cppcheck/lib/checkassert.cpp

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/*
* Cppcheck - A tool for static C/C++ code analysis
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* Copyright (C) 2007-2014 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 <http://www.gnu.org/licenses/>.
*/
//---------------------------------------------------------------------------
// You should not write statements with side effects in assert()
//---------------------------------------------------------------------------
#include "checkassert.h"
#include "symboldatabase.h"
//---------------------------------------------------------------------------
// Register this check class (by creating a static instance of it)
namespace {
CheckAssert instance;
}
void CheckAssert::assertWithSideEffects()
{
if (!_settings->isEnabled("warning"))
return;
const Token *tok = findAssertPattern(_tokenizer->tokens());
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const Token *endTok = tok ? tok->next()->link() : nullptr;
while (tok && endTok) {
for (const Token* tmp = tok->tokAt(1); tmp != endTok; tmp = tmp->next()) {
checkVariableAssignment(tmp, true);
if (tmp->isName() && tmp->type() == Token::eFunction) {
const Function* f = tmp->function();
if (f->argCount() == 0 && f->isConst) continue;
// functions with non-const references
else if (f->argCount() != 0) {
for (std::list<Variable>::const_iterator it = f->argumentList.begin(); it != f->argumentList.end(); ++it) {
if (it->isConst() || it->isLocal()) continue;
else if (it->isReference()) {
const Token* next = it->nameToken()->next();
bool isAssigned = checkVariableAssignment(next, false);
if (isAssigned)
sideEffectInAssertError(tmp, f->name());
continue;
}
}
}
// variables in function scope
const Scope* scope = f->functionScope;
if (!scope) continue;
for (const Token *tok2 = scope->classStart; tok2 != scope->classEnd; tok2 = tok2->next()) {
if (tok2->type() != Token::eAssignmentOp && tok2->type() != Token::eIncDecOp) continue;
const Variable* var = tok2->previous()->variable();
if (!var || var->isLocal()) continue;
if (var->isArgument() &&
(var->isConst() || (!var->isReference() && !var->isPointer())))
// see ticket #4937. Assigning function arguments not passed by reference is ok.
continue;
std::vector<const Token*> returnTokens; // find all return statements
for (const Token *rt = scope->classStart; rt != scope->classEnd; rt = rt->next()) {
if (!Token::Match(rt, "return %any%")) continue;
returnTokens.push_back(rt);
}
bool noReturnInScope = true;
for (std::vector<const Token*>::iterator rt = returnTokens.begin(); rt != returnTokens.end(); ++rt) {
noReturnInScope &= !inSameScope(*rt, tok2);
}
if (noReturnInScope) continue;
bool isAssigned = checkVariableAssignment(tok2, false);
if (isAssigned)
sideEffectInAssertError(tmp, f->name());
}
}
}
tok = findAssertPattern(endTok->next());
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endTok = tok ? tok->next()->link() : nullptr;
}
}
//---------------------------------------------------------------------------
void CheckAssert::sideEffectInAssertError(const Token *tok, const std::string& functionName)
{
reportError(tok, Severity::warning,
"assertWithSideEffect", "Assert statement calls a function which may have desired side effects: '" + functionName + "'.\n"
"Non-pure function: '" + functionName + "' 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.");
}
void CheckAssert::assignmentInAssertError(const Token *tok, const std::string& varname)
{
reportError(tok, Severity::warning,
"assignmentInAssert", "Assert statement modifies '" + varname + "'.\n"
"Variable '" + varname + "' is modified insert 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.");
}
// checks if side effects happen on the variable prior to tmp
bool CheckAssert::checkVariableAssignment(const Token* assignTok, bool reportErr /*= true*/)
{
const Variable* v = assignTok->previous()->variable();
if (!v) return false;
// assignment
if (assignTok->isAssignmentOp() || assignTok->type() == Token::eIncDecOp) {
if (v->isConst()) return false;
if (reportErr) // report as variable assignment error
assignmentInAssertError(assignTok, v->name());
return true;
}
return false;
// TODO: function calls on v
}
const Token* CheckAssert::findAssertPattern(const Token* start)
{
return Token::findmatch(start, "assert ( %any%");
}
bool CheckAssert::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();
}