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Fix issue 9587: False positive: parameter can be declared with const (#2667)

This commit is contained in:
Paul Fultz II 2020-05-31 03:10:10 -05:00 committed by GitHub
parent 0a6150ae1c
commit eb4754b7d9
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GPG Key ID: 4AEE18F83AFDEB23
9 changed files with 99 additions and 47 deletions
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18
lib/astutils.cpp
View File

@ -344,6 +344,22 @@ const Token* getParentMember(const Token * tok)
return tok;
}
const Token* getParentLifetime(const Token* tok)
{
if (!tok)
return tok;
const Variable* var = tok->variable();
// TODO: Call getLifetimeVariable for deeper analysis
if (!var)
return tok;
if (var->isLocal() || var->isArgument())
return tok;
const Token* parent = getParentMember(tok);
if (parent != tok)
return getParentLifetime(parent);
return tok;
}
bool astIsLHS(const Token* tok)
{
if (!tok)
@ -448,8 +464,6 @@ bool isAliasOf(const Token *tok, nonneg int varid)
{
if (tok->varId() == varid)
return false;
if (tok->varId() == 0)
return false;
for (const ValueFlow::Value &val : tok->values()) {
if (!val.isLocalLifetimeValue())
continue;

2
lib/astutils.h
View File

@ -97,6 +97,8 @@ const Token* astParentSkipParens(const Token* tok);
const Token* getParentMember(const Token * tok);
const Token* getParentLifetime(const Token* tok);
bool astIsLHS(const Token* tok);
bool astIsRHS(const Token* tok);

16
lib/checkautovariables.cpp
View File

@ -432,22 +432,6 @@ static bool isDeadScope(const Token * tok, const Scope * scope)
return false;
}
static const Token * getParentLifetime(const Token *tok)
{
if (!tok)
return tok;
const Variable * var = tok->variable();
// TODO: Call getLifetimeVariable for deeper analysis
if (!var)
return tok;
if (var->isLocal())
return tok;
const Token * parent = getParentMember(tok);
if (parent != tok)
return getParentLifetime(parent);
return tok;
}
static int getPointerDepth(const Token *tok)
{
if (!tok)

16
lib/checkother.cpp
View File

@ -31,6 +31,7 @@
#include "token.h"
#include "tokenize.h"
#include "utils.h"
#include "valueflow.h"
#include <algorithm> // find_if()
#include <list>
@ -1363,9 +1364,20 @@ void CheckOther::checkConstVariable()
continue;
if (isVariableChanged(var, mSettings, mTokenizer->isCPP()))
continue;
if (Function::returnsReference(function) &&
Token::findmatch(var->nameToken(), "return %varid% ;|[|.", scope->bodyEnd, var->declarationId()))
if (Function::returnsReference(function)) {
std::vector<const Token*> returns = Function::findReturns(function);
if (std::any_of(returns.begin(), returns.end(), [&](const Token* retTok) {
if (retTok->varId() == var->declarationId())
return true;
while (Token::simpleMatch(retTok, "."))
retTok = retTok->astOperand2();
const Variable* retVar = getLifetimeVariable(getParentLifetime(retTok));
if (!retVar)
return false;
return retVar->declarationId() == var->declarationId();
}))
continue;
}
// Skip if address is taken
if (Token::findmatch(var->nameToken(), "& %varid%", scope->bodyEnd, var->declarationId()))
continue;

26
lib/symboldatabase.cpp
View File

@ -2439,6 +2439,32 @@ bool Function::returnsReference(const Function* function, bool unknown)
return false;
}
std::vector<const Token*> Function::findReturns(const Function* f)
{
std::vector<const Token*> result;
if (!f)
return result;
const Scope* scope = f->functionScope;
if (!scope)
return result;
for (const Token* tok = scope->bodyStart->next(); tok && tok != scope->bodyEnd; tok = tok->next()) {
if (tok->str() == "{" && tok->scope() &&
(tok->scope()->type == Scope::eLambda || tok->scope()->type == Scope::eClass)) {
tok = tok->link();
continue;
}
if (Token::simpleMatch(tok->astParent(), "return")) {
result.push_back(tok);
}
// Skip lambda functions since the scope may not be set correctly
const Token* lambdaEndToken = findLambdaEndToken(tok);
if (lambdaEndToken) {
tok = lambdaEndToken;
}
}
return result;
}
const Token * Function::constructorMemberInitialization() const
{
if (!isConstructor() || !functionScope || !functionScope->bodyStart)

2
lib/symboldatabase.h
View File

@ -896,6 +896,8 @@ public:
static bool returnsReference(const Function* function, bool unknown = false);
static std::vector<const Token*> findReturns(const Function* f);
const Token* returnDefEnd() const {
if (this->hasTrailingReturnType()) {
return Token::findmatch(retDef, "{|;");

