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Same expression when comparing with zero (#2762)

This commit is contained in:
Paul Fultz II 2020-08-31 01:48:48 -05:00 committed by GitHub
parent 1c5f496350
commit 3e99bff764
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3 changed files with 97 additions and 1 deletions
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44
lib/astutils.cpp
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@ -729,6 +729,11 @@ static bool isSameConstantValue(bool macro, const Token * const tok1, const Toke
return isEqualKnownValue(tok1, tok2);
}
static bool astIsBoolLike(const Token* tok)
{
return astIsBool(tok) || astIsPointer(tok) || astIsSmartPointer(tok);
}
bool isSameExpression(bool cpp, bool macro, const Token *tok1, const Token *tok2, const Library& library, bool pure, bool followVar, ErrorPath* errors)
{
if (tok1 == nullptr && tok2 == nullptr)
@ -777,6 +782,45 @@ bool isSameExpression(bool cpp, bool macro, const Token *tok1, const Token *tok2
return isSameExpression(cpp, macro, tok1->astOperand1(), tok2->astOperand2(), library, pure, followVar, errors) &&
isSameExpression(cpp, macro, tok1->astOperand2(), tok2->astOperand1(), library, pure, followVar, errors);
}
const Token* condTok = nullptr;
const Token* exprTok = nullptr;
if (Token::Match(tok1, "==|!=")) {
condTok = tok1;
exprTok = tok2;
} else if (Token::Match(tok2, "==|!=")) {
condTok = tok2;
exprTok = tok1;
}
if (condTok && condTok->astOperand1() && condTok->astOperand2() && !Token::Match(exprTok, "%comp%")) {
const Token* varTok1 = nullptr;
const Token* varTok2 = exprTok;
const ValueFlow::Value* value = nullptr;
if (condTok->astOperand1()->hasKnownIntValue()) {
value = &condTok->astOperand1()->values().front();
varTok1 = condTok->astOperand2();
} else if (condTok->astOperand2()->hasKnownIntValue()) {
value = &condTok->astOperand2()->values().front();
varTok1 = condTok->astOperand1();
}
if (Token::simpleMatch(exprTok, "!"))
varTok2 = exprTok->astOperand1();
bool compare = false;
if (value) {
if (value->intvalue == 0 && Token::simpleMatch(exprTok, "!") && Token::simpleMatch(condTok, "==")) {
compare = true;
} else if (value->intvalue == 0 && !Token::simpleMatch(exprTok, "!") && Token::simpleMatch(condTok, "!=")) {
compare = true;
} else if (value->intvalue != 0 && Token::simpleMatch(exprTok, "!") && Token::simpleMatch(condTok, "!=")) {
compare = true;
} else if (value->intvalue != 0 && !Token::simpleMatch(exprTok, "!") && Token::simpleMatch(condTok, "==")) {
compare = true;
}
}
if (compare && astIsBoolLike(varTok1) && astIsBoolLike(varTok2))
return isSameExpression(cpp, macro, varTok1, varTok2, library, pure, followVar, errors);
}
return false;
}
if (macro && (tok1->isExpandedMacro() || tok2->isExpandedMacro() || tok1->isTemplateArg() || tok2->isTemplateArg()))

2
test/testcondition.cpp
View File

@ -3205,7 +3205,7 @@ private:
" if (handle) return 1;\n"
" else return 0;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:3]: (style) Condition 'handle' is always false\n", errout.str());
ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:3]: (warning) Identical condition 'handle!=0', second condition is always false\n", errout.str());
check("void f(void* x, void* y) {\n"
" if (x == nullptr && y == nullptr)\n"

52
test/testother.cpp
View File

@ -149,6 +149,7 @@ private:
TEST_CASE(duplicateValueTernary);
TEST_CASE(duplicateExpressionTernary); // #6391
TEST_CASE(duplicateExpressionTemplate); // #6930
TEST_CASE(duplicateExpressionCompareWithZero);
TEST_CASE(oppositeExpression);
TEST_CASE(duplicateVarExpression);
TEST_CASE(duplicateVarExpressionUnique);
@ -5073,6 +5074,57 @@ private:
ASSERT_EQUALS("", errout.str());
}
void duplicateExpressionCompareWithZero() {
check("void f(int* x, bool b) {\n"
" if ((x && b) || (x != 0 && b)) {}\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2]: (style) Same expression on both sides of '||' because 'x&&b' and 'x!=0&&b' represent the same value.\n", errout.str());
check("void f(int* x, bool b) {\n"
" if ((x != 0 && b) || (x && b)) {}\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2]: (style) Same expression on both sides of '||' because 'x!=0&&b' and 'x&&b' represent the same value.\n", errout.str());
check("void f(int* x, bool b) {\n"
" if ((x && b) || (b && x != 0)) {}\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2]: (style) Same expression on both sides of '||' because 'x&&b' and 'b&&x!=0' represent the same value.\n", errout.str());
check("void f(int* x, bool b) {\n"
" if ((!x && b) || (x == 0 && b)) {}\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2]: (style) Same expression on both sides of '||' because '!x&&b' and 'x==0&&b' represent the same value.\n", errout.str());
check("void f(int* x, bool b) {\n"
" if ((x == 0 && b) || (!x && b)) {}\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2]: (style) Same expression on both sides of '||' because 'x==0&&b' and '!x&&b' represent the same value.\n", errout.str());
check("void f(int* x, bool b) {\n"
" if ((!x && b) || (b && x == 0)) {}\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2]: (style) Same expression on both sides of '||' because '!x&&b' and 'b&&x==0' represent the same value.\n", errout.str());
check("struct A {\n"
" int* getX() const;\n"
" bool getB() const;\n"
" void f() {\n"
" if ((getX() && getB()) || (getX() != 0 && getB())) {}\n"
" }\n"
"};\n");
ASSERT_EQUALS("[test.cpp:5]: (style) Same expression on both sides of '||' because 'getX()&&getB()' and 'getX()!=0&&getB()' represent the same value.\n", errout.str());
check("void f(int* x, bool b) {\n"
" if ((x && b) || (x == 0 && b)) {}\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("void f(int* x, bool b) {\n"
" if ((!x && b) || (x != 0 && b)) {}\n"
"}\n");
ASSERT_EQUALS("", errout.str());
}
void oppositeExpression() {
check("void f(bool a) { if(a && !a) {} }");
ASSERT_EQUALS("[test.cpp:1]: (style) Opposite expression on both sides of '&&'.\n", errout.str());