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cppcheck/lib/checkunusedvar.cpp

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/*
* Cppcheck - A tool for static C/C++ code analysis
* Copyright (C) 2007-2011 Daniel Marjamäki and Cppcheck team.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
//---------------------------------------------------------------------------
#include "checkunusedvar.h"
#include "symboldatabase.h"
//---------------------------------------------------------------------------
// Register this check class (by creating a static instance of it)
namespace {
CheckUnusedVar instance;
}
/**
* @brief This class is used to capture the control flow within a function.
*/
class ScopeInfo {
public:
ScopeInfo() : _token(NULL), _parent(NULL) { }
ScopeInfo(const Token *token, ScopeInfo *parent_) : _token(token), _parent(parent_) { }
~ScopeInfo();
ScopeInfo *parent() {
return _parent;
}
ScopeInfo *addChild(const Token *token);
void remove(ScopeInfo *scope);
private:
const Token *_token;
ScopeInfo *_parent;
std::list<ScopeInfo *> _children;
};
ScopeInfo::~ScopeInfo()
{
while (!_children.empty()) {
delete *_children.begin();
_children.pop_front();
}
}
ScopeInfo *ScopeInfo::addChild(const Token *token)
{
ScopeInfo *temp = new ScopeInfo(token, this);
_children.push_back(temp);
return temp;
}
void ScopeInfo::remove(ScopeInfo *scope)
{
std::list<ScopeInfo *>::iterator it;
for (it = _children.begin(); it != _children.end(); ++it) {
if (*it == scope) {
delete *it;
_children.erase(it);
break;
}
}
}
/**
* @brief This class is used create a list of variables within a function.
*/
class Variables {
public:
enum VariableType { standard, array, pointer, reference, pointerArray, referenceArray, pointerPointer };
/** Store information about variable usage */
class VariableUsage {
public:
VariableUsage(const Token *name = 0,
VariableType type = standard,
ScopeInfo *scope = NULL,
bool read = false,
bool write = false,
bool modified = false,
bool allocateMemory = false) :
_name(name),
_type(type),
_scope(scope),
_read(read),
_write(write),
_modified(modified),
_allocateMemory(allocateMemory) {
}
/** variable is used.. set both read+write */
void use() {
_read = true;
_write = true;
}
/** is variable unused? */
bool unused() const {
return (_read == false && _write == false);
}
const Token *_name;
VariableType _type;
ScopeInfo *_scope;
bool _read;
bool _write;
bool _modified; // read/modify/write
bool _allocateMemory;
std::set<unsigned int> _aliases;
std::set<ScopeInfo *> _assignments;
};
typedef std::map<unsigned int, VariableUsage> VariableMap;
void clear() {
_varUsage.clear();
}
VariableMap &varUsage() {
return _varUsage;
}
void addVar(const Token *name, VariableType type, ScopeInfo *scope, bool write_);
void allocateMemory(unsigned int varid);
void read(unsigned int varid);
void readAliases(unsigned int varid);
void readAll(unsigned int varid);
void write(unsigned int varid);
void writeAliases(unsigned int varid);
void writeAll(unsigned int varid);
void use(unsigned int varid);
void modified(unsigned int varid);
VariableUsage *find(unsigned int varid);
void alias(unsigned int varid1, unsigned int varid2, bool replace);
void erase(unsigned int varid) {
_varUsage.erase(varid);
}
void eraseAliases(unsigned int varid);
void eraseAll(unsigned int varid);
void clearAliases(unsigned int varid);
private:
VariableMap _varUsage;
};
/**
* Alias the 2 given variables. Either replace the existing aliases if
* they exist or merge them. You would replace an existing alias when this
* assignment is in the same scope as the previous assignment. You might
* merge the aliases when this assignment is in a different scope from the
* previous assignment depending on the relationship of the 2 scopes.
