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/*
* Cppcheck - A tool for static C/C++ code analysis
* Copyright (C) 2007-2012 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 create a list of variables within a function.
*/
class Variables {
public:
enum VariableType { standard, array, pointer, reference, pointerArray, referenceArray, pointerPointer, none };
/** Store information about variable usage */
class VariableUsage {
public:
VariableUsage(const Variable *var = 0,
VariableType type = standard,
bool read = false,
bool write = false,
bool modified = false,
bool allocateMemory = false) :
_var(var),
_lastAccess(var?var->nameToken():0),
_type(type),
_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);
}
std::set<unsigned int> _aliases;
std::set<const Scope*> _assignments;
const Variable* _var;
const Token* _lastAccess;
VariableType _type;
bool _read;
bool _write;
bool _modified; // read/modify/write
bool _allocateMemory;
};
typedef std::map<unsigned int, VariableUsage> VariableMap;
void clear() {
_varUsage.clear();
}
const VariableMap &varUsage() const {
return _varUsage;
}
void addVar(const Variable *var, VariableType type, bool write_);
void allocateMemory(unsigned int varid, const Token* tok);
void read(unsigned int varid, const Token* tok);
void readAliases(unsigned int varid, const Token* tok);
void readAll(unsigned int varid, const Token* tok);
void write(unsigned int varid, const Token* tok);
void writeAliases(unsigned int varid, const Token* tok);
void writeAll(unsigned int varid, const Token* tok);
void use(unsigned int varid, const Token* tok);
void modified(unsigned int varid, const Token* tok);
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;
}
if (replace) {
// remove var1 from all aliases
for (std::set<unsigned int>::iterator i = var1->_aliases.begin(); i != var1->_aliases.end(); ++i) {
VariableUsage *temp = find(*i);
if (temp)
temp->_aliases.erase(var1->_var->varId());
}
// remove all aliases from var1
var1->_aliases.clear();
}
// var1 gets all var2s aliases
for (std::set<unsigned int>::iterator 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->_var->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 Variable *var,
VariableType type,
bool write_)
{
if (var->varId() > 0)
_varUsage.insert(std::make_pair(var->varId(), VariableUsage(var, type, false, write_, false)));
}
void Variables::allocateMemory(unsigned int varid, const Token* tok)
{
VariableUsage *usage = find(varid);
if (usage) {
usage->_allocateMemory = true;
usage->_lastAccess = tok;
}
}
void Variables::read(unsigned int varid, const Token* tok)
{
VariableUsage *usage = find(varid);
if (usage) {
usage->_read = true;
usage->_lastAccess = tok;
}
}
void Variables::readAliases(unsigned int varid, const Token* tok)
{
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;
aliased->_lastAccess = tok;
}
}
}
}
void Variables::readAll(unsigned int varid, const Token* tok)
{
read(varid, tok);
readAliases(varid, tok);
}
void Variables::write(unsigned int varid, const Token* tok)
{
VariableUsage *usage = find(varid);
if (usage) {
usage->_write = true;
if (!usage->_var->isStatic())
usage->_read = false;
usage->_lastAccess = tok;
}
}
void Variables::writeAliases(unsigned int varid, const Token* tok)
{
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;
aliased->_lastAccess = tok;
}
}
}
}
void Variables::writeAll(unsigned int varid, const Token* tok)
{
write(varid, tok);
writeAliases(varid, tok);
}
void Variables::use(unsigned int varid, const Token* tok)
{
VariableUsage *usage = find(varid);
if (usage) {
usage->use();
usage->_lastAccess = tok;
std::set<unsigned int>::iterator aliases;
for (aliases = usage->_aliases.begin(); aliases != usage->_aliases.end(); ++aliases) {
VariableUsage *aliased = find(*aliases);
if (aliased) {
aliased->use();
aliased->_lastAccess = tok;
}
}
}
}
void Variables::modified(unsigned int varid, const Token* tok)
{
VariableUsage *usage = find(varid);
if (usage) {
usage->_modified = true;
usage->_lastAccess = tok;
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;
aliased->_lastAccess = tok;
}
}
}
}
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 const Token* doAssignment(Variables &variables, const Token *tok, bool dereference, const Scope *scope)
{
// a = a + b;
if (Token::Match(tok, "%var% = %var% !!;") && tok->varId() == tok->tokAt(2)->varId()) {
return tok->tokAt(2);
}
const Token* const tokOld = tok;
// check for aliased variable
const unsigned int varid1 = tok->varId();
Variables::VariableUsage *var1 = variables.find(varid1);
if (var1) {
// jump behind '='
tok = tok->next();
while (tok->str() != "=") {
if (tok->varId())
variables.read(tok->varId(), tok);
tok = tok->next();
}
tok = tok->next();
if (Token::Match(tok, "&| %var%") ||
Token::Match(tok, "( const| struct|union| %type% *| ) &| %var%") ||
Token::Match(tok, "( const| struct|union| %type% *| ) ( &| %var%") ||
Token::Match(tok->next(), "< const| struct|union| %type% *| > ( &| %var%")) {
bool addressOf = false;
if (Token::Match(tok, "%var% ."))
