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Track lifetimes of lambdas that capture the 'this' variable (#3594)

This commit is contained in:
Paul Fultz II 2021-12-04 10:00:55 -06:00 committed by GitHub
parent 9ddc7f2d71
commit a03e731930
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GPG Key ID: 4AEE18F83AFDEB23
5 changed files with 142 additions and 23 deletions
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15
lib/symboldatabase.cpp
View File

@ -5277,6 +5277,11 @@ const Function* SymbolDatabase::findFunction(const Token *tok) const
const Token* tok1 = tok->previous()->astOperand1();
if (tok1 && tok1->valueType() && tok1->valueType()->typeScope) {
return tok1->valueType()->typeScope->findFunction(tok, tok1->valueType()->constness == 1);
} else if (tok1 && Token::Match(tok1->previous(), "%name% (") && tok1->previous()->function() &&
tok1->previous()->function()->retDef) {
ValueType vt = ValueType::parseDecl(tok1->previous()->function()->retDef, mSettings);
if (vt.typeScope)
return vt.typeScope->findFunction(tok, vt.constness == 1);
} else if (Token::Match(tok1, "%var% .")) {
const Variable *var = getVariableFromVarId(tok1->varId());
if (var && var->typeScope())
@ -6554,6 +6559,16 @@ void SymbolDatabase::setValueTypeInTokenList(bool reportDebugWarnings, Token *to
// library type/function
else if (tok->previous()) {
// Aggregate constructor
if (Token::Match(tok->previous(), "%name%")) {
ValueType valuetype;
if (parsedecl(tok->previous(), &valuetype, mDefaultSignedness, mSettings)) {
if (valuetype.typeScope) {
setValueType(tok, valuetype);
continue;
}
}
}
if (tok->astParent() && Token::Match(tok->astOperand1(), "%name%|::")) {
const Token *typeStartToken = tok->astOperand1();
while (typeStartToken && typeStartToken->str() == "::")

