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Fix FP knowConditionTrueFalse (#4419) 

* Fix #10426 FN (style) Condition 's.empty()' is always false

* Fix test

* Fix FP knowConditionTrueFalse

* Check for casts

* Fix FP for user-defined functions

* Adjust condition detection

* Tweaks
This commit is contained in:
chrchr-github 2022-08-30 18:08:24 +02:00 committed by GitHub
parent 9d107d911b
commit 3925a27182
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3 changed files with 36 additions and 8 deletions
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15
lib/checkcondition.cpp
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@ -1512,15 +1512,20 @@ void CheckCondition::alwaysTrueFalse()
continue;
}
const Token* astTop = tok->astTop();
const bool constIfWhileExpression =
tok->astParent() && Token::Match(tok->astTop()->astOperand1(), "if|while") && !tok->astTop()->astOperand1()->isConstexpr() &&
tok->astParent() && Token::Match(astTop->astOperand1(), "if|while") && !astTop->astOperand1()->isConstexpr() &&
(Token::Match(tok->astParent(), "%oror%|&&") || Token::Match(tok->astParent()->astOperand1(), "if|while"));
const bool constValExpr = tok->isNumber() && Token::Match(tok->astParent(),"%oror%|&&|?"); // just one number in boolean expression
const bool compExpr = Token::Match(tok, "%comp%|!|("); // a compare expression
const bool compExpr = Token::Match(tok, "%comp%|!"); // a compare expression
const bool ternaryExpression = Token::simpleMatch(tok->astParent(), "?");
const bool returnExpression = Token::simpleMatch(tok->astTop(), "return") && (tok->isComparisonOp() || Token::Match(tok, "&&|%oror%"));
if (!(constIfWhileExpression || constValExpr || compExpr || ternaryExpression || returnExpression))
const bool isReturn = Token::simpleMatch(astTop, "return");
const bool returnExpression = isReturn && (tok->isComparisonOp() || Token::Match(tok, "&&|%oror%"));
const bool callExpression = Token::simpleMatch(tok, "(");
if (!(constIfWhileExpression || constValExpr || compExpr || ternaryExpression || returnExpression || callExpression))
continue;
// only warn for functions returning bool
if (isReturn && callExpression && !(scope->function && scope->function->retDef && scope->function->retDef->str() == "bool"))
continue;
const Token* expr1 = tok->astOperand1(), *expr2 = tok->astOperand2();

2
test/cfg/qt.cpp
View File

@ -29,7 +29,7 @@ void QString1(QString s)
}
}
int QString2()
bool QString2()
{
QString s;
// cppcheck-suppress knownConditionTrueFalse

27
test/testcondition.cpp
View File

@ -4307,15 +4307,38 @@ private:
ASSERT_EQUALS("", errout.str());
// #10426
check("void f() {\n"
check("int f() {\n"
" std::string s;\n"
" for (; !s.empty();) {}\n"
" for (; s.empty();) {}\n"
" if (s.empty()) {}\n"
" if ((bool)0) {}\n"
" return s.empty();"
"}\n");
ASSERT_EQUALS("[test.cpp:3]: (style) Condition '!s.empty()' is always false\n"
"[test.cpp:4]: (style) Condition 's.empty()' is always true\n"
"[test.cpp:5]: (style) Condition 's.empty()' is always true\n",
"[test.cpp:5]: (style) Condition 's.empty()' is always true\n"
"[test.cpp:6]: (style) Condition '(bool)0' is always false\n",
errout.str());
check("int f(bool b) {\n"
" if (b) return static_cast<int>(1);\n"
" return (int)0;\n"
"}\n"
"bool g(bool b) {\n"
" if (b) return static_cast<int>(1);\n"
" return (int)0;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:6]: (style) Condition 'static_cast<int>(1)' is always true\n"
"[test.cpp:7]: (style) Condition '(int)0' is always false\n",
errout.str());
check("int f() { return 3; }\n"
"int g() { return f(); }\n"
"int h() { if (f()) {} }\n"
"int i() { return f() == 3; }\n");
ASSERT_EQUALS("[test.cpp:3]: (style) Condition 'f()' is always true\n"
"[test.cpp:4]: (style) Condition 'f()==3' is always true\n",
errout.str());
}