variables.use(tok->varId(), tok); // use = read + write
// check for C style cast
if (tok->str() == "(") {
tok = tok->next();
if (tok->str() == "const")
tok = tok->next();
if (Token::Match(tok, "struct|union"))
tok = tok->next();
tok = tok->next();
if (tok->str() == "*")
tok = tok->next();
tok = tok->next();
if (tok->str() == "&") {
addressOf = true;
tok = tok->next();
} else if (tok->str() == "(") {
tok = tok->next();
if (tok->str() == "&") {
addressOf = true;
tok = tok->next();
}
}
}
// check for C++ style cast
else if (tok->str().find("cast") != std::string::npos &&
tok->strAt(1) == "<") {
tok = tok->tokAt(2);
if (tok->str() == "const")
tok = tok->next();
if (Token::Match(tok, "struct|union"))
tok = tok->next();
tok = tok->next();
if (tok->str() == "*")
tok = tok->next();
tok = tok->tokAt(2);
if (tok->str() == "&") {
addressOf = true;
tok = tok->next();
}
}
// no cast, no ?
else if (!Token::Match(tok, "%var% ?")) {
if (tok->str() == "&") {
addressOf = true;
tok = tok->next();
} else if (tok->str() == "new")
return tokOld;
}
// check if variable is local
unsigned int varid2 = tok->varId();
Variables::VariableUsage* var2 = variables.find(varid2);
if (var2) { // local variable (alias or read it)
if (var1->_type == Variables::pointer || var1->_type == Variables::pointerArray) {
if (dereference)
variables.read(varid2, tok);
else {
if (addressOf ||
var2->_type == Variables::array ||
var2->_type == Variables::pointer) {
bool replace = true;
// pointerArray => don't replace
if (var1->_type == Variables::pointerArray)
replace = false;
// check if variable declared in same scope
else if (scope == var1->_var->scope())
replace = true;
// not in same scope as declaration
else {
// no other assignment in this scope
if (var1->_assignments.find(scope) == var1->_assignments.end() ||
scope->type == Scope::eSwitch) {
// 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, merge them otherwise
replace = (var1->_assignments.size() == 1);
}
}
variables.alias(varid1, varid2, replace);
} else if (tok->strAt(1) == "?") {
if (var2->_type == Variables::reference)
variables.readAliases(varid2, tok);
else
variables.read(varid2, tok);
} else {
variables.read(varid2, tok);
}
}
} else if (var1->_type == Variables::reference) {
variables.alias(varid1, varid2, true);
} else {
if (var2->_type == Variables::pointer && tok->strAt(1) == "[")
variables.readAliases(varid2, tok);
variables.read(varid2, tok);
}
} 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->_var->scope() == scope)
variables.clearAliases(varid1);
else {
// no other assignment in this scope
if (var1->_assignments.find(scope) == 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);
}
}
}
}
} else
tok = tokOld;
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 tok;
}
static bool isRecordTypeWithoutSideEffects(const Scope* type)
{
// a type that has no side effects (no constructors and no members with constructors)
/** @todo false negative: check constructors for side effects */
if (type && type->numConstructors == 0 &&
(type->varlist.empty() || type->needInitialization == Scope::True)) {
bool yes = true;
for (std::vector<Scope::BaseInfo>::const_iterator i = type->derivedFrom.begin(); yes && i != type->derivedFrom.end(); ++i)
yes = isRecordTypeWithoutSideEffects(i->scope);
return yes;
}
return false;
}
static bool isPartOfClassStructUnion(const Token* tok)
{
for (; tok; tok = tok->previous()) {