100
lib/valueflow.cpp
View File

@ -3619,18 +3619,27 @@ struct LifetimeStore {
if (argtok->values().empty()) {
ErrorPath er;
er.emplace_back(argtok, message);
const Variable *var = getLifetimeVariable(argtok, er);
if (var && var->isArgument()) {
for (const LifetimeToken& lt : getLifetimeTokens(argtok)) {
if (!settings->certainty.isEnabled(Certainty::inconclusive) && lt.inconclusive)
continue;
ValueFlow::Value value;
value.valueType = ValueFlow::Value::ValueType::LIFETIME;
value.lifetimeScope = ValueFlow::Value::LifetimeScope::Argument;
value.tokvalue = var->nameToken();
value.tokvalue = lt.token;
value.errorPath = er;
value.lifetimeKind = type;
value.setInconclusive(inconclusive);
value.setInconclusive(inconclusive || lt.inconclusive);
const Variable* var = lt.token->variable();
if (var && var->isArgument()) {
value.lifetimeScope = ValueFlow::Value::LifetimeScope::Argument;
} else if (exprDependsOnThis(lt.token)) {
value.lifetimeScope = ValueFlow::Value::LifetimeScope::ThisPointer;
} else {
continue;
}
// Don't add the value a second time
if (std::find(tok->values().begin(), tok->values().end(), value) != tok->values().end())
return false;
continue;
;
setTokenValue(tok, value, tokenlist->getSettings());
update = true;
}
@ -3798,7 +3807,10 @@ static void valueFlowLifetimeFunction(Token *tok, TokenList *tokenlist, ErrorLog
continue;
if (!v.tokvalue)
continue;
if (exprDependsOnThis(v.tokvalue) && memtok) {
if (memtok &&
(contains({ValueFlow::Value::LifetimeScope::ThisPointer, ValueFlow::Value::LifetimeScope::ThisValue},
v.lifetimeScope) ||
exprDependsOnThis(v.tokvalue))) {
LifetimeStore ls = LifetimeStore{memtok,
"Passed to member function '" + tok->expressionString() + "'.",
ValueFlow::Value::LifetimeKind::Object};
@ -3806,7 +3818,10 @@ static void valueFlowLifetimeFunction(Token *tok, TokenList *tokenlist, ErrorLog
ls.forward = false;
ls.errorPath = v.errorPath;
ls.errorPath.emplace_front(returnTok, "Return " + lifetimeType(returnTok, &v) + ".");
update |= ls.byRef(tok->next(), tokenlist, errorLogger, settings);
if (v.lifetimeScope == ValueFlow::Value::LifetimeScope::ThisValue)
update |= ls.byVal(tok->next(), tokenlist, errorLogger, settings);
else
update |= ls.byRef(tok->next(), tokenlist, errorLogger, settings);
continue;
}
const Variable *var = v.tokvalue->variable();
@ -3953,7 +3968,11 @@ struct Lambda {
bodyTok = afterArguments;
}
for (const Token* c:getCaptures()) {
if (c->variable()) {
if (Token::Match(c, "this !!.")) {
explicitCaptures[c->variable()] = std::make_pair(c, Capture::ByReference);
} else if (Token::simpleMatch(c, "* this")) {
explicitCaptures[c->next()->variable()] = std::make_pair(c->next(), Capture::ByValue);
} else if (c->variable()) {
explicitCaptures[c->variable()] = std::make_pair(c, Capture::ByValue);
} else if (c->isUnaryOp("&") && Token::Match(c->astOperand1(), "%var%")) {
explicitCaptures[c->astOperand1()->variable()] = std::make_pair(c->astOperand1(), Capture::ByReference);
@ -4023,6 +4042,7 @@ static void valueFlowLifetime(TokenList *tokenlist, SymbolDatabase*, ErrorLogger
std::set<const Scope *> scopes;
// Avoid capturing a variable twice
std::set<nonneg int> varids;
bool capturedThis = false;
auto isImplicitCapturingVariable = [&](const Token *varTok) {
const Variable *var = varTok->variable();
@ -4063,23 +4083,65 @@ static void valueFlowLifetime(TokenList *tokenlist, SymbolDatabase*, ErrorLogger
}
};
auto captureThisVariable = [&](const Token* tok2, Lambda::Capture c) {
ValueFlow::Value value;
value.valueType = ValueFlow::Value::ValueType::LIFETIME;
if (c == Lambda::Capture::ByReference)
value.lifetimeScope = ValueFlow::Value::LifetimeScope::ThisPointer;
else if (c == Lambda::Capture::ByValue)
value.lifetimeScope = ValueFlow::Value::LifetimeScope::ThisValue;
value.tokvalue = tok2;
value.errorPath.push_back({tok2, "Lambda captures the 'this' variable here."});
value.lifetimeKind = ValueFlow::Value::LifetimeKind::Lambda;
capturedThis = true;
// Don't add the value a second time
if (std::find(tok->values().begin(), tok->values().end(), value) != tok->values().end())
return;
setTokenValue(tok, value, tokenlist->getSettings());
update |= true;
};
// Handle explicit capture
for (const auto& p:lam.explicitCaptures) {
const Variable* var = p.first;
if (!var)
continue;
const Token* tok2 = p.second.first;
Lambda::Capture c = p.second.second;
captureVariable(tok2, c, [](const Token*) {
return true;
});
varids.insert(var->declarationId());
if (Token::Match(tok2, "this !!.")) {
captureThisVariable(tok2, c);
} else if (var) {
captureVariable(tok2, c, [](const Token*) {
return true;
});
varids.insert(var->declarationId());
}
}
auto isImplicitCapturingThis = [&](const Token* tok2) {
if (capturedThis)
return false;
if (Token::simpleMatch(tok2, "this")) {
return true;
} else if (tok2->variable()) {
if (Token::simpleMatch(tok2->previous(), "."))
return false;
const Variable* var = tok2->variable();
if (var->isLocal())
return false;
if (var->isArgument())
return false;
return exprDependsOnThis(tok2);
} else if (Token::simpleMatch(tok2, "(")) {
return exprDependsOnThis(tok2);
}
return false;
};
for (const Token * tok2 = lam.bodyTok; tok2 != lam.bodyTok->link(); tok2 = tok2->next()) {
if (!tok2->variable())
continue;
captureVariable(tok2, lam.implicitCapture, isImplicitCapturingVariable);
if (isImplicitCapturingThis(tok2)) {
captureThisVariable(tok2, Lambda::Capture::ByReference);
} else if (tok2->variable()) {
captureVariable(tok2, lam.implicitCapture, isImplicitCapturingVariable);
}
}
if (update)
valueFlowForwardLifetime(tok, tokenlist, errorLogger, settings);
@ -4188,7 +4250,7 @@ static void valueFlowLifetime(TokenList *tokenlist, SymbolDatabase*, ErrorLogger
valueFlowLifetimeConstructor(tok->next(), tokenlist, errorLogger, settings);
}
// Check function calls
else if (Token::Match(tok, "%name% (")) {
else if (Token::Match(tok, "%name% (") && !Token::simpleMatch(tok->next()->link(), ") {")) {
valueFlowLifetimeFunction(tok, tokenlist, errorLogger, settings);
}
// Unique pointer lifetimes