*/
void Variables::alias(unsigned int varid1, unsigned int varid2, bool replace)
{
VariableUsage *var1 = find(varid1);
VariableUsage *var2 = find(varid2);
// alias to self
if (varid1 == varid2) {
if (var1)
var1->use();
return;
}
std::set<unsigned int>::iterator i;
if (replace) {
// remove var1 from all aliases
for (i = var1->_aliases.begin(); i != var1->_aliases.end(); ++i) {
VariableUsage *temp = find(*i);
if (temp)
temp->_aliases.erase(var1->_name->varId());
}
// remove all aliases from var1
var1->_aliases.clear();
}
// var1 gets all var2s aliases
for (i = var2->_aliases.begin(); i != var2->_aliases.end(); ++i) {
if (*i != varid1)
var1->_aliases.insert(*i);
}
// var2 is an alias of var1
var2->_aliases.insert(varid1);
var1->_aliases.insert(varid2);
if (var2->_type == Variables::pointer)
var2->_read = true;
}
void Variables::clearAliases(unsigned int varid)
{
VariableUsage *usage = find(varid);
if (usage) {
// remove usage from all aliases
std::set<unsigned int>::iterator i;
for (i = usage->_aliases.begin(); i != usage->_aliases.end(); ++i) {
VariableUsage *temp = find(*i);
if (temp)
temp->_aliases.erase(usage->_name->varId());
}
// remove all aliases from usage
usage->_aliases.clear();
}
}
void Variables::eraseAliases(unsigned int varid)
{
VariableUsage *usage = find(varid);
if (usage) {
std::set<unsigned int>::iterator aliases;
for (aliases = usage->_aliases.begin(); aliases != usage->_aliases.end(); ++aliases)
erase(*aliases);
}
}
void Variables::eraseAll(unsigned int varid)
{
eraseAliases(varid);
erase(varid);
}
void Variables::addVar(const Token *name,
VariableType type,
ScopeInfo *scope,
bool write_)
{
if (name->varId() > 0)
_varUsage.insert(std::make_pair(name->varId(), VariableUsage(name, type, scope, false, write_, false)));
}
void Variables::allocateMemory(unsigned int varid)
{
VariableUsage *usage = find(varid);
if (usage)
usage->_allocateMemory = true;
}
void Variables::read(unsigned int varid)
{
VariableUsage *usage = find(varid);
if (usage)
usage->_read = true;
}
void Variables::readAliases(unsigned int varid)
{
VariableUsage *usage = find(varid);
if (usage) {
std::set<unsigned int>::iterator aliases;
for (aliases = usage->_aliases.begin(); aliases != usage->_aliases.end(); ++aliases) {
VariableUsage *aliased = find(*aliases);
if (aliased)
aliased->_read = true;
}
}
}
void Variables::readAll(unsigned int varid)
{
VariableUsage *usage = find(varid);
if (usage) {
usage->_read = true;
std::set<unsigned int>::iterator aliases;
for (aliases = usage->_aliases.begin(); aliases != usage->_aliases.end(); ++aliases) {
VariableUsage *aliased = find(*aliases);
if (aliased)
aliased->_read = true;
}
}
}
void Variables::write(unsigned int varid)
{
VariableUsage *usage = find(varid);
if (usage)
usage->_write = true;
}
void Variables::writeAliases(unsigned int varid)
{
VariableUsage *usage = find(varid);
if (usage) {
std::set<unsigned int>::iterator aliases;
for (aliases = usage->_aliases.begin(); aliases != usage->_aliases.end(); ++aliases) {
VariableUsage *aliased = find(*aliases);
if (aliased)
aliased->_write = true;
}
}
}
void Variables::writeAll(unsigned int varid)
{
VariableUsage *usage = find(varid);
if (usage) {
usage->_write = true;
std::set<unsigned int>::iterator aliases;
for (aliases = usage->_aliases.begin(); aliases != usage->_aliases.end(); ++aliases) {
VariableUsage *aliased = find(*aliases);
if (aliased)
aliased->_write = true;
}
}
}
void Variables::use(unsigned int varid)
{
VariableUsage *usage = find(varid);
if (usage) {
usage->use();
std::set<unsigned int>::iterator aliases;
for (aliases = usage->_aliases.begin(); aliases != usage->_aliases.end(); ++aliases) {
VariableUsage *aliased = find(*aliases);
if (aliased)
aliased->use();
}
}
}
void Variables::modified(unsigned int varid)
{
VariableUsage *usage = find(varid);
if (usage) {
usage->_modified = true;
std::set<unsigned int>::iterator aliases;
for (aliases = usage->_aliases.begin(); aliases != usage->_aliases.end(); ++aliases) {
VariableUsage *aliased = find(*aliases);
if (aliased)
aliased->_modified = true;
}
}
}
Variables::VariableUsage *Variables::find(unsigned int varid)
{
if (varid) {
VariableMap::iterator i = _varUsage.find(varid);
if (i != _varUsage.end())
return &i->second;
}
return 0;
}
static int doAssignment(Variables &variables, const Token *tok, bool dereference, ScopeInfo *scope)
{
int next = 0;
// a = a + b;
if (Token::Match(tok, "%var% = %var% !!;") && tok->str() == tok->strAt(2)) {
return 2;
}
// check for aliased variable
const unsigned int varid1 = tok->varId();
Variables::VariableUsage *var1 = variables.find(varid1);
if (var1) {
Variables::VariableUsage *var2 = 0;
int start = 1;
// search for '='
while (tok->tokAt(start)->str() != "=")
start++;
start++;
if (Token::Match(tok->tokAt(start), "&| %var%") ||
Token::Match(tok->tokAt(start), "( const| struct|union| %type% *| ) &| %var%") ||
Token::Match(tok->tokAt(start), "( const| struct|union| %type% *| ) ( &| %var%") ||
Token::Match(tok->tokAt(start), "%any% < const| struct|union| %type% *| > ( &| %var%")) {
unsigned char offset = 0;
unsigned int varid2;
bool addressOf = false;
if (Token::Match(tok->tokAt(start), "%var% ."))