if (tok->str() == "}" || tok->str() == ")")
tok = tok->link();
else if (tok->str() == "(")
return(false);
else if (tok->str() == "{") {
return(tok->strAt(-1) == "struct" || tok->strAt(-2) == "struct" || tok->strAt(-1) == "class" || tok->strAt(-2) == "class" || tok->strAt(-1) == "union" || tok->strAt(-2) == "union");
}
}
return false;
}
// Skip [ .. ]
static const Token * skipBrackets(const Token *tok)
{
while (tok && tok->str() == "[")
tok = tok->link()->next();
return tok;
}
// Skip [ .. ] . x
static const Token * skipBracketsAndMembers(const Token *tok)
{
while (tok) {
if (tok->str() == "[")
tok = tok->link()->next();
else if (Token::Match(tok, ". %var%"))
tok = tok->tokAt(2);
else
break;
}
return tok;
}
//---------------------------------------------------------------------------
// Usage of function variables
//---------------------------------------------------------------------------
void CheckUnusedVar::checkFunctionVariableUsage_iterateScopes(const Scope* const scope, Variables& variables, bool insideLoop, std::vector<unsigned int> &usedVariables)
{
// Find declarations if the scope is executable..
if (scope->isExecutable()) {
// Find declarations
for (std::list<Variable>::const_iterator i = scope->varlist.begin(); i != scope->varlist.end(); ++i) {
if (i->isThrow() || i->isExtern())
continue;
Variables::VariableType type = Variables::none;
if (i->isArray() && (i->nameToken()->previous()->str() == "*" || i->nameToken()->strAt(-2) == "*"))
type = Variables::pointerArray;
else if (i->isArray() && i->nameToken()->previous()->str() == "&")
type = Variables::referenceArray;
else if (i->isArray())
type = Variables::array;
else if (i->isReference())
type = Variables::reference;
else if (i->nameToken()->previous()->str() == "*" && i->nameToken()->strAt(-2) == "*")
type = Variables::pointerPointer;
else if (i->isPointer())
type = Variables::pointer;
else if (_tokenizer->isC() || i->typeEndToken()->isStandardType() || isRecordTypeWithoutSideEffects(i->type()) || Token::simpleMatch(i->typeStartToken(), "std ::"))
type = Variables::standard;
if (type == Variables::none || isPartOfClassStructUnion(i->typeStartToken()))
continue;
const Token* defValTok = i->nameToken()->next();
for (; defValTok; defValTok = defValTok->next()) {
if (defValTok->str() == "[")
defValTok = defValTok->link();
else if (defValTok->str() == "(" || defValTok->str() == "=") {
variables.addVar(&*i, type, true);
break;
} else if (defValTok->str() == ";" || defValTok->str() == "," || defValTok->str() == ")") {
variables.addVar(&*i, type, i->isStatic());
break;
}
}
if (i->isArray() && i->isClass()) // Array of class/struct members. Initialized by ctor.
variables.write(i->varId(), i->nameToken());
if (i->isArray() && Token::Match(i->nameToken(), "%var% [ %var% ]")) // Array index variable read.
variables.read(i->nameToken()->tokAt(2)->varId(), i->nameToken());
if (defValTok && defValTok->str() == "=") {
if (defValTok->next() && defValTok->next()->str() == "{") {
for (const Token* tok = defValTok; tok && tok != defValTok->linkAt(1); tok = tok->next())
if (Token::Match(tok, "%var%")) // Variables used to initialize the array read.
variables.read(tok->varId(), i->nameToken());
} else
doAssignment(variables, i->nameToken(), false, scope);
} else if (Token::Match(defValTok, "( %var% )")) // Variables used to initialize the variable read.
variables.readAll(defValTok->next()->varId(), i->nameToken()); // ReadAll?
