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Merge pull request #2774 from pfultz2/lifetime-subfunction 

Extend lifetimes to subfunctions
This commit is contained in:
Daniel Marjamäki 2020-09-09 20:43:36 +02:00 committed by GitHub
parent 7c8c0ef3a2 34d65e25d6
commit 48a6852a4a
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GPG Key ID: 4AEE18F83AFDEB23
5 changed files with 107 additions and 21 deletions
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59
lib/checkautovariables.cpp
View File

@ -473,6 +473,25 @@ static bool isEscapedReference(const Variable* var)
return !isTemporary(true, vartok, nullptr, false);
}
static bool isDanglingSubFunction(const Token* tokvalue, const Token* tok)
{
if (!tokvalue)
return false;
const Variable* var = tokvalue->variable();
if (!var->isLocal())
return false;
Function* f = Scope::nestedInFunction(tok->scope());
if (!f)
return false;
const Token* parent = tokvalue->astParent();
while (parent && !Token::Match(parent->previous(), "%name% (")) {
parent = parent->astParent();
}
if (!Token::simpleMatch(parent, "("))
return false;
return exprDependsOnThis(parent);
}
void CheckAutoVariables::checkVarLifetimeScope(const Token * start, const Token * end)
{
if (!start)
@ -521,30 +540,34 @@ void CheckAutoVariables::checkVarLifetimeScope(const Token * start, const Token
}
for (const ValueFlow::Value& val:tok->values()) {
if (!val.isLocalLifetimeValue())
if (!val.isLocalLifetimeValue() && !val.isSubFunctionLifetimeValue())
continue;
const bool escape = Token::Match(tok->astParent(), "return|throw");
for (const LifetimeToken& lt : getLifetimeTokens(getParentLifetime(val.tokvalue), escape)) {
const Token * tokvalue = lt.token;
if (escape) {
if (getPointerDepth(tok) < getPointerDepth(tokvalue))
continue;
if (!isLifetimeBorrowed(tok, mSettings))
continue;
if ((tokvalue->variable() && !isEscapedReference(tokvalue->variable()) &&
isInScope(tokvalue->variable()->nameToken(), scope)) ||
isDeadTemporary(mTokenizer->isCPP(), tokvalue, tok, &mSettings->library)) {
errorReturnDanglingLifetime(tok, &val);
if (val.isLocalLifetimeValue()) {
if (escape) {
if (getPointerDepth(tok) < getPointerDepth(tokvalue))
continue;
if (!isLifetimeBorrowed(tok, mSettings))
continue;
if ((tokvalue->variable() && !isEscapedReference(tokvalue->variable()) &&
isInScope(tokvalue->variable()->nameToken(), scope)) ||
isDeadTemporary(mTokenizer->isCPP(), tokvalue, tok, &mSettings->library)) {
errorReturnDanglingLifetime(tok, &val);
break;
}
} else if (tokvalue->variable() && isDeadScope(tokvalue->variable()->nameToken(), tok->scope())) {
errorInvalidLifetime(tok, &val);
break;
} else if (!tokvalue->variable() &&
isDeadTemporary(mTokenizer->isCPP(), tokvalue, tok, &mSettings->library)) {
errorDanglingTemporaryLifetime(tok, &val);
break;
}
} else if (tokvalue->variable() && isDeadScope(tokvalue->variable()->nameToken(), tok->scope())) {
errorInvalidLifetime(tok, &val);
break;
} else if (!tokvalue->variable() &&
isDeadTemporary(mTokenizer->isCPP(), tokvalue, tok, &mSettings->library)) {
errorDanglingTemporaryLifetime(tok, &val);
break;
} else if (tokvalue->variable() && isInScope(tokvalue->variable()->nameToken(), tok->scope())) {
}
if (tokvalue->variable() && (isInScope(tokvalue->variable()->nameToken(), tok->scope()) ||
(val.isSubFunctionLifetimeValue() && isDanglingSubFunction(tokvalue, tok)))) {
const Variable * var = nullptr;
const Token * tok2 = tok;
if (Token::simpleMatch(tok->astParent(), "=")) {

12
lib/symboldatabase.h
View File

@ -1049,6 +1049,18 @@ public:
return false;
}
static Function* nestedInFunction(const Scope* scope)
{
while (scope) {
if (scope->type == Scope::eFunction)
break;
scope = scope->nestedIn;
}
if (!scope)
return nullptr;
return scope->function;
}
bool isClassOrStruct() const {
return (type == eClass || type == eStruct);
}