variables.use(tok->tokAt(start)->varId()); // use = read + write
// check for C style cast
if (tok->tokAt(start)->str() == "(") {
if (tok->tokAt(start + 1)->str() == "const")
offset++;
if (Token::Match(tok->tokAt(start + 1 + offset), "struct|union"))
offset++;
if (tok->tokAt(start + 2 + offset)->str() == "*")
offset++;
if (tok->tokAt(start + 3 + offset)->str() == "&") {
addressOf = true;
next = start + 4 + offset;
} else if (tok->tokAt(start + 3 + offset)->str() == "(") {
if (tok->tokAt(start + 4 + offset)->str() == "&") {
addressOf = true;
next = start + 5 + offset;
} else
next = start + 4 + offset;
} else
next = start + 3 + offset;
}
// check for C++ style cast
else if (tok->tokAt(start)->str().find("cast") != std::string::npos &&
tok->tokAt(start + 1)->str() == "<") {
if (tok->tokAt(start + 2)->str() == "const")
offset++;
if (Token::Match(tok->tokAt(start + 2 + offset), "struct|union"))
offset++;
if (tok->tokAt(start + 3 + offset)->str() == "*")
offset++;
if (tok->tokAt(start + 5 + offset)->str() == "&") {
addressOf = true;
next = start + 6 + offset;
} else
next = start + 5 + offset;
}
// check for var ? ...
else if (Token::Match(tok->tokAt(start), "%var% ?")) {
next = start;
}
// no cast
else {
if (tok->tokAt(start)->str() == "&") {
addressOf = true;
next = start + 1;
} else if (tok->tokAt(start)->str() == "new")
return 0;
else
next = start;
}
// check if variable is local
varid2 = tok->tokAt(next)->varId();
var2 = variables.find(varid2);
if (var2) { // local variable (alias or read it)
if (var1->_type == Variables::pointer) {
if (dereference)
variables.read(varid2);
else {
if (addressOf ||
var2->_type == Variables::array ||
var2->_type == Variables::pointer) {
bool replace = true;
// check if variable declared in same scope
if (scope == var1->_scope)
replace = true;
// not in same scope as declaration
else {
std::set<ScopeInfo *>::iterator assignment;
// check for an assignment in this scope
assignment = var1->_assignments.find(scope);
// no other assignment in this scope
if (assignment == var1->_assignments.end()) {
// nothing to replace
if (var1->_assignments.empty())
replace = false;
// this variable has previous assignments
else {
/**
* @todo determine if existing aliases should be replaced or merged
*/
replace = false;
}
}
// assignment in this scope
else {
// replace when only one other assignment
if (var1->_assignments.size() == 1)
replace = true;
// otherwise, merge them
else
replace = false;
}
}
variables.alias(varid1, varid2, replace);
} else if (tok->tokAt(next + 1)->str() == "?") {
if (var2->_type == Variables::reference)
variables.readAliases(varid2);
else
variables.read(varid2);
}
}
} else if (var1->_type == Variables::reference) {
variables.alias(varid1, varid2, true);
} else {
if (var2->_type == Variables::pointer && tok->tokAt(next + 1)->str() == "[")
variables.readAliases(varid2);
variables.read(varid2);
}
} else { // not a local variable (or an unsupported local variable)
if (var1->_type == Variables::pointer && !dereference) {
// check if variable declaration is in this scope
if (var1->_scope == scope)
variables.clearAliases(varid1);
else {
std::set<ScopeInfo *>::iterator assignment;
// check for an assignment in this scope
assignment = var1->_assignments.find(scope);
// no other assignment in this scope
if (assignment == var1->_assignments.end()) {
/**
* @todo determine if existing aliases should be discarded
*/
}
// this assignment replaces the last assignment in this scope
else {
// aliased variables in a larger scope are not supported
// remove all aliases
variables.clearAliases(varid1);
}
}
}
}
}
var1->_assignments.insert(scope);
}
// check for alias to struct member
// char c[10]; a.b = c;
else if (Token::Match(tok->tokAt(-2), "%var% .")) {
if (Token::Match(tok->tokAt(2), "%var%")) {
unsigned int varid2 = tok->tokAt(2)->varId();
Variables::VariableUsage *var2 = variables.find(varid2);
// struct member aliased to local variable
if (var2 && (var2->_type == Variables::array ||
var2->_type == Variables::pointer)) {
// erase aliased variable and all variables that alias it
// to prevent false positives
variables.eraseAll(varid2);
}
}
}
return next;
}
static bool nextIsStandardType(const Token *tok)
{
tok = tok->next();