}
}
if (scope->classDef->str() == "for" || scope->classDef->str() == "while") {
insideLoop = true;
}
// Check variable usage
for (const Token *tok = scope->classDef->next(); tok && tok != scope->classEnd; tok = tok->next()) {
if (tok->str() == "for" || tok->str() == "while") {
for (std::list<Scope*>::const_iterator i = scope->nestedList.begin(); i != scope->nestedList.end(); ++i) {
if ((*i)->classDef == tok) { // Find associated scope
checkFunctionVariableUsage_iterateScopes(*i, variables, true, usedVariables); // Scan child scope
insideLoop = false;
std::vector<unsigned int>::iterator it;
for (it = usedVariables.begin(); it != usedVariables.end(); ++it) {
variables.read((*it), tok);
}
tok = (*i)->classStart->link();
break;
}
}
if (!tok)
break;
}
if (tok->str() == "{") {
for (std::list<Scope*>::const_iterator i = scope->nestedList.begin(); i != scope->nestedList.end(); ++i) {
if ((*i)->classStart == tok) { // Find associated scope
checkFunctionVariableUsage_iterateScopes(*i, variables, insideLoop, usedVariables); // Scan child scope
tok = tok->link();
break;
}
}
if (!tok)
break;
}
if (Token::Match(tok, "asm ( %str% )")) {
variables.clear();
break;
}
if (Token::Match(tok->previous(), "[;{}]")) {
for (const Token* tok2 = tok->next(); tok2; tok2 = tok2->next()) {
if (tok2->varId()) {
const Variable* var = _tokenizer->getSymbolDatabase()->getVariableFromVarId(tok2->varId());
if (var && var->nameToken() == tok2) { // Declaration: Skip
tok = tok2->next();
if (Token::Match(tok, "( %var% )")) // Simple initialization through copy ctor
tok = tok->next();
else if (Token::Match(tok, "= %var% ;")) // Simple initialization
tok = tok->next();
else if (var->typeEndToken()->str() == ">") // Be careful with types like std::vector
tok = tok->previous();
break;
}
} else if (Token::Match(tok2, "[;({=]"))
break;
}
}
// Freeing memory (not considered "using" the pointer if it was also allocated in this function)
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(3);
} else {
varid = tok->next()->varId();
tok = tok->next();
}
Variables::VariableUsage *var = variables.find(varid);
if (var && !var->_allocateMemory) {
variables.readAll(varid, tok);
}
}
else if (Token::Match(tok, "return|throw")) {
for (const Token *tok2 = tok->next(); tok2; tok2 = tok2->next()) {
if (tok2->varId())
variables.readAll(tok2->varId(), tok);
else if (tok2->str() == ";")
break;
}
}
else if (Token::Match(tok->tokAt(-2), "while|if") && tok->strAt(1) == "=" && tok->varId() && tok->varId() == tok->tokAt(2)->varId()) {
variables.use(tok->tokAt(2)->varId(), tok);
}
// 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 (tok->type() == Token::eIncDecOp) {
pre = true;
tok = tok->next();
}
if (tok->next()->type() == Token::eIncDecOp)
post = true;
const unsigned int varid1 = tok->varId();
const Token *start = tok;
tok = doAssignment(variables, tok, dereference, scope);
if (pre || post)
variables.use(varid1, tok);
if (dereference) {
Variables::VariableUsage *var = variables.find(varid1);
if (var && var->_type == Variables::array)
variables.write(varid1, tok);
variables.writeAliases(varid1, tok);
variables.read(varid1, tok);
} else {
Variables::VariableUsage *var = variables.find(varid1);
if (var && var->_type == Variables::reference) {
variables.writeAliases(varid1, tok);
variables.read(varid1, tok);
}
// 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|kmalloc|kzalloc|kcalloc|strdup|strndup|vmalloc|g_new0|g_try_new|g_new|g_malloc|g_malloc0|g_try_malloc|g_try_malloc0|g_strdup|g_strndup|g_strdup_printf")) {
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()) {
const Variable* variable = _tokenizer->getSymbolDatabase()->getVariableFromVarId(start->varId());
if (!variable || !isRecordTypeWithoutSideEffects(variable->type()))
allocate = false;
}
}
if (allocate)
variables.allocateMemory(varid1, tok);
else
variables.write(varid1, tok);
} else if (varid1 && Token::Match(tok, "%varid% .", varid1)) {
variables.use(varid1, tok);
} else {
variables.write(varid1, tok);
}
Variables::VariableUsage *var2 = variables.find(tok->varId());
if (var2) {
if (var2->_type == Variables::reference) {
variables.writeAliases(tok->varId(), tok);
variables.read(tok->varId(), tok);
} else if (tok->varId() != varid1 && Token::Match(tok, "%var% ."))
