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Partial fix 11154: FN: knownConditionTrueFalse (#4453) 

* Partial fix 11154: FN: knownConditionTrueFalse

* Formay

* Add more tests

* FOrmat

* Fix FP

* Add test

* Check for side effects

* Format

* Update tests

* Format
This commit is contained in:
Paul Fultz II 2022-09-08 15:08:38 -05:00 committed by GitHub
parent dbc05da356
commit 117a753b10
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GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 138 additions and 14 deletions
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18
lib/astutils.cpp
View File

@ -1616,6 +1616,9 @@ bool isOppositeCond(bool isNot, bool cpp, const Token * const cond1, const Token
if (!cond1 || !cond2)
return false;
if (isSameExpression(cpp, true, cond1, cond2, library, pure, followVar, errors))
return false;
if (!isNot && cond1->str() == "&&" && cond2->str() == "&&") {
for (const Token* tok1: {
cond1->astOperand1(), cond1->astOperand2()
@ -1631,6 +1634,21 @@ bool isOppositeCond(bool isNot, bool cpp, const Token * const cond1, const Token
}
}
if (cond1->str() != cond2->str() && (cond1->str() == "||" || cond2->str() == "||")) {
const Token* orCond = nullptr;
const Token* otherCond = nullptr;
if (cond1->str() == "||") {
orCond = cond1;
otherCond = cond2;
}
if (cond2->str() == "||") {
orCond = cond2;
otherCond = cond1;
}
return isOppositeCond(isNot, cpp, orCond->astOperand1(), otherCond, library, pure, followVar, errors) &&
isOppositeCond(isNot, cpp, orCond->astOperand2(), otherCond, library, pure, followVar, errors);
}
if (cond1->str() == "!") {
if (cond2->str() == "!=") {
if (cond2->astOperand1() && cond2->astOperand1()->str() == "0")

3
lib/checkcondition.cpp
View File

@ -1507,7 +1507,8 @@ void CheckCondition::alwaysTrueFalse()
continue;
if (Token::simpleMatch(tok, ":"))
continue;
if (tok->isComparisonOp() && isSameExpression(mTokenizer->isCPP(),
if (tok->isComparisonOp() && isWithoutSideEffects(mTokenizer->isCPP(), tok->astOperand1()) &&
isSameExpression(mTokenizer->isCPP(),
true,
tok->astOperand1(),
tok->astOperand2(),

20
lib/valueflow.cpp
View File

@ -3058,6 +3058,20 @@ struct ExpressionAnalyzer : SingleValueFlowAnalyzer {
}
};
struct SameExpressionAnalyzer : ExpressionAnalyzer {
SameExpressionAnalyzer() : ExpressionAnalyzer() {}
SameExpressionAnalyzer(const Token* e, const ValueFlow::Value& val, const TokenList* t)
: ExpressionAnalyzer(e, val, t)
{}
bool match(const Token* tok) const override
{
return isSameExpression(isCPP(), true, expr, tok, getSettings()->library, true, true);
}
};
struct OppositeExpressionAnalyzer : ExpressionAnalyzer {
bool isNot;
@ -4929,7 +4943,7 @@ static void valueFlowConditionExpressions(TokenList *tokenlist, SymbolDatabase*
{
for (const Token* condTok2 : getConditions(condTok, "&&")) {
if (is1) {
ExpressionAnalyzer a1(condTok2, makeConditionValue(1, condTok2, true), tokenlist);
SameExpressionAnalyzer a1(condTok2, makeConditionValue(1, condTok2, true), tokenlist);
valueFlowGenericForward(startTok, startTok->link(), a1, settings);
}
@ -4944,7 +4958,7 @@ static void valueFlowConditionExpressions(TokenList *tokenlist, SymbolDatabase*
if (Token::simpleMatch(startTok->link(), "} else {")) {
startTok = startTok->link()->tokAt(2);
for (const Token* condTok2:conds) {
ExpressionAnalyzer a1(condTok2, makeConditionValue(0, condTok2, false), tokenlist);
SameExpressionAnalyzer a1(condTok2, makeConditionValue(0, condTok2, false), tokenlist);
valueFlowGenericForward(startTok, startTok->link(), a1, settings);
if (is1) {
@ -4964,7 +4978,7 @@ static void valueFlowConditionExpressions(TokenList *tokenlist, SymbolDatabase*
continue;
}
for (const Token* condTok2:conds) {
ExpressionAnalyzer a1(condTok2, makeConditionValue(0, condTok2, false), tokenlist);
SameExpressionAnalyzer a1(condTok2, makeConditionValue(0, condTok2, false), tokenlist);
valueFlowGenericForward(startTok->link()->next(), scope2->bodyEnd, a1, settings);
if (is1) {