if (tok->str() == "static")
tok = tok->next();
return tok->isStandardType();
}
static bool nextIsStandardTypeOrVoid(const Token *tok)
{
tok = tok->next();
if (tok->str() == "static")
tok = tok->next();
if (tok->str() == "const")
tok = tok->next();
return tok->isStandardType() || tok->str() == "void";
}
bool CheckUnusedVar::isRecordTypeWithoutSideEffects(const Token *tok)
{
const Variable * var = _tokenizer->getSymbolDatabase()->getVariableFromVarId(tok->varId());
// a type that has no side effects (no constructors and no members with constructors)
/** @todo false negative: check base class for side effects */
/** @todo false negative: check constructors for side effects */
if (var && var->type() && var->type()->numConstructors == 0 &&
(var->type()->varlist.empty() || var->type()->needInitialization == Scope::True) &&
var->type()->derivedFrom.empty())
return true;
return false;
}
//---------------------------------------------------------------------------
// Usage of function variables
//---------------------------------------------------------------------------
void CheckUnusedVar::checkFunctionVariableUsage()
{
if (!_settings->isEnabled("style"))
return;
// Parse all executing scopes..
const SymbolDatabase *symbolDatabase = _tokenizer->getSymbolDatabase();
std::list<Scope>::const_iterator scope;
for (scope = symbolDatabase->scopeList.begin(); scope != symbolDatabase->scopeList.end(); ++scope) {
// only check functions
if (scope->type != Scope::eFunction)
continue;
// First token for the current scope..
const Token *const tok1 = scope->classStart;
// varId, usage {read, write, modified}
Variables variables;
// scopes
ScopeInfo scopes;
ScopeInfo *info = &scopes;
unsigned int indentlevel = 0;
for (const Token *tok = tok1; tok; tok = tok->next()) {
if (tok->str() == "{") {
// replace the head node when found
if (indentlevel == 0)
scopes = ScopeInfo(tok, NULL);
// add the new scope
else
info = info->addChild(tok);
++indentlevel;
} else if (tok->str() == "}") {
--indentlevel;
info = info->parent();
if (indentlevel == 0)
break;
} else if (Token::Match(tok, "struct|union|class {") ||
Token::Match(tok, "struct|union|class %type% {|:")) {
while (tok->str() != "{")
tok = tok->next();
tok = tok->link();
if (! tok)
break;
}
if (Token::Match(tok, "[;{}] asm ( ) ;")) {
variables.clear();
break;
}
// standard type declaration with possible initialization
// int i; int j = 0; static int k;
if (Token::Match(tok, "[;{}] static| %type% %var% ;|=") &&
!Token::Match(tok->next(), "return|throw")) {
tok = tok->next();
const bool isStatic = tok->str() == "static";
if (isStatic)
tok = tok->next();
if (tok->isStandardType() || isRecordTypeWithoutSideEffects(tok->next())) {
variables.addVar(tok->next(), Variables::standard, info,
tok->tokAt(2)->str() == "=" || isStatic);
}
tok = tok->next();
}
// standard const type declaration
// const int i = x;
else if (Token::Match(tok, "[;{}] const %type% %var% =")) {
tok = tok->next()->next();
if (tok->isStandardType() || isRecordTypeWithoutSideEffects(tok->next()))
variables.addVar(tok->next(), Variables::standard, info, true);
tok = tok->next();
}
// std::string declaration with possible initialization
// std::string s; std::string s = "string";
else if (Token::Match(tok, "[;{}] static| std :: string %var% ;|=")) {
tok = tok->next();
const bool isStatic = tok->str() == "static";
if (isStatic)
tok = tok->next();
tok = tok->tokAt(3);
variables.addVar(tok, Variables::standard, info,
tok->next()->str() == "=" || isStatic);
}
// standard struct type declaration with possible initialization
// struct S s; struct S s = { 0 }; static struct S s;
else if (Token::Match(tok, "[;{}] static| struct %type% %var% ;|=") &&
(isRecordTypeWithoutSideEffects(tok->strAt(1) == "static" ? tok->tokAt(4) : tok->tokAt(3)))) {
tok = tok->next();
bool isStatic = tok->str() == "static";
if (isStatic)
tok = tok->next();
tok = tok->next();
variables.addVar(tok->next(), Variables::standard, info,
tok->tokAt(2)->str() == "=" || isStatic);
tok = tok->next();
}
// standard type declaration and initialization using constructor
// int i(0); static int j(0);
else if (Token::Match(tok, "[;{}] static| %type% %var% ( %any% ) ;") &&
nextIsStandardType(tok)) {