10
lib/valueflow.cpp
View File

@ -3928,6 +3928,10 @@ static void valueFlowLifetime(TokenList *tokenlist, SymbolDatabase*, ErrorLogger
valueFlowForwardLifetime(tok, tokenlist, errorLogger, settings);
}
}
// Forward any lifetimes
else if (std::any_of(tok->values().begin(), tok->values().end(), std::mem_fn(&ValueFlow::Value::isLifetimeValue))) {
valueFlowForwardLifetime(tok, tokenlist, errorLogger, settings);
}
}
}
@ -5491,8 +5495,6 @@ static void valueFlowSubFunction(TokenList* tokenlist, SymbolDatabase* symboldat
// passing value(s) to function
std::list<ValueFlow::Value> argvalues(getFunctionArgumentValues(argtok));
// Don't forward lifetime values
argvalues.remove_if(std::mem_fn(&ValueFlow::Value::isLifetimeValue));
// Don't forward container sizes for now since programmemory can't evaluate conditions
argvalues.remove_if(std::mem_fn(&ValueFlow::Value::isContainerSizeValue));
@ -5513,6 +5515,9 @@ static void valueFlowSubFunction(TokenList* tokenlist, SymbolDatabase* symboldat
"' value is " +
v.infoString());
v.path = 256 * v.path + id;
// Change scope of lifetime values
if (v.isLifetimeValue())
v.lifetimeScope = ValueFlow::Value::LifetimeScope::SubFunction;
}
// passed values are not "known"..
@ -6709,6 +6714,7 @@ void ValueFlow::setValues(TokenList *tokenlist, SymbolDatabase* symboldatabase,
valueFlowForLoop(tokenlist, symboldatabase, errorLogger, settings);
valueFlowSubFunction(tokenlist, symboldatabase, errorLogger, settings);
valueFlowFunctionReturn(tokenlist, errorLogger);
valueFlowLifetime(tokenlist, symboldatabase, errorLogger, settings);
valueFlowFunctionDefaultParameter(tokenlist, symboldatabase, errorLogger, settings);
valueFlowUninit(tokenlist, symboldatabase, errorLogger, settings);
if (tokenlist->isCPP()) {

7
lib/valueflow.h
View File

@ -217,6 +217,11 @@ namespace ValueFlow {
return valueType == ValueType::LIFETIME && lifetimeScope == LifetimeScope::Argument;
}
bool isSubFunctionLifetimeValue() const
{
return valueType == ValueType::LIFETIME && lifetimeScope == LifetimeScope::SubFunction;
}
bool isNonValue() const {
return isMovedValue() || isUninitValue() || isLifetimeValue();
}
@ -263,7 +268,7 @@ namespace ValueFlow {
enum class LifetimeKind {Object, SubObject, Lambda, Iterator, Address} lifetimeKind;
enum class LifetimeScope { Local, Argument } lifetimeScope;
enum class LifetimeScope { Local, Argument, SubFunction } lifetimeScope;
static const char* toString(MoveKind moveKind);

40
test/testautovariables.cpp
View File

@ -2222,6 +2222,46 @@ private:
" std::sort(x.begin(), x.end());\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("struct A {\n"
" std::vector<int*> v;\n"
" void add(int* i) {\n"
" v.push_back(i);\n"
" }\n"
" void f() {\n"
" int i = 0;\n"
" add(&i);\n"
" }\n"
"};\n");
ASSERT_EQUALS(
"[test.cpp:8] -> [test.cpp:8] -> [test.cpp:4] -> [test.cpp:7] -> [test.cpp:4]: (error) Non-local variable 'v' will use object that points to local variable 'i'.\n",
errout.str());
check("struct A {\n"
" std::vector<int*> v;\n"
" void add(int* i) {\n"
" v.push_back(i);\n"
" }\n"
"};\n"
"void f() {\n"
" A a;\n"
" int i = 0;\n"
" a.add(&i);\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("struct A {\n"
" std::vector<int*> v;\n"
" void add(int* i) {\n"
" v.push_back(i);\n"
" }\n"
" void f() {\n"
" A a;\n"
" int i = 0;\n"
" a.add(&i);\n"
" }\n"
"};\n");
ASSERT_EQUALS("", errout.str());
}
void danglingLifetime() {