walkero
/
cppcheck
1
0
Fork 0
Code Issues Pull Requests Projects Releases 1 Wiki Activity

Warn when shifting a negative value, it is UB. (#4931)

This commit is contained in:
Daniel Marjamäki 2015-11-29 16:28:55 +01:00
parent 8a9e068129
commit 4fa888ec44
3 changed files with 44 additions and 41 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

77
lib/checkother.cpp
View File

@ -2177,54 +2177,53 @@ void CheckOther::redundantCopyError(const Token *tok,const std::string& varname)
void CheckOther::checkNegativeBitwiseShift()
{
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->str() != "<<" && tok->str() != ">>")
for (const Token* tok = _tokenizer->tokens(); tok; tok = tok->next()) {
if (tok->str() != "<<" && tok->str() != ">>")
continue;
if (!tok->astOperand1() || !tok->astOperand2())
continue;
// don't warn if lhs is a class. this is an overloaded operator then
if (_tokenizer->isCPP()) {
const Token *rhs = tok->astOperand1();
while (Token::Match(rhs, "::|."))
rhs = rhs->astOperand2();
if (!rhs)
continue;
if (!tok->astOperand1() || !tok->astOperand2())
if (!rhs->isNumber() && !rhs->variable())
continue;
// don't warn if lhs is a class. this is an overloaded operator then
if (_tokenizer->isCPP()) {
const Token *rhs = tok->astOperand1();
while (Token::Match(rhs, "::|."))
rhs = rhs->astOperand2();
if (!rhs)
continue;
if (!rhs->isNumber() && !rhs->variable())
continue;
if (rhs->variable() &&
(!rhs->variable()->typeStartToken() || !rhs->variable()->typeStartToken()->isStandardType()))
continue;
}
// bailout if operation is protected by ?:
bool ternary = false;
for (const Token *parent = tok; parent; parent = parent->astParent()) {
if (Token::Match(parent, "?|:")) {
ternary = true;
break;
}
}
if (ternary)
if (rhs->variable() &&
(!rhs->variable()->typeStartToken() || !rhs->variable()->typeStartToken()->isStandardType()))
continue;
// Get negative rhs value. preferably a value which doesn't have 'condition'.
const ValueFlow::Value *value = tok->astOperand2()->getValueLE(-1LL, _settings);
if (value)
negativeBitwiseShiftError(tok);
}
// bailout if operation is protected by ?:
bool ternary = false;
for (const Token *parent = tok; parent; parent = parent->astParent()) {
if (Token::Match(parent, "?|:")) {
ternary = true;
break;
}
}
if (ternary)
continue;
// Get negative rhs value. preferably a value which doesn't have 'condition'.
if (tok->astOperand1()->getValueLE(-1LL, _settings))
negativeBitwiseShiftError(tok, 1);
else if (tok->astOperand2()->getValueLE(-1LL, _settings))
negativeBitwiseShiftError(tok, 2);
}
}
void CheckOther::negativeBitwiseShiftError(const Token *tok)
void CheckOther::negativeBitwiseShiftError(const Token *tok, int op)
{
reportError(tok, Severity::error, "shiftNegative", "Shifting by a negative value is undefined behaviour");
if (op == 1) // LHS
reportError(tok, Severity::error, "shiftNegative", "Shifting a negative value is undefined behaviour");
else // RHS
reportError(tok, Severity::error, "shiftNegative", "Shifting by a negative value is undefined behaviour");
}
//---------------------------------------------------------------------------

4
lib/checkother.h
View File

@ -243,7 +243,7 @@ private:
void unsignedPositiveError(const Token *tok, const std::string &varname, bool inconclusive);
void pointerPositiveError(const Token *tok, bool inconclusive);
void SuspiciousSemicolonError(const Token *tok);
void negativeBitwiseShiftError(const Token *tok);
void negativeBitwiseShiftError(const Token *tok, int op);
void redundantCopyError(const Token *tok, const std::string &varname);
void incompleteArrayFillError(const Token* tok, const std::string& buffer, const std::string& function, bool boolean);
void varFuncNullUBError(const Token *tok);
@ -260,7 +260,7 @@ private:
c.zerodivcondError(0,0,false);
c.misusedScopeObjectError(NULL, "varname");
c.invalidPointerCastError(0, "float", "double", false);
c.negativeBitwiseShiftError(0);
c.negativeBitwiseShiftError(0,1);
c.checkPipeParameterSizeError(0, "varname", "dimension");
c.raceAfterInterlockedDecrementError(0);

4
test/testother.cpp
View File

@ -4774,6 +4774,10 @@ private:
check("x = y ? z << $-1 : 0;\n");
ASSERT_EQUALS("", errout.str());
// Negative LHS
check("const int x = -1 >> 2;");
ASSERT_EQUALS("[test.cpp:1]: (error) Shifting a negative value is undefined behaviour\n", errout.str());
}
void incompleteArrayFill() {