tok = tok->next();
if (tok->str() == "static")
tok = tok->next();
variables.addVar(tok->next(), Variables::standard, info, true);
// check if a local variable is used to initialize this variable
if (tok->tokAt(3)->varId() > 0)
variables.readAll(tok->tokAt(3)->varId());
tok = tok->tokAt(4);
}
// standard type declaration of array of with possible initialization
// int i[10]; int j[2] = { 0, 1 }; static int k[2] = { 2, 3 };
else if (Token::Match(tok, "[;{}] static| const| %type% *| %var% [ %any% ] ;|=") &&
nextIsStandardType(tok)) {
tok = tok->next();
const bool isStatic = tok->str() == "static";
if (isStatic)
tok = tok->next();
if (tok->str() == "const")
tok = tok->next();
if (tok->str() != "return" && tok->str() != "throw") {
bool isPointer = bool(tok->strAt(1) == "*");
const Token * const nametok = tok->tokAt(isPointer ? 2 : 1);
variables.addVar(nametok, isPointer ? Variables::pointerArray : Variables::array, info,
nametok->tokAt(4)->str() == "=" || isStatic);
// check for reading array size from local variable
if (nametok->tokAt(2)->varId() != 0)
variables.read(nametok->tokAt(2)->varId());
// look at initializers
if (Token::simpleMatch(nametok->tokAt(4), "= {")) {
tok = nametok->tokAt(6);
while (tok->str() != "}") {
if (Token::Match(tok, "%var%"))
variables.read(tok->varId());
tok = tok->next();
}
} else
tok = nametok->tokAt(3);
}
}
// pointer or reference declaration with possible initialization
// int * i; int * j = 0; static int * k = 0;
else if (Token::Match(tok, "[;{}] static| const| %type% *|& %var% ;|=")) {
tok = tok->next();
const bool isStatic = tok->str() == "static";
if (isStatic)
tok = tok->next();
if (tok->str() == "const")
tok = tok->next();
if (tok->strAt(1) == "::")
tok = tok->tokAt(2);
if (tok->str() != "return" && tok->str() != "throw") {
Variables::VariableType type;
if (tok->next()->str() == "*")
type = Variables::pointer;
else
type = Variables::reference;
bool written = tok->tokAt(3)->str() == "=";
variables.addVar(tok->tokAt(2), type, info, written || isStatic);
int offset = 0;
// check for assignment
if (written)
offset = doAssignment(variables, tok->tokAt(2), false, info);
tok = tok->tokAt(2 + offset);
}
}
// pointer to pointer declaration with possible initialization
// int ** i; int ** j = 0; static int ** k = 0;
else if (Token::Match(tok, "[;{}] static| const| %type% * * %var% ;|=")) {
tok = tok->next();
const bool isStatic = tok->str() == "static";
if (isStatic)
tok = tok->next();
if (tok->str() == "const")
tok = tok->next();
if (tok->str() != "return") {
bool written = tok->tokAt(4)->str() == "=";
variables.addVar(tok->tokAt(3), Variables::pointerPointer, info, written || isStatic);
int offset = 0;
// check for assignment
if (written)
offset = doAssignment(variables, tok->tokAt(3), false, info);
tok = tok->tokAt(3 + offset);
}
}
// pointer or reference of struct or union declaration with possible initialization
// struct s * i; struct s * j = 0; static struct s * k = 0;
else if (Token::Match(tok, "[;{}] static| const| struct|union %type% *|& %var% ;|=")) {
Variables::VariableType type;
tok = tok->next();
const bool isStatic = tok->str() == "static";
if (isStatic)
tok = tok->next();
if (tok->str() == "const")
tok = tok->next();
if (tok->strAt(2) == "*")
type = Variables::pointer;
else
type = Variables::reference;
const bool written = tok->strAt(4) == "=";
variables.addVar(tok->tokAt(3), type, info, written || isStatic);
int offset = 0;
// check for assignment
if (written)
offset = doAssignment(variables, tok->tokAt(3), false, info);
tok = tok->tokAt(3 + offset);
}
// pointer or reference declaration with initialization using constructor
// int * i(j); int * k(i); static int * l(i);
else if (Token::Match(tok, "[;{}] static| const| %type% &|* %var% ( %any% ) ;") &&
nextIsStandardTypeOrVoid(tok)) {
Variables::VariableType type;
tok = tok->next();
if (tok->str() == "static")
tok = tok->next();
if (tok->str() == "const")
tok = tok->next();
if (tok->next()->str() == "*")
type = Variables::pointer;
else
type = Variables::reference;
unsigned int varid = 0;
// check for aliased variable
if (Token::Match(tok->tokAt(4), "%var%"))
varid = tok->tokAt(4)->varId();
variables.addVar(tok->tokAt(2), type, info, true);