2
lib/valueflow.h
View File

@ -376,7 +376,7 @@ namespace ValueFlow {
Address
} lifetimeKind;
enum class LifetimeScope { Local, Argument, SubFunction } lifetimeScope;
enum class LifetimeScope { Local, Argument, SubFunction, ThisPointer, ThisValue } lifetimeScope;
static const char* toString(MoveKind moveKind);
static const char* toString(LifetimeKind lifetimeKind);

40
test/testautovariables.cpp
View File

@ -2954,7 +2954,7 @@ private:
" return by_value(v.begin());\n"
"}\n");
ASSERT_EQUALS(
"[test.cpp:7] -> [test.cpp:7] -> [test.cpp:3] -> [test.cpp:3] -> [test.cpp:2] -> [test.cpp:6] -> [test.cpp:7]: (error) Returning object that points to local variable 'v' that will be invalid when returning.\n",
"[test.cpp:7] -> [test.cpp:7] -> [test.cpp:3] -> [test.cpp:3] -> [test.cpp:6] -> [test.cpp:7]: (error) Returning object that points to local variable 'v' that will be invalid when returning.\n",
errout.str());
check("auto by_ref(int& x) {\n"
@ -3350,6 +3350,44 @@ private:
ASSERT_EQUALS(
"[test.cpp:9] -> [test.cpp:9] -> [test.cpp:14] -> [test.cpp:13] -> [test.cpp:14]: (error) Returning pointer to local variable 'fred' that will be invalid when returning.\n",
errout.str());
check("struct A {\n"
" int i;\n"
" auto f() const {\n"
" return [=]{ return i; };\n"
" }\n"
"};\n"
"auto g() {\n"
" return A().f();\n"
"}\n");
ASSERT_EQUALS(
"[test.cpp:4] -> [test.cpp:4] -> [test.cpp:8] -> [test.cpp:8]: (error) Returning object that will be invalid when returning.\n",
errout.str());
check("struct A {\n"
" int i;\n"
" auto f() const {\n"
" return [*this]{ return i; };\n"
" }\n"
"};\n"
"auto g() {\n"
" return A().f();\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("struct A {\n"
" int* i;\n"
" auto f() const {\n"
" return [*this]{ return i; };\n"
" }\n"
"};\n"
"auto g() {\n"
" int i = 0;\n"
" return A{&i}.f();\n"
"}\n");
ASSERT_EQUALS(
"[test.cpp:9] -> [test.cpp:9] -> [test.cpp:9] -> [test.cpp:4] -> [test.cpp:4] -> [test.cpp:8] -> [test.cpp:9]: (error) Returning object that points to local variable 'i' that will be invalid when returning.\n",
errout.str());
}
void invalidLifetime() {

8
test/teststl.cpp
View File

@ -1588,7 +1588,9 @@ private:
"void foo() {\n"
" (void)std::find(A().f().begin(), A().g().end(), 0);\n"
"}");
ASSERT_EQUALS("[test.cpp:6]: (warning) Iterators to containers from different expressions 'A().f()' and 'A().g()' are used together.\n", errout.str());
ASSERT_EQUALS(
"[test.cpp:6]: (error) Iterators of different containers 'A().f()' and 'A().g()' are used together.\n",
errout.str());
check("struct A {\n"
" std::vector<int>& f();\n"
@ -1597,7 +1599,9 @@ private:
"void foo() {\n"
" (void)std::find(A{} .f().begin(), A{} .g().end(), 0);\n"
"}");
ASSERT_EQUALS("[test.cpp:6]: (warning) Iterators to containers from different expressions 'A{}.f()' and 'A{}.g()' are used together.\n", errout.str());
ASSERT_EQUALS(
"[test.cpp:6]: (error) Iterators of different containers 'A{}.f()' and 'A{}.g()' are used together.\n",
errout.str());
check("std::vector<int>& f();\n"
"std::vector<int>& g();\n"