variables.read(tok->varId(), tok);
else if (tok->varId() != varid1 &&
var2->_type == Variables::standard &&
tok->strAt(-1) != "&")
variables.use(tok->varId(), tok);
}
}
const Token * const equal = skipBracketsAndMembers(tok->next());
// checked for chained assignments
if (tok != start && equal && 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(skipBracketsAndMembers(tok->next()), "=")) ||
(Token::simpleMatch(tok, "* (") && Token::simpleMatch(tok->next()->link(), ") ="))) {
if (tok->str() == "*") {
tok = tok->tokAt(2);
if (tok->str() == "(")
tok = tok->link()->next();
}
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(skipBrackets(tok->next()), "= new|malloc|calloc|kmalloc|kzalloc|kcalloc|strdup|strndup|vmalloc|g_new0|g_try_new|g_new|g_malloc|g_malloc0|g_try_malloc|g_try_malloc0|g_strdup|g_strndup|g_strdup_printf")) {
variables.allocateMemory(varid, tok);
} else if (var->_type == Variables::pointer || var->_type == Variables::reference) {
variables.read(varid, tok);
variables.writeAliases(varid, tok);
} else if (var->_type == Variables::pointerArray) {
tok = doAssignment(variables, tok, false, scope);
} else
variables.writeAll(varid, tok);
}
}
else if (Token::Match(tok, "& %var%")) {
if (tok->previous()->isName() || tok->previous()->isNumber()) { // bitop
variables.read(tok->next()->varId(), tok);
} else // addressof
variables.use(tok->next()->varId(), tok); // use = read + write
usedVariables.push_back(tok->next()->varId());
} else if (Token::Match(tok, ">> %var%")) {
variables.use(tok->next()->varId(), tok); // use = read + write
usedVariables.push_back(tok->next()->varId());
} else if (Token::Match(tok, "%var% >>|&") && Token::Match(tok->previous(), "[{};:]")) {
variables.read(tok->varId(), tok);
usedVariables.push_back(tok->next()->varId());
}
// function parameter
else if (Token::Match(tok, "[(,] %var% [")) {
variables.use(tok->next()->varId(), tok); // use = read + write
usedVariables.push_back(tok->next()->varId());
} else if (Token::Match(tok, "[(,] %var% [,)]") && tok->previous()->str() != "*") {
variables.use(tok->next()->varId(), tok); // use = read + write
usedVariables.push_back(tok->next()->varId());
} else if (Token::Match(tok, "[(,] (") &&
Token::Match(tok->next()->link(), ") %var% [,)]")) {
variables.use(tok->next()->link()->next()->varId(), tok); // use = read + write
usedVariables.push_back(tok->next()->link()->next()->varId());
}
// function
else if (Token::Match(tok, "%var% (")) {
variables.read(tok->varId(), tok);
usedVariables.push_back(tok->varId());
if (Token::Match(tok->tokAt(2), "%var% =")) {
variables.read(tok->tokAt(2)->varId(), tok);
usedVariables.push_back(tok->tokAt(2)->varId());
}
}
else if (Token::Match(tok, "[{,] %var% [,}]")) {
variables.read(tok->next()->varId(), tok);
usedVariables.push_back(tok->next()->varId());
}
else if (Token::Match(tok, "%var% .")) {
variables.use(tok->varId(), tok); // use = read + write
usedVariables.push_back(tok->varId());
}
else if (tok->isExtendedOp() &&
Token::Match(tok->next(), "%var%") && !Token::Match(tok->next(), "true|false|new") && tok->strAt(2) != "=") {
variables.readAll(tok->next()->varId(), tok);
usedVariables.push_back(tok->next()->varId());
}