// check if a local variable is used to initialize this variable
if (varid > 0) {
Variables::VariableUsage *var = variables.find(varid);
if (type == Variables::pointer) {
variables.use(tok->tokAt(4)->varId());
if (var && (var->_type == Variables::array ||
var->_type == Variables::pointer))
var->_aliases.insert(tok->varId());
} else {
variables.readAll(tok->tokAt(4)->varId());
if (var)
var->_aliases.insert(tok->varId());
}
}
tok = tok->tokAt(5);
}
// array of pointer or reference declaration with possible initialization
// int * p[10]; int * q[10] = { 0 }; static int * * r[10] = { 0 };
else if (Token::Match(tok, "[;{}] static| const| %type% *|& %var% [ %any% ] ;|=")) {
tok = tok->next();
const bool isStatic = tok->str() == "static";
if (isStatic)
tok = tok->next();
if (tok->str() == "const")
tok = tok->next();
if (tok->str() != "return") {
variables.addVar(tok->tokAt(2),
tok->next()->str() == "*" ? Variables::pointerArray : Variables::referenceArray, info,
tok->tokAt(6)->str() == "=" || isStatic);
// check for reading array size from local variable
if (tok->tokAt(4)->varId() != 0)
variables.read(tok->tokAt(4)->varId());
tok = tok->tokAt(5);
}
}
// array of pointer or reference of struct or union declaration with possible initialization
// struct S * p[10]; struct T * q[10] = { 0 }; static struct S * r[10] = { 0 };
else if (Token::Match(tok, "[;{}] static| const| struct|union %type% *|& %var% [ %any% ] ;|=")) {
tok = tok->next();
const bool isStatic = tok->str() == "static";
if (isStatic)
tok = tok->next();
if (tok->str() == "const")
tok = tok->next();
variables.addVar(tok->tokAt(3),
tok->tokAt(2)->str() == "*" ? Variables::pointerArray : Variables::referenceArray, info,
tok->tokAt(7)->str() == "=" || isStatic);
// check for reading array size from local variable
if (tok->tokAt(5)->varId() != 0)
variables.read(tok->tokAt(5)->varId());
tok = tok->tokAt(6);
}
// Freeing memory (not considered "using" the pointer if it was also allocated in this function)
else if (Token::Match(tok, "free|g_free|kfree|vfree ( %var% )") ||
Token::Match(tok, "delete %var% ;") ||
Token::Match(tok, "delete [ ] %var% ;")) {
unsigned int varid = 0;
if (tok->str() != "delete") {
varid = tok->tokAt(2)->varId();
tok = tok->tokAt(3);
} else if (tok->strAt(1) == "[") {
varid = tok->tokAt(3)->varId();
tok = tok->tokAt(4);
} else {
varid = tok->next()->varId();
tok = tok->tokAt(2);
}
Variables::VariableUsage *var = variables.find(varid);
if (var && !var->_allocateMemory) {
variables.readAll(varid);
}
}
else if (Token::Match(tok, "return|throw %var%"))
variables.readAll(tok->next()->varId());
// assignment
else if (!Token::Match(tok->tokAt(-2), "[;{}.] %var% (") &&
(Token::Match(tok, "*| (| ++|--| %var% ++|--| )| =") ||
Token::Match(tok, "*| ( const| %type% *| ) %var% ="))) {
bool dereference = false;
bool pre = false;
bool post = false;
if (tok->str() == "*") {
dereference = true;
tok = tok->next();
}
if (Token::Match(tok, "( const| %type% *| ) %var% ="))
tok = tok->link()->next();
else if (tok->str() == "(")
tok = tok->next();
if (Token::Match(tok, "++|--")) {
pre = true;
tok = tok->next();
}
if (Token::Match(tok->next(), "++|--"))
post = true;
const unsigned int varid1 = tok->varId();
const Token *start = tok;
tok = tok->tokAt(doAssignment(variables, tok, dereference, info));
if (pre || post)
variables.use(varid1);
if (dereference) {
Variables::VariableUsage *var = variables.find(varid1);
if (var && var->_type == Variables::array)
variables.write(varid1);
variables.writeAliases(varid1);
variables.read(varid1);
} else {
Variables::VariableUsage *var = variables.find(varid1);
if (var && var->_type == Variables::reference) {
variables.writeAliases(varid1);
variables.read(varid1);
}
// Consider allocating memory separately because allocating/freeing alone does not constitute using the variable
else if (var && var->_type == Variables::pointer &&
Token::Match(start, "%var% = new|malloc|calloc|g_malloc|kmalloc|vmalloc")) {
bool allocate = true;
if (start->strAt(2) == "new") {
const Token *type = start->tokAt(3);
// skip nothrow
if (Token::simpleMatch(type, "( nothrow )") ||
Token::simpleMatch(type, "( std :: nothrow )"))
type = type->link()->next();
// is it a user defined type?