44
lib/valueflow.cpp
View File

@ -2718,30 +2718,6 @@ static void valueFlowForward(Token* startToken,
}
}
static std::vector<const Token*> findReturns(const Function* f)
{
std::vector<const Token*> result;
const Scope* scope = f->functionScope;
if (!scope)
return result;
for (const Token* tok = scope->bodyStart->next(); tok && tok != scope->bodyEnd; tok = tok->next()) {
if (tok->str() == "{" && tok->scope() &&
(tok->scope()->type == Scope::eLambda || tok->scope()->type == Scope::eClass)) {
tok = tok->link();
continue;
}
if (Token::simpleMatch(tok->astParent(), "return")) {
result.push_back(tok);
}
// Skip lambda functions since the scope may not be set correctly
const Token* lambdaEndToken = findLambdaEndToken(tok);
if (lambdaEndToken) {
tok = lambdaEndToken;
}
}
return result;
}
static int getArgumentPos(const Variable *var, const Function *f)
{
auto arg_it = std::find_if(f->argumentList.begin(), f->argumentList.end(), [&](const Variable &v) {
@ -2850,6 +2826,16 @@ std::vector<LifetimeToken> getLifetimeTokens(const Token* tok, ValueFlow::Value:
return {{tok, true, std::move(errorPath)}};
if (vartok)
return getLifetimeTokens(vartok, std::move(errorPath), depth - 1);
} else if (Token::simpleMatch(var->nameToken()->astParent(), ":") &&
var->nameToken()->astParent()->astParent() &&
Token::simpleMatch(var->nameToken()->astParent()->astParent()->previous(), "for (")) {
errorPath.emplace_back(var->nameToken(), "Assigned to reference.");
const Token* vartok = var->nameToken();
if (vartok == tok)
return {{tok, true, std::move(errorPath)}};
const Token* contok = var->nameToken()->astParent()->astOperand2();
if (contok)
return getLifetimeTokens(contok, std::move(errorPath), depth - 1);
} else {
return std::vector<LifetimeToken> {};
}
@ -2860,7 +2846,7 @@ std::vector<LifetimeToken> getLifetimeTokens(const Token* tok, ValueFlow::Value:
if (!Function::returnsReference(f))
return {{tok, std::move(errorPath)}};
std::vector<LifetimeToken> result;
std::vector<const Token*> returns = findReturns(f);
std::vector<const Token*> returns = Function::findReturns(f);
for (const Token* returnTok : returns) {
if (returnTok == tok)
continue;
@ -2947,6 +2933,12 @@ const Variable* getLifetimeVariable(const Token* tok, ValueFlow::Value::ErrorPat
return nullptr;
}
const Variable* getLifetimeVariable(const Token* tok)
{
ValueFlow::Value::ErrorPath errorPath;
return getLifetimeVariable(tok, errorPath, nullptr);
}
static bool isNotLifetimeValue(const ValueFlow::Value& val)
{
return !val.isLifetimeValue();
@ -3394,7 +3386,7 @@ static void valueFlowLifetimeFunction(Token *tok, TokenList *tokenlist, ErrorLog
const Function *f = tok->function();
if (Function::returnsReference(f))
return;
std::vector<const Token*> returns = findReturns(f);
std::vector<const Token*> returns = Function::findReturns(f);
const bool inconclusive = returns.size() > 1;
for (const Token* returnTok : returns) {
if (returnTok == tok)

2
lib/valueflow.h
View File

@ -359,6 +359,8 @@ std::vector<LifetimeToken> getLifetimeTokens(const Token* tok, ValueFlow::Value:
const Variable* getLifetimeVariable(const Token* tok, ValueFlow::Value::ErrorPath& errorPath, bool* addressOf = nullptr);
const Variable* getLifetimeVariable(const Token* tok);
bool isLifetimeBorrowed(const Token *tok, const Settings *settings);
std::string lifetimeType(const Token *tok, const ValueFlow::Value *val);

18
test/testother.cpp
View File

@ -1959,6 +1959,24 @@ private:
"}\n");
ASSERT_EQUALS("", errout.str());
check("int* f(std::list<int>& x, unsigned int y) {\n"
" for (int& m : x) {\n"
" if (m == y)\n"
" return &m;\n"
" }\n"
" return nullptr;\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("int& f(std::list<int>& x, int& y) {\n"
" for (int& m : x) {\n"
" if (m == y)\n"
" return m;\n"
" }\n"
" return y;\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("void e();\n"
"void g(void);\n"
"void h(void);\n"