cppcheck/checkother.cpp

/*
 * cppcheck - c/c++ syntax checking
 * Copyright (C) 2007-2009 Daniel Marjamäki, Reijo Tomperi, Nicolas Le Cam
 *
 * 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 "checkother.h"

#include <list>
#include <map>
#include <sstream>
#include <stdlib.h>     // <- atoi
#include <cstring>
#include <cctype>
//---------------------------------------------------------------------------




//---------------------------------------------------------------------------
// Warning on C-Style casts.. p = (kalle *)foo;
//---------------------------------------------------------------------------

CheckOther::CheckOther(const Tokenizer *tokenizer, ErrorLogger *errorLogger)
{
    _tokenizer = tokenizer;
    _errorLogger = errorLogger;
}

CheckOther::~CheckOther()
{

}

void CheckOther::WarningOldStylePointerCast()
{
    for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next())
    {
        // Old style pointer casting..
        if (!Token::Match(tok, "( %type% * ) %var%"))
            continue;

        // Is "type" a class?
        const std::string pattern("class " + tok->next()->str());
        if (!Token::findmatch(_tokenizer->tokens(), pattern.c_str()))
            continue;

        std::ostringstream ostr;
        ostr << _tokenizer->fileLine(tok) << ": C-style pointer casting";
        _errorLogger->reportErr(ostr.str());
    }
}




//---------------------------------------------------------------------------
// Redundant code..
//---------------------------------------------------------------------------

void CheckOther::WarningRedundantCode()
{

    // if (p) delete p
    for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next())
    {
        if (tok->str() != "if")
            continue;

        const char *varname1 = NULL;
        const Token *tok2 = NULL;

        if (Token::Match(tok, "if ( %var% )"))
        {
            varname1 = tok->strAt(2);
            tok2 = tok->tokAt(4);
        }
        else if (Token::Match(tok, "if ( %var% != NULL )"))
        {
            varname1 = tok->strAt(2);
            tok2 = tok->tokAt(6);
        }

        if (varname1 == NULL || tok2 == NULL)
            continue;

        bool err = false;
        if (tok2->str() == "{")
        {
            tok2 = tok2->next();

            if (Token::Match(tok2, "delete %var% ; }"))
            {
                err = (strcmp(tok2->strAt(1), varname1) == 0);
            }
            else if (Token::Match(tok2, "delete [ ] %var% ; }"))
            {
                err = (strcmp(tok2->strAt(1), varname1) == 0);
            }
            else if (Token::Match(tok2, "free ( %var% ) ; }"))
            {
                err = (strcmp(tok2->strAt(2), varname1) == 0);
            }
            else if (Token::Match(tok2, "kfree ( %var% ) ; }"))
            {
                err = (strcmp(tok2->strAt(2), varname1) == 0);
            }
        }
        else
        {
            if (Token::Match(tok2, "delete %var% ;"))
            {
                err = (strcmp(tok2->strAt(1), varname1) == 0);
            }
            else if (Token::Match(tok2, "delete [ ] %var% ;"))
            {
                err = (strcmp(tok2->strAt(1), varname1) == 0);
            }
            else if (Token::Match(tok2, "free ( %var% ) ;"))
            {
                err = (strcmp(tok2->strAt(2), varname1) == 0);
            }
            else if (Token::Match(tok2, "kfree ( %var% ) ;"))
            {
                err = (strcmp(tok2->strAt(2), varname1) == 0);
            }
        }

        if (err)
        {
            std::ostringstream ostr;
            ostr << _tokenizer->fileLine(tok) << ": Redundant condition. It is safe to deallocate a NULL pointer";
            _errorLogger->reportErr(ostr.str());
        }
    }



    // Redundant condition
    // if (haystack.find(needle) != haystack.end())
    //    haystack.remove(needle);
    redundantCondition2();
}
//---------------------------------------------------------------------------

void CheckOther::redundantCondition2()
{
    const char pattern[] = "if ( %var% . find ( %any% ) != %var% . end ( ) ) "
                           "{|{|"
                           "    %var% . remove ( %any% ) ; "
                           "}|}|";
    const Token *tok = Token::findmatch(_tokenizer->tokens(), pattern);
    while (tok)
    {
        bool b = Token::Match(tok->tokAt(15), "{");

        // Get tokens for the fields %var% and %any%
        const Token *var1 = tok->tokAt(2);
        const Token *any1 = tok->tokAt(6);
        const Token *var2 = tok->tokAt(9);
        const Token *var3 = tok->tokAt(b ? 16 : 15);
        const Token *any2 = tok->tokAt(b ? 20 : 19);

