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

Fixed #5845 (new check: same condition after noreturn conditional code => second condition is always false)

This commit is contained in:
Daniel Marjamäki 2017-09-03 10:34:34 +02:00
parent 8aa568f085
commit f2ec5f24ce
3 changed files with 54 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

37
lib/checkcondition.cpp
View File

@ -441,10 +441,12 @@ void CheckCondition::multiConditionError(const Token *tok, unsigned int line1)
}
//---------------------------------------------------------------------------
// Detect oppositing inner and outer conditions
// - Opposite inner conditions => always false
// - (TODO) Same/Overlapping inner condition => always true
// - same condition after early exit => always false
//---------------------------------------------------------------------------
void CheckCondition::oppositeInnerCondition()
void CheckCondition::multiCondition2()
{
if (!_settings->isEnabled(Settings::WARNING))
return;
@ -496,9 +498,19 @@ void CheckCondition::oppositeInnerCondition()
}
}
// parse until inner condition is reached..
// parse until second condition is reached..
enum MULTICONDITIONTYPE { INNER, AFTER } type;
const Token *tok;
if (Token::Match(scope->classStart, "{ return|throw|continue|break")) {
tok = scope->classEnd->next();
type = MULTICONDITIONTYPE::AFTER;
} else {
tok = scope->classStart;
type = MULTICONDITIONTYPE::INNER;
}
const Token * const endToken = tok->scope()->classEnd;
const Token *ifToken = nullptr;
for (const Token *tok = scope->classStart; tok && tok != scope->classEnd; tok = tok->next()) {
for (; tok && tok != endToken; tok = tok->next()) {
if (Token::simpleMatch(tok, "if (")) {
ifToken = tok;
break;
@ -539,8 +551,13 @@ void CheckCondition::oppositeInnerCondition()
// Condition..
const Token *cond2 = ifToken->next()->astOperand2();
if (isOppositeCond(false, _tokenizer->isCPP(), cond1, cond2, _settings->library, true))
oppositeInnerConditionError(cond1, cond2);
if (type == MULTICONDITIONTYPE::INNER) {
if (isOppositeCond(false, _tokenizer->isCPP(), cond1, cond2, _settings->library, true))
oppositeInnerConditionError(cond1, cond2);
} else {
if (isSameExpression(_tokenizer->isCPP(), true, cond1, cond2, _settings->library, true))
sameConditionAfterEarlyExitError(cond1, cond2);
}
}
}
@ -552,6 +569,14 @@ void CheckCondition::oppositeInnerConditionError(const Token *tok1, const Token*
reportError(errorPath, Severity::warning, "oppositeInnerCondition", "Opposite inner 'if' condition leads to a dead code block.", CWE398, false);
}
void CheckCondition::sameConditionAfterEarlyExitError(const Token *cond1, const Token* cond2)
{
ErrorPath errorPath;
errorPath.push_back(ErrorPathItem(cond1, "first condition"));
errorPath.push_back(ErrorPathItem(cond2, "second condition"));
reportError(errorPath, Severity::warning, "sameConditionAfterEarlyExit", "Same condition, second condition is always false", CWE398, false);
}
//---------------------------------------------------------------------------
// if ((x != 1) || (x != 3)) // expression always true
// if ((x == 1) && (x == 3)) // expression always false

17
lib/checkcondition.h
View File

@ -55,7 +55,7 @@ public:
CheckCondition checkCondition(tokenizer, settings, errorLogger);
checkCondition.multiCondition();
checkCondition.clarifyCondition(); // not simplified because ifAssign
checkCondition.oppositeInnerCondition();
checkCondition.multiCondition2();
checkCondition.checkIncorrectLogicOperator();
checkCondition.checkInvalidTestForOverflow();
checkCondition.alwaysTrueFalse();
@ -90,8 +90,13 @@ public:
/** match 'if' and 'else if' conditions */
void multiCondition();
/** To check the dead code in a program, which is inaccessible due to the counter-conditions check in nested-if statements **/
void oppositeInnerCondition();
/**
* multiconditions #2
* - Opposite inner conditions => always false
* - (TODO) Same/Overlapping inner condition => always true
* - same condition after early exit => always false
**/
void multiCondition2();
/** @brief %Check for testing for mutual exclusion over ||*/
void checkIncorrectLogicOperator();
@ -124,6 +129,8 @@ private:
void oppositeInnerConditionError(const Token *tok1, const Token* tok2);
void sameConditionAfterEarlyExitError(const Token *cond1, const Token *cond2);
void incorrectLogicOperatorError(const Token *tok, const std::string &condition, bool always, bool inconclusive);
void redundantConditionError(const Token *tok, const std::string &text, bool inconclusive);
@ -144,6 +151,7 @@ private:
c.multiConditionError(nullptr,1);
c.mismatchingBitAndError(nullptr, 0xf0, nullptr, 1);
c.oppositeInnerConditionError(nullptr, nullptr);
c.sameConditionAfterEarlyExitError(nullptr, nullptr);
c.incorrectLogicOperatorError(nullptr, "foo > 3 && foo < 4", true, false);
c.redundantConditionError(nullptr, "If x > 11 the condition x > 10 is always true.", false);
c.moduloAlwaysTrueFalseError(nullptr, "1");
@ -163,7 +171,8 @@ private:
"- Detect usage of | where & should be used\n"
"- Detect matching 'if' and 'else if' conditions\n"
"- Mismatching bitand (a &= 0xf0; a &= 1; => a = 0)\n"
"- Find dead code which is inaccessible due to the counter-conditions check in nested if statements\n"
"- Opposite inner condition is always false\n"
"- Same condition after early exit is always false\n"
"- Condition that is always true/false\n"
"- Mutual exclusion over || always evaluating to true\n"
"- Comparisons of modulo results that are always true/false.\n"

10
test/testcondition.cpp
View File

@ -79,6 +79,8 @@ private:
TEST_CASE(oppositeInnerCondition2);
TEST_CASE(oppositeInnerConditionAnd);
TEST_CASE(sameConditionAfterEarlyExit);
TEST_CASE(clarifyCondition1); // if (a = b() < 0)
TEST_CASE(clarifyCondition2); // if (a & b == c)
TEST_CASE(clarifyCondition3); // if (! a & b)
@ -1709,6 +1711,14 @@ private:
ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:3]: (warning) Opposite inner 'if' condition leads to a dead code block.\n", errout.str());
}
void sameConditionAfterEarlyExit() {
check("void f(int x) {\n"
" if (x > 100) { return; }\n"
" if (x > 100) {}\n"
"}");
ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:3]: (warning) Same condition, second condition is always false\n", errout.str());
}
// clarify conditions with = and comparison
void clarifyCondition1() {
check("void f() {\n"