99
test/testcondition.cpp
View File

@ -105,6 +105,7 @@ private:
TEST_CASE(oppositeInnerCondition2);
TEST_CASE(oppositeInnerCondition3);
TEST_CASE(oppositeInnerConditionAnd);
TEST_CASE(oppositeInnerConditionOr);
TEST_CASE(oppositeInnerConditionEmpty);
TEST_CASE(oppositeInnerConditionFollowVar);
@ -1386,6 +1387,52 @@ private:
}
void incorrectLogicOperator12() { // #8696
check("struct A {\n"
" void f() const;\n"
"};\n"
"void foo(A a, A b) {\n"
" A x = b;\n"
" A y = b;\n"
" y.f();\n"
" if (a > x && a < y)\n"
" return;\n"
"}");
ASSERT_EQUALS(
"[test.cpp:5] -> [test.cpp:6] -> [test.cpp:8]: (warning) Logical conjunction always evaluates to false: a > x && a < y.\n",
errout.str());
check("struct A {\n"
" void f();\n"
"};\n"
"void foo(A a, A b) {\n"
" A x = b;\n"
" A y = b;\n"
" y.f();\n"
" if (a > x && a < y)\n"
" return;\n"
"}");
ASSERT_EQUALS("", errout.str());
check("void foo(A a, A b) {\n"
" A x = b;\n"
" A y = b;\n"
" y.f();\n"
" if (a > x && a < y)\n"
" return;\n"
"}");
ASSERT_EQUALS("", errout.str());
check("void foo(A a, A b) {\n"
" const A x = b;\n"
" const A y = b;\n"
" y.f();\n"
" if (a > x && a < y)\n"
" return;\n"
"}");
ASSERT_EQUALS(
"[test.cpp:2] -> [test.cpp:3] -> [test.cpp:5]: (warning) Logical conjunction always evaluates to false: a > x && a < y.\n",
errout.str());
check("struct A {\n"
" void f() const;\n"
"};\n"
@ -1396,7 +1443,9 @@ private:
" if (a > x && a < y)\n"
" return;\n"
"}");
ASSERT_EQUALS("[test.cpp:5] -> [test.cpp:6] -> [test.cpp:8]: (warning) Logical conjunction always evaluates to false: a > x && a < y.\n", errout.str());
ASSERT_EQUALS("[test.cpp:8]: (style) Condition 'a>x' is always false\n"
"[test.cpp:8]: (style) Condition 'a<y' is always false\n",
errout.str());
check("struct A {\n"
" void f();\n"
@ -1408,7 +1457,7 @@ private:
" if (a > x && a < y)\n"
" return;\n"
"}");
ASSERT_EQUALS("", errout.str());
ASSERT_EQUALS("[test.cpp:8]: (style) Condition 'a>x' is always false\n", errout.str());
check("void foo(A a) {\n"
" A x = a;\n"
@ -1417,7 +1466,7 @@ private:
" if (a > x && a < y)\n"
" return;\n"
"}");
ASSERT_EQUALS("", errout.str());
ASSERT_EQUALS("[test.cpp:5]: (style) Condition 'a>x' is always false\n", errout.str());
check("void foo(A a) {\n"
" const A x = a;\n"
@ -1426,7 +1475,9 @@ private:
" if (a > x && a < y)\n"
" return;\n"
"}");
ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:3] -> [test.cpp:5]: (warning) Logical conjunction always evaluates to false: a > x && a < y.\n", errout.str());
ASSERT_EQUALS("[test.cpp:5]: (style) Condition 'a>x' is always false\n"
"[test.cpp:5]: (style) Condition 'a<y' is always false\n",
errout.str());
}
void incorrectLogicOperator13() {
@ -2489,6 +2540,46 @@ private:
ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:3]: (warning) Opposite inner 'if' condition leads to a dead code block.\n", errout.str());
}
void oppositeInnerConditionOr()
{
check("void f(int x) {\n"
" if (x == 1 || x == 2) {\n"
" if (x == 3) {}\n"
" }\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:3]: (warning) Opposite inner 'if' condition leads to a dead code block.\n",
errout.str());
check("void f(int x) {\n"
" if (x == 1 || x == 2) {\n"
" if (x == 1) {}\n"
" }\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("void f(int x) {\n"
" if (x == 1 || x == 2) {\n"
" if (x == 2) {}\n"
" }\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("void f(std::string x) {\n"
" if (x == \"1\" || x == \"2\") {\n"
" if (x == \"1\") {}\n"
" }\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("void f(int x) {\n"
" if (x < 1 || x > 3) {\n"
" if (x == 3) {}\n"
" }\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:3]: (warning) Opposite inner 'if' condition leads to a dead code block.\n",
errout.str());
}
void oppositeInnerConditionEmpty() {
check("void f1(const std::string &s) { if(s.size() > 42) if(s.empty()) {}}");
ASSERT_EQUALS("[test.cpp:1] -> [test.cpp:1]: (warning) Opposite inner 'if' condition leads to a dead code block.\n", errout.str());