if (!type->isStandardType()) {
if (!isRecordTypeWithoutSideEffects(start))
allocate = false;
}
}
if (allocate)
variables.allocateMemory(varid1);
else
variables.write(varid1);
} else if (varid1 && Token::Match(tok, "%varid% .", varid1)) {
variables.use(varid1);
} else {
variables.write(varid1);
}
Variables::VariableUsage *var2 = variables.find(tok->varId());
if (var2) {
if (var2->_type == Variables::reference) {
variables.writeAliases(tok->varId());
variables.read(tok->varId());
} else if (tok->varId() != varid1 && Token::Match(tok, "%var% ."))
variables.read(tok->varId());
else if (tok->varId() != varid1 &&
var2->_type == Variables::standard &&
tok->strAt(-1) != "&")
variables.use(tok->varId());
}
}
const Token *equal = tok->next();
if (Token::Match(tok->next(), "[ %any% ]"))
equal = tok->tokAt(4);
// checked for chained assignments
if (tok != start && equal->str() == "=") {
Variables::VariableUsage *var = variables.find(tok->varId());
if (var && var->_type != Variables::reference)
var->_read = true;
tok = tok->previous();
}
}
// assignment
else if (Token::Match(tok, "%var% [") && Token::simpleMatch(tok->next()->link(), "] =")) {
unsigned int varid = tok->varId();
const Variables::VariableUsage *var = variables.find(varid);
if (var) {
// Consider allocating memory separately because allocating/freeing alone does not constitute using the variable
if (var->_type == Variables::pointer &&
Token::Match(tok->next()->link(), "] = new|malloc|calloc|g_malloc|kmalloc|vmalloc")) {
variables.allocateMemory(varid);
} else if (var->_type == Variables::pointer || var->_type == Variables::reference) {
variables.read(varid);
variables.writeAliases(varid);
} else
variables.writeAll(varid);
}
}
else if (Token::Match(tok, ">>|& %var%"))
variables.use(tok->next()->varId()); // use = read + write
else if (Token::Match(tok, "[;{}] %var% >>"))
variables.use(tok->next()->varId()); // use = read + write
// function parameter
else if (Token::Match(tok, "[(,] %var% ["))
variables.use(tok->next()->varId()); // use = read + write
else if (Token::Match(tok, "[(,] %var% [,)]") && tok->previous()->str() != "*")
variables.use(tok->next()->varId()); // use = read + write
else if (Token::Match(tok, "[(,] (") &&
Token::Match(tok->next()->link(), ") %var% [,)]"))
variables.use(tok->next()->link()->next()->varId()); // use = read + write
// function
else if (Token::Match(tok, "%var% (")) {
variables.read(tok->varId());
if (Token::Match(tok->tokAt(2), "%var% ="))
variables.read(tok->tokAt(2)->varId());
}
else if (Token::Match(tok, "[{,] %var% [,}]"))
variables.read(tok->next()->varId());
else if (Token::Match(tok, "%var% ."))
variables.use(tok->varId()); // use = read + write
else if ((Token::Match(tok, "[(=&!]") || tok->isExtendedOp()) &&
(Token::Match(tok->next(), "%var%") && !Token::Match(tok->next(), "true|false|new")))
variables.readAll(tok->next()->varId());
else if (Token::Match(tok, "%var%") && (tok->next()->str() == ")" || tok->next()->isExtendedOp()))
variables.readAll(tok->varId());
else if (Token::Match(tok, "; %var% ;"))
variables.readAll(tok->next()->varId());
else if (Token::Match(tok, "++|-- %var%")) {
if (tok->strAt(-1) != ";")
variables.use(tok->next()->varId());
else
variables.modified(tok->next()->varId());
}
else if (Token::Match(tok, "%var% ++|--")) {
if (tok->strAt(-1) != ";")
variables.use(tok->varId());
else
variables.modified(tok->varId());
}
else if (tok->isAssignmentOp()) {
for (const Token *tok2 = tok->next(); tok2 && tok2->str() != ";"; tok2 = tok2->next()) {
if (tok2->varId()) {
variables.read(tok2->varId());
if (tok2->next()->isAssignmentOp())
variables.write(tok2->varId());
}
}
}
}
// Check usage of all variables in the current scope..
