/*

* Cppcheck - A tool for static C/C++ code analysis

* Copyright (C) 2007-2026 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 <http://www.gnu.org/licenses/>.

*/

//---------------------------------------------------------------------------

// You should not write statements with side effects in assert()

//---------------------------------------------------------------------------

#include "checkassert.h"

#include "astutils.h"

#include "errortypes.h"

#include "library.h"

#include "settings.h"

#include "symboldatabase.h"

#include "token.h"

#include "tokenize.h"

#include "tokenlist.h"

#include <algorithm>

#include <utility>

//---------------------------------------------------------------------------

// CWE ids used

static const CWE CWE398(398U); // Indicator of Poor Code Quality

void CheckAssertImpl::assertWithSideEffects()

{

if (!mSettings.severity.isEnabled(Severity::warning))

return;

logChecker("CheckAssert::assertWithSideEffects"); // warning

for (const Token* tok = mTokenizer->list.front(); tok; tok = tok->next()) {

if (!Token::simpleMatch(tok, "assert ("))

continue;

const Token *endTok = tok->linkAt(1);

for (const Token* tmp = tok->next(); tmp != endTok; tmp = tmp->next()) {

if (Token::simpleMatch(tmp, "sizeof ("))

tmp = tmp->linkAt(1);

checkVariableAssignment(tmp, tok->scope());

if (tmp->tokType() != Token::eFunction) {

if (const Library::Function* f = mSettings.library.getFunction(tmp)) {

if (f->isconst || f->ispure)

continue;

if (Library::getContainerYield(tmp->next()) != Library::Container::Yield::NO_YIELD) // bailout, assume read access

continue;

if (std::any_of(f->argumentChecks.begin(), f->argumentChecks.end(), [](const std::pair<int, Library::ArgumentChecks>& ac) {

return ac.second.iteratorInfo.container > 0; // bailout, takes iterators -> assume read access

}))

continue;

if (tmp->str() == "get" && Token::simpleMatch(tmp->astParent(), ".") && astIsSmartPointer(tmp->astParent()->astOperand1()))

continue;

if (f->containerYield == Library::Container::Yield::START_ITERATOR || // bailout for std::begin/end/prev/next

f->containerYield == Library::Container::Yield::END_ITERATOR ||

f->containerYield == Library::Container::Yield::ITERATOR)

continue;

sideEffectInAssertError(tmp, mSettings.library.getFunctionName(tmp));

}

continue;

}

const Token* parent = tmp->astParent();

while (Token::Match(parent, ".|::"))

parent = parent->astParent();

if (!Token::simpleMatch(parent, "("))

continue;

const Function* f = tmp->function();

const Scope* scope = f->functionScope;

if (!scope) {

// guess that const method doesn't have side effects

if (f->nestedIn->isClassOrStruct() && !f->isConst() && !f->isStatic())

sideEffectInAssertError(tmp, f->name(), " If there are no side effects, consider declaring the method const."); // Non-const member function called, assume it has side effects

continue;

}

for (const Token *tok2 = scope->bodyStart; tok2 != scope->bodyEnd; tok2 = tok2->next()) {

if (!tok2->isAssignmentOp() && tok2->tokType() != Token::eIncDecOp)

continue;

const Variable* var = tok2->previous()->variable();

if (!var || var->isLocal() || (var->isArgument() && !var->isReference() && !var->isPointer()))

continue; // See ticket #4937. Assigning function arguments not passed by reference is ok.

if (var->isArgument() && var->isPointer() && tok2->strAt(-2) != "*")

continue; // Pointers need to be dereferenced, otherwise there is no error

bool noReturnInScope = true;

for (const Token *rt = scope->bodyStart; rt != scope->bodyEnd; rt = rt->next()) {

if (rt->str() != "return") continue; // find all return statements

if (inSameScope(rt, tok2)) {

noReturnInScope = false;

break;

}

}

if (noReturnInScope) continue;

sideEffectInAssertError(tmp, f->name());

break;

}

}

tok = endTok;

}

}

//---------------------------------------------------------------------------

void CheckAssertImpl::sideEffectInAssertError(const Token *tok, const std::string& functionName, const std::string &extra)

{

reportError(tok, Severity::warning,

"assertWithSideEffect",

"$symbol:" + functionName + "\n"

"Assert statement calls a function which may have desired side effects: '$symbol'." + extra + "\n"

"Non-pure function: '$symbol' is called inside assert statement. "

"Assert statements are removed from release builds so the code inside "

"assert statement is not executed. If the code is needed also in release "

"builds, this is a bug.", CWE398, Certainty::normal);

}

void CheckAssertImpl::assignmentInAssertError(const Token *tok, const std::string& varname)

{

reportError(tok, Severity::warning,

"assignmentInAssert",

"$symbol:" + varname + "\n"

"Assert statement modifies '$symbol'.\n"

"Variable '$symbol' is modified inside assert statement. "

"Assert statements are removed from release builds so the code inside "

"assert statement is not executed. If the code is needed also in release "

"builds, this is a bug.", CWE398, Certainty::normal);

}

// checks if side effects happen on the variable prior to tmp

void CheckAssertImpl::checkVariableAssignment(const Token* assignTok, const Scope *assertionScope)

{

if (!assignTok->isAssignmentOp() && assignTok->tokType() != Token::eIncDecOp)

return;

if (!assignTok->astOperand1())

return;

const Variable* var = assignTok->astOperand1()->variable();

if (!var)

return;

// Variable declared in inner scope in assert => don't warn

if (assertionScope != var->scope()) {

const Scope *s = var->scope();

while (s && s != assertionScope)

s = s->nestedIn;

if (s == assertionScope)

return;

}

// assignment

if (assignTok->isAssignmentOp() || assignTok->tokType() == Token::eIncDecOp) {

if (var->isConst()) {

return;

}

assignmentInAssertError(assignTok, var->name());

}

// TODO: function calls on var

}

bool CheckAssertImpl::inSameScope(const Token* returnTok, const Token* assignTok)

{

// TODO: even if a return is in the same scope, the assignment might not affect it.

return returnTok->scope() == assignTok->scope();

}

void CheckAssert::runChecks(const Tokenizer &tokenizer, ErrorLogger& errorLogger)

{

CheckAssertImpl checkAssert(&tokenizer, tokenizer.getSettings(), errorLogger);

checkAssert.assertWithSideEffects();

}

void CheckAssert::getErrorMessages(ErrorLogger& errorLogger, const Settings &settings) const

{

CheckAssertImpl c(nullptr, settings, errorLogger);

c.sideEffectInAssertError(nullptr, "function");

c.assignmentInAssertError(nullptr, "var");

}