else if (Token::Match(tok, "%var%") && tok->next() && (tok->next()->str() == ")" || tok->next()->isExtendedOp())) {
variables.readAll(tok->varId(), tok);
usedVariables.push_back(tok->varId());
}
else if (Token::Match(tok, "%var% ;") && Token::Match(tok->previous(), "[;{}:]")) {
variables.readAll(tok->varId(), tok);
usedVariables.push_back(tok->varId());
}
else if (Token::Match(tok, "++|-- %var%")) {
if (!Token::Match(tok->previous(), "[;{}:]"))
variables.use(tok->next()->varId(), tok);
else
variables.modified(tok->next()->varId(), tok);
usedVariables.push_back(tok->next()->varId());
}
else if (Token::Match(tok, "%var% ++|--")) {
if (!Token::Match(tok->previous(), "[;{}:]"))
variables.use(tok->varId(), tok);
else
variables.modified(tok->varId(), tok);
usedVariables.push_back(tok->varId());
}
else if (tok->isAssignmentOp()) {
for (const Token *tok2 = tok->next(); tok2 && tok2->str() != ";"; tok2 = tok2->next()) {
if (tok2->varId()) {
if (tok2->next()->isAssignmentOp())
variables.write(tok2->varId(), tok);
else
variables.read(tok2->varId(), tok);
usedVariables.push_back(tok2->varId());
}
}
}
}
}
void CheckUnusedVar::checkFunctionVariableUsage()
{
if (!_settings->isEnabled("style"))
return;
// Parse all executing scopes..
const SymbolDatabase *symbolDatabase = _tokenizer->getSymbolDatabase();
for (std::list<Scope>::const_iterator scope = symbolDatabase->scopeList.begin(); scope != symbolDatabase->scopeList.end(); ++scope) {
// only check functions
if (scope->type != Scope::eFunction)
continue;
// varId, usage {read, write, modified}
Variables variables;
std::vector<unsigned int> usedVariables;
checkFunctionVariableUsage_iterateScopes(&*scope, variables, false, usedVariables);
// Check usage of all variables in the current scope..
for (Variables::VariableMap::const_iterator it = variables.varUsage().begin(); it != variables.varUsage().end(); ++it) {
const Variables::VariableUsage &usage = it->second;
const std::string &varname = usage._var->name();
const Variable* var = symbolDatabase->getVariableFromVarId(it->first);
// variable has been marked as unused so ignore it
if (usage._var->nameToken()->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._lastAccess, varname);
// variable has not been written, read, or modified
else if (usage.unused() && !usage._modified)
unusedVariableError(usage._var->nameToken(), varname);
// variable has not been written but has been modified
else if (usage._modified && !usage._write && !usage._allocateMemory && !Token::simpleMatch(var->typeStartToken(), "std ::"))
unassignedVariableError(usage._var->nameToken(), varname);
// variable has been written but not read
else if (!usage._read && !usage._modified)
unreadVariableError(usage._lastAccess, varname);
// variable has been read but not written
else if (!usage._write && !usage._allocateMemory && !Token::simpleMatch(var->typeStartToken(), "std ::"))
unassignedVariableError(usage._var->nameToken(), 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 (tok->strAt(-1) == "extern")
continue;
if ((!tok->previous() || tok->previous()->str() == ";") && Token::Match(tok->linkAt(2), ("} ; " + 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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