Variables::VariableMap::const_iterator it;
for (it = variables.varUsage().begin(); it != variables.varUsage().end(); ++it) {
const Variables::VariableUsage &usage = it->second;
const std::string &varname = usage._name->str();
// variable has been marked as unused so ignore it
if (usage._name->isUnused())
continue;
// skip things that are only partially implemented to prevent false positives
if (usage._type == Variables::pointerPointer ||
usage._type == Variables::pointerArray ||
usage._type == Variables::referenceArray)
continue;
// variable has had memory allocated for it, but hasn't done
// anything with that memory other than, perhaps, freeing it
if (usage.unused() && !usage._modified && usage._allocateMemory)
allocatedButUnusedVariableError(usage._name, varname);
// variable has not been written, read, or modified
else if (usage.unused() && !usage._modified)
unusedVariableError(usage._name, varname);
// variable has not been written but has been modified
else if (usage._modified & !usage._write)
unassignedVariableError(usage._name, varname);
// variable has been written but not read
else if (!usage._read && !usage._modified)
unreadVariableError(usage._name, varname);
// variable has been read but not written
else if (!usage._write && !usage._allocateMemory)
unassignedVariableError(usage._name, varname);
}
}
}
void CheckUnusedVar::unusedVariableError(const Token *tok, const std::string &varname)
{
reportError(tok, Severity::style, "unusedVariable", "Unused variable: " + varname);
}
void CheckUnusedVar::allocatedButUnusedVariableError(const Token *tok, const std::string &varname)
{
reportError(tok, Severity::style, "unusedAllocatedMemory", "Variable '" + varname + "' is allocated memory that is never used");
}
void CheckUnusedVar::unreadVariableError(const Token *tok, const std::string &varname)
{
reportError(tok, Severity::style, "unreadVariable", "Variable '" + varname + "' is assigned a value that is never used");
}
void CheckUnusedVar::unassignedVariableError(const Token *tok, const std::string &varname)
{
reportError(tok, Severity::style, "unassignedVariable", "Variable '" + varname + "' is not assigned a value");
}
//---------------------------------------------------------------------------
// Check that all struct members are used
//---------------------------------------------------------------------------
void CheckUnusedVar::checkStructMemberUsage()
{
if (!_settings->isEnabled("style"))
return;
std::string structname;
for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next()) {
if (tok->fileIndex() != 0)
continue;
if (Token::Match(tok, "struct|union %type% {")) {
structname.clear();
if (Token::simpleMatch(tok->previous(), "extern"))
continue;
if ((!tok->previous() || Token::simpleMatch(tok->previous(), ";")) && Token::Match(tok->tokAt(2)->link(), ("} ; " + tok->strAt(1) + " %var% ;").c_str()))
continue;
structname = tok->strAt(1);
// Bail out if struct/union contain any functions
for (const Token *tok2 = tok->tokAt(2); tok2; tok2 = tok2->next()) {
if (tok2->str() == "(") {
structname.clear();
break;
}
if (tok2->str() == "}")
break;
}
// bail out if struct is inherited
if (!structname.empty() && Token::findmatch(tok, (",|private|protected|public " + structname).c_str()))
structname.clear();
// Bail out if some data is casted to struct..
const std::string s("( struct| " + tok->next()->str() + " * ) & %var% [");
if (Token::findmatch(tok, s.c_str()))
structname.clear();
// Try to prevent false positives when struct members are not used directly.
if (Token::findmatch(tok, (structname + " *").c_str()))
structname.clear();
else if (Token::findmatch(tok, (structname + " %type% *").c_str()))
structname = "";
}
if (tok->str() == "}")
structname.clear();
if (!structname.empty() && Token::Match(tok, "[{;]")) {
// Declaring struct variable..
std::string varname;
// declaring a POD variable?
if (!tok->next()->isStandardType())
continue;
if (Token::Match(tok->next(), "%type% %var% [;[]"))
varname = tok->strAt(2);
else if (Token::Match(tok->next(), "%type% %type% %var% [;[]"))
varname = tok->strAt(3);
else if (Token::Match(tok->next(), "%type% * %var% [;[]"))
varname = tok->strAt(3);
else if (Token::Match(tok->next(), "%type% %type% * %var% [;[]"))
varname = tok->strAt(4);
else
continue;
// Check if the struct variable is used anywhere in the file
const std::string usagePattern(". " + varname);
bool used = false;
for (const Token *tok2 = _tokenizer->tokens(); tok2; tok2 = tok2->next()) {
if (Token::simpleMatch(tok2, usagePattern.c_str())) {
used = true;
break;
}
}
if (! used) {
unusedStructMemberError(tok->next(), structname, varname);
}
}
}
}
void CheckUnusedVar::unusedStructMemberError(const Token *tok, const std::string &structname, const std::string &varname)
{
reportError(tok, Severity::style, "unusedStructMember", "struct or union member '" + structname + "::" + varname + "' is never used");
}
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