondition::checkIncorrectLogicOperator() { const bool printStyle = _settings->isEnabled("style"); const bool printWarning = _settings->isEnabled("warning"); if (!printWarning && !printStyle) return; const SymbolDatabase *symbolDatabase = _tokenizer->getSymbolDatabase(); const std::size_t functions = symbolDatabase->functionScopes.size(); for (std::size_t ii = 0; ii < functions; ++ii) { const Scope * scope = symbolDatabase->functionScopes[ii]; for (const Token* tok = scope->classStart->next(); tok != scope->classEnd; tok = tok->next()) { // Opposite comparisons if (Token::Match(tok, "%oror%|&&") && tok->astOperand1() && tok->astOperand2() && (tok->astOperand1()->isName() || tok->astOperand2()->isName()) && isOppositeCond(true, tok->astOperand1(), tok->astOperand2(), _settings->library.functionpure)) { const bool alwaysTrue(tok->str() == "||"); incorrectLogicOperatorError(tok, tok->expressionString(), alwaysTrue); } else if (Token::Match(tok, "&&|%oror%")) { if (printStyle && (tok->str() == "||") && tok->astOperand1() && tok->astOperand2() && tok->astOperand2()->str() == "&&") { const Token* tok2 = tok->astOperand2()->astOperand1(); if (isOppositeCond(true, tok->astOperand1(), tok2, _settings->library.functionpure)) { redundantConditionError(tok, tok2->expressionString() + ". 'A && (!A || B)' is equivalent to 'A || B'"); } } // Comparison #1 (LHS) const Token *comp1 = tok->astOperand1(); if (comp1 && comp1->str() == tok->str()) comp1 = comp1->astOperand2(); // Comparison #2 (RHS) const Token *comp2 = tok->astOperand2(); if (!comp1 || !comp1->isComparisonOp() || !comp1->astOperand1() || !comp1->astOperand2()) continue; if (!comp2 || !comp2->isComparisonOp() || !comp2->astOperand1() || !comp2->astOperand2()) continue; std::string op1, value1; const Token *expr1; if (comp1->astOperand1()->isLiteral()) { op1 = invertOperatorForOperandSwap(comp1->str()); value1 = comp1->astOperand1()->str(); expr1 = comp1->astOperand2(); } else if (comp1->astOperand2()->isLiteral()) { op1 = comp1->str(); value1 = comp1->astOperand2()->str(); expr1 = comp1->astOperand1(); } else { continue; } std::string op2, value2; const Token *expr2; if (comp2->astOperand1()->isLiteral()) { op2 = invertOperatorForOperandSwap(comp2->str()); value2 = comp2->astOperand1()->str(); expr2 = comp2->astOperand2(); } else if (comp2->astOperand2()->isLiteral()) { op2 = comp2->str(); value2 = comp2->astOperand2()->str(); expr2 = comp2->astOperand1(); } else { continue; } // Only float and int values are currently handled if (!MathLib::isInt(value1) && !MathLib::isFloat(value1)) continue; if (!MathLib::isInt(value2) && !MathLib::isFloat(value2)) continue; if (isSameExpression(comp1, comp2, _settings->library.functionpure)) continue; // same expressions => only report that there are same expressions if (!isSameExpression(expr1, expr2, _settings->library.functionpure)) continue; const bool isfloat = astIsFloat(expr1, true) || MathLib::isFloat(value1) || astIsFloat(expr2, true) || MathLib::isFloat(value2); // don't check floating point equality comparisons. that is bad // and deserves different warnings. if (isfloat && (op1 == "==" || op1 == "!=" || op2 == "==" || op2 == "!=")) continue; const double d1 = (isfloat) ? MathLib::toDoubleNumber(value1) : 0; const double d2 = (isfloat) ? MathLib::toDoubleNumber(value2) : 0; const MathLib::bigint i1 = (isfloat) ? 0 : MathLib::toLongNumber(value1); const MathLib::bigint i2 = (isfloat) ? 