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Fix issue 8501: false negative: (style) Opposite expression on both sides of (#3012)

This commit is contained in:
Paul Fultz II 2021-01-05 05:07:27 -06:00 committed by GitHub
parent b3b7ecc7ea
commit a95c931da0
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3 changed files with 48 additions and 46 deletions
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62
lib/astutils.cpp
View File

@ -648,6 +648,18 @@ bool exprDependsOnThis(const Token* expr, nonneg int depth)
return exprDependsOnThis(expr->astOperand1(), depth) || exprDependsOnThis(expr->astOperand2(), depth);
}
static bool hasUnknownVars(const Token* startTok) {
bool result = false;
visitAstNodes(startTok, [&](const Token* tok) {
if (tok->varId() > 0 && !tok->variable()) {
result = true;
return ChildrenToVisit::done;
}
return ChildrenToVisit::op1_and_op2;
});
return result;
}
/// This takes a token that refers to a variable and it will return the token
/// to the expression that the variable is assigned to. If its not valid to
/// make such substitution then it will return the original token.
@ -671,11 +683,7 @@ static const Token * followVariableExpression(const Token * tok, bool cpp, const
const Token * varTok = getVariableInitExpression(var);
if (!varTok)
return tok;
// Bailout. If variable value depends on value of "this".
if (exprDependsOnThis(varTok))
return tok;
// Skip array access
if (Token::simpleMatch(varTok, "["))
if (hasUnknownVars(varTok))
return tok;
if (var->isVolatile())
return tok;
@ -692,44 +700,14 @@ static const Token * followVariableExpression(const Token * tok, bool cpp, const
return tok;
if (precedes(varTok, endToken) && isAliased(varTok, endToken, tok->varId()))
return tok;
if (varTok->exprId() != 0 && isVariableChanged(nextAfterAstRightmostLeaf(varTok), endToken, varTok->exprId(), false, nullptr, cpp))
const Token* startToken = nextAfterAstRightmostLeaf(varTok);
if (!startToken)
startToken = varTok;
if (varTok->exprId() == 0) {
if (!varTok->isLiteral())
return tok;
} else if (isExpressionChanged(varTok, startToken, endToken, nullptr, cpp)) {
return tok;
// Start at beginning of initialization
const Token * startToken = varTok;
while (Token::Match(startToken, "%op%|.|(|{") && startToken->astOperand1())
startToken = startToken->astOperand1();
// Skip if the variable its referring to is modified
for (const Token * tok2 = startToken; tok2 != endToken; tok2 = tok2->next()) {
if (Token::simpleMatch(tok2, ";"))
break;
if (tok2->astParent() && tok2->isUnaryOp("*"))
return tok;
if (tok2->tokType() == Token::eIncDecOp ||
tok2->isAssignmentOp() ||
Token::Match(tok2, "%name% .|[|++|--|%assign%")) {
return tok;
}
if (Token::Match(tok2, "%name% ("))
// Bailout when function call is seen
return tok;
if (const Variable * var2 = tok2->variable()) {
if (!var2->scope())
return tok;
const Token * endToken2 = var2->scope() != tok->scope() ? var2->scope()->bodyEnd : endToken;
if (!var2->isLocal() && !var2->isConst() && !var2->isArgument())
return tok;
if (var2->isStatic() && !var2->isConst())
return tok;
if (!var2->isConst() && (!precedes(tok2, endToken2) || isVariableChanged(tok2, endToken2, tok2->varId(), false, nullptr, cpp)))
return tok;
if (precedes(tok2, endToken2) && isAliased(tok2, endToken2, tok2->varId()))
return tok;
// Recognized as a variable but the declaration is unknown
} else if (tok2->varId() > 0) {
return tok;
} else if (tok2->tokType() == Token::eName && !Token::Match(tok2, "sizeof|decltype|typeof") && !tok2->function()) {
return tok;
}
}
return varTok;
}

2
lib/symboldatabase.cpp
View File

@ -1433,7 +1433,7 @@ void SymbolDatabase::createSymbolDatabaseExprIds()
for (Token* tok = const_cast<Token*>(scope->bodyStart); tok != scope->bodyEnd; tok = tok->next()) {
if (tok->varId() > 0) {
tok->exprId(tok->varId());
} else if (Token::Match(tok, "(|.|%cop%")) {
} else if (Token::Match(tok, "(|.|[|%cop%")) {
exprs[tok->str()].push_back(tok);
tok->exprId(id++);
}

30
test/testother.cpp
View File

@ -4953,13 +4953,13 @@ private:
" const int i = sizeof(int);\n"
" if ( i != sizeof (int)){}\n"
"}\n");
TODO_ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:3]: (style) The comparison 'i != sizeof(int)' is always false because 'i' and 'sizeof(int)' represent the same value.\n", "", errout.str());
ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:3]: (style) The comparison 'i != sizeof(int)' is always false because 'i' and 'sizeof(int)' represent the same value.\n", errout.str());
check("void f() {\n"
" const int i = sizeof(int);\n"
" if ( sizeof (int) != i){}\n"
"}\n");
TODO_ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:3]: (style) The comparison 'sizeof(int) != i' is always false because 'sizeof(int)' and 'i' represent the same value.\n", "", errout.str());
ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:3]: (style) The comparison 'sizeof(int) != i' is always false because 'sizeof(int)' and 'i' represent the same value.\n", errout.str());
check("void f(int a = 1) { if ( a != 1){}}\n");
ASSERT_EQUALS("", errout.str());
@ -5100,7 +5100,7 @@ private:
check("struct A { int f() const; };\n"
"A g();\n"
"void foo() {\n"
" for (const A x = A();;) {\n"
" for (A x = A();;) {\n"
" const int a = x.f();\n"
" x = g();\n"
" if (x.f() == a) break;\n"
@ -5506,6 +5506,30 @@ private:
" if (!b && g()) {}\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("void f(bool *a) {\n"
" const bool b = a[42];\n"
" if( b == !(a[42]) ) {}\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:3]: (style) Opposite expression on both sides of '=='.\n", errout.str());
check("void f(bool *a) {\n"
" const bool b = a[42];\n"
" if( a[42] == !(b) ) {}\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:3]: (style) Opposite expression on both sides of '=='.\n", errout.str());
check("void f(bool *a) {\n"
" const bool b = *a;\n"
" if( b == !(*a) ) {}\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:3]: (style) Opposite expression on both sides of '=='.\n", errout.str());
check("void f(bool *a) {\n"
" const bool b = *a;\n"
" if( *a == !(b) ) {}\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:3]: (style) Opposite expression on both sides of '=='.\n", errout.str());
}
void duplicateVarExpression() {