0 : MathLib::toLongNumber(value2); const bool useUnsignedInt = (std::numeric_limits::max()==i1)||(std::numeric_limits::max()==i2); const MathLib::biguint u1 = (useUnsignedInt) ? MathLib::toLongNumber(value1) : 0; const MathLib::biguint u2 = (useUnsignedInt) ? MathLib::toLongNumber(value2) : 0; // evaluate if expression is always true/false bool alwaysTrue = true, alwaysFalse = true; bool firstTrue = true, secondTrue = true; for (int test = 1; test <= 5; ++test) { // test: // 1 => testvalue is less than both value1 and value2 // 2 => testvalue is value1 // 3 => testvalue is between value1 and value2 // 4 => testvalue value2 // 5 => testvalue is larger than both value1 and value2 bool result1, result2; if (isfloat) { const double testvalue = getvalue(test, d1, d2); result1 = checkFloatRelation(op1, testvalue, d1); result2 = checkFloatRelation(op2, testvalue, d2); } else if (useUnsignedInt) { const MathLib::biguint testvalue = getvalue(test, u1, u2); result1 = checkIntRelation(op1, testvalue, u1); result2 = checkIntRelation(op2, testvalue, u2); } else { const MathLib::bigint testvalue = getvalue(test, i1, i2); result1 = checkIntRelation(op1, testvalue, i1); result2 = checkIntRelation(op2, testvalue, i2); } if (tok->str() == "&&") { alwaysTrue &= (result1 && result2); alwaysFalse &= !(result1 && result2); } else { alwaysTrue &= (result1 || result2); alwaysFalse &= !(result1 || result2); } firstTrue &= !(!result1 && result2); secondTrue &= !(result1 && !result2); } const std::string cond1str = (expr1->isName() ? expr1->str() : "EXPR") + " " + op1 + " " + value1; const std::string cond2str = (expr2->isName() ? expr2->str() : "EXPR") + " " + op2 + " " + value2; if (printWarning && (alwaysTrue || alwaysFalse)) { const std::string text = cond1str + " " + tok->str() + " " + cond2str; incorrectLogicOperatorError(tok, text, alwaysTrue); } else if (printStyle && secondTrue) { const std::string text = "If " + cond1str + ", the comparison " + cond2str + " is always " + (secondTrue ? "true" : "false") + "."; redundantConditionError(tok, text); } else if (printStyle && firstTrue) { //const std::string text = "The comparison " + cond1str + " is always " + // (firstTrue ? "true" : "false") + " when " + // cond2str + "."; const std::string text = "If " + cond2str + ", the comparison " + cond1str + " is always " + (firstTrue ? "true" : "false") + "."; redundantConditionError(tok, text); } } } } } void CheckCondition::incorrectLogicOperatorError(const Token *tok, const std::string &condition, bool always) { if (always) reportError(tok, Severity::warning, "incorrectLogicOperator", "Logical disjunction always evaluates to true: " + condition + ".\n" "Logical disjunction always evaluates to true: " + condition + ". " "Are these conditions necessary? Did you intend to use && instead? Are the numbers correct? Are you comparing the correct variables?"); else reportError(tok, Severity::warning, "incorrectLogicOperator", "Logical conjunction always evaluates to false: " + condition + ".\n" "Logical conjunction always evaluates to false: " + condition + ". " "Are these conditions necessary? Did you intend to use || instead? Are the numbers correct? Are you comparing the correct variables?"); } void CheckCondition::redundantConditionError(const Token *tok, const std::string &text) { reportError(tok, Severity::style, "redundantCondition", "Redundant condition: " + text); } //----------------------------------------------------------------------------- // Detect "(var % val1) > val2" where val2 is >= val1. //----------------------------------------------------------------------------- void CheckCondition::checkModuloAlwaysTrueFalse() { if (!_settings->isEnabled("warning")) return; const SymbolDatabase *symbolDatabase = _tokenizer->getSymbolDatabase(); const std::size_t functions = symbolDatabase->functionScopes.size(); for (std::size_t i = 0; i < functions; ++i) { const Scope * scope = symbolDatabase->functionScopes[i]; for (const Token* tok = scope->classStart->next(); tok != scope->classEnd; tok = tok->next()) { if (!tok->isComparisonOp()) continue; const Token *num, *modulo; if (Token::simpleMatch(tok->astOperand1(), "%") && Token::Match(tok->astOperand2(), "%num%")) { modulo = tok->astOperand1(); num = tok->astOperand2(); } else if (Token::Match(tok->astOperand1(), "%num%") && Token::simpleMatch(tok->astOperand2(), "%")) { num = tok->astOperand1(); modulo = tok->astOperand2(); } else { continue; } if (Token::Match(modulo->astOperand2(), "%num%") && MathLib::isLessEqual(modulo->astOperand2()->str(), num->str())) moduloAlwaysTrueFalseError(tok, modulo->astOperand2()->str()); } } } void CheckCondition::moduloAlwaysTrueFalseError(const Token* tok, const std::string& maxVal) { reportError(tok, Severity::warning, "moduloAlwaysTrueFalse", "Comparison of modulo result is predetermined, because it is always less than " + maxVal + "."); } //--------------------------------------------------------------------------- // Clarify condition '(x = a < 0)' into '((x = a) < 0)' or '(x = (a < 0))' // Clarify condition '(a & b == c)' into '((a & b) == c)' or '(a & (b == c))' //--------------------------------------------------------------------------- void CheckCondition::clarifyCondition() { if (!_settings->isEnabled("style")) return; const bool isC = _tokenizer->isC(); const SymbolDatabase *symbolDatabase = _tokenizer->getSymbolDatabase(); const std::size_t functions = symbolDatabase->functionScopes.size(); for (std::size_t i = 0; i < functions; ++i) { const Scope * scope = symbolDatabase->functionScopes[i]; for (const Token* tok = scope->classStart->next(); tok != scope->classEnd; tok = tok->next()) { if (Token::Match(tok, "( %name% [=&|^]")) { for (const Token *tok2 = tok->tokAt(3); tok2; tok2 = tok2->next()) { if (tok2->str() == "(" || tok2->str() == "[") tok2 = tok2->link(); else if (tok2->type() == Token::eComparisonOp) { // This might be a template if (!isC && tok2->link()) break; if (Token::simpleMatch(tok2->astParent(), "?")) break; clarifyConditionError(tok, tok->strAt(2) == "=", false); break; } else if (!tok2->isName() && !tok2->isNumber() && tok2->str() != ".") break; } } } } // using boolean result in bitwise operation ! x [&|^] for (std::size_t i = 0; i < functions; ++i) { const Scope * scope = symbolDatabase->functionScopes[i]; for (const Token* tok = scope->classStart->next(); tok != scope->classEnd; tok = tok->next()) { if (Token::Match(tok, "%comp%|!")) { if (tok->link()) // don't write false positives when templates are used continue; const Token *tok2 = tok->next(); // Todo: There are false positives if '(' if encountered. It // is assumed there is something like '(char *)&..' and therefore // it bails out. if (Token::Match(tok2, "(|&")) continue; while (tok2 && (tok2->isName() || tok2->isNumber() || Token::Match(tok2, ".|(|["))) { if (Token::Match(tok2, "(|[")) tok2 = tok2->link(); tok2 = tok2->next(); } if (Token::Match(tok2, "[&|^]")) { // don't write false positives when templates are used if (Token::Match(tok2, "&|* ,|>") || Token::simpleMatch(tok2->previous(), "const &")) continue; // #3609 - CWinTraits::.. if (!isC && Token::Match(tok->previous(), "%name% <")) { const Token *tok3 = tok2; while (Token::Match(tok3, "[&|^] %name%")) tok3 = tok3->tokAt(2); if (Token::Match(tok3, ",|>")) continue; } clarifyConditionError(tok, false, true); } } } } } void CheckCondition::clarifyConditionError(const Token *tok, bool assign, bool boolop) { std::string errmsg; if (assign) errmsg = "Suspicious condition (assignment + comparison); Clarify expression with parentheses."; else if (boolop) errmsg = "Boolean result is used in bitwise operation. Clarify expression with parentheses.\n" "Suspicious expression. Boolean result is used in bitwise operation. The operator '!' " "and the comparison operators have higher precedence than bitwise operators. " "It is recommended that the expression is clarified with parentheses."; else errmsg = "Suspicious condition (bitwise operator + comparison); Clarify expression with parentheses.\n" "Suspicious condition. Comparison operators have higher precedence than bitwise operators. " "Please clarify the condition with parentheses."; reportError(tok, Severity::style, "clarifyCondition", errmsg); }