        // Check if all the "%var%" fields are the same and if all the "%any%" are the same..
        if (var1->str() == var2->str() &&
            var2->str() == var3->str() &&
            any1->str() == any2->str())
        {
            std::ostringstream errmsg;
            errmsg << _tokenizer->fileLine(tok)
            << ": Redundant condition found. The remove function in the STL will not do anything if element doesn't exist";
            _errorLogger->reportErr(errmsg.str());
        }

        tok = Token::findmatch(tok->next(), pattern);
    }
}
//---------------------------------------------------------------------------




//---------------------------------------------------------------------------
// if (condition) ....
//---------------------------------------------------------------------------

void CheckOther::WarningIf()
{
    // Search for 'if (condition);'
    for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next())
    {
        if (!Token::simpleMatch(tok, "if ("))
            continue;

        // Search for the end paranthesis for the condition..
        int parlevel = 0;
        for (const Token *tok2 = tok->next(); tok2; tok2 = tok2->next())
        {
            if (tok2->str() == "(")
                ++parlevel;
            else if (tok2->str() == ")")
            {
                --parlevel;
                if (parlevel <= 0)
                {
                    if (Token::Match(tok2, ") ; !!else"))
                    {
                        std::ostringstream ostr;
                        ostr << _tokenizer->fileLine(tok) << ": Found \"if (condition);\"";
                        _errorLogger->reportErr(ostr.str());
                    }
                    break;
                }
            }
        }
    }

    // Search for 'a=b; if (a==b)'
    for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next())
    {
        // Begin statement?
        if (! Token::Match(tok, "[;{}]"))
            continue;
        tok = tok->next();
        if (! tok)
            break;

        if (!Token::Match(tok, "%var% = %var% ; if ( %var%"))
            continue;

        if (strcmp(tok->strAt(9), ")") != 0)
            continue;

        // var1 = var2 ; if ( var3 cond var4 )
        const char *var1 = tok->strAt(0);
        const char *var2 = tok->strAt(2);
        const char *var3 = tok->strAt(6);
        const char *cond = tok->strAt(7);
        const char *var4 = tok->strAt(8);

        // Check that var3 is equal with either var1 or var2
        if (strcmp(var1, var3) && strcmp(var2, var3))
            continue;

        // Check that var4 is equal with either var1 or var2
        if (strcmp(var1, var4) && strcmp(var2, var4))
            continue;

        // Check that there is a condition..
        const char *p[6] = {"==", "<=", ">=", "!=", "<", ">"};
        bool iscond = false;
        for (int i = 0; i < 6; i++)
        {
            if (strcmp(cond, p[i]) == 0)
            {
                iscond = true;
                break;
            }
        }
        if (!iscond)
            break;

        // we found the error. Report.
        std::ostringstream ostr;
        ostr << _tokenizer->fileLine(tok->tokAt(4)) << ": The condition is always ";
        for (int i = 0; i < 6; i++)
        {
            if (strcmp(cond, p[i]) == 0)
                ostr << (i < 3 ? "True" : "False");
        }
        _errorLogger->reportErr(ostr.str());
    }
}
//---------------------------------------------------------------------------




//---------------------------------------------------------------------------
// strtol(str, 0, radix)  <- radix must be 0 or 2-36
//---------------------------------------------------------------------------

void CheckOther::InvalidFunctionUsage()
{
    for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next())
    {
        if ((tok->str() != "strtol") && (tok->str() != "strtoul"))
            continue;

        // Locate the third parameter of the function call..
        int parlevel = 0;
        int param = 1;
        for (const Token *tok2 = tok->next(); tok2; tok2 = tok2->next())
        {
            if (Token::Match(tok2, "("))
                ++parlevel;
            else if (Token::Match(tok2, ")"))
                --parlevel;
            else if (parlevel == 1 && Token::Match(tok2, ","))
            {
                ++param;
                if (param == 3)
                {
                    if (Token::Match(tok2, ", %num% )"))
                    {
                        int radix = atoi(tok2->strAt(1));
                        if (!(radix == 0 || (radix >= 2 && radix <= 36)))
                        {
                            std::ostringstream ostr;
                            ostr << _tokenizer->fileLine(tok2) << ": Invalid radix in call to strtol or strtoul. Must be 0 or 2-36";
                            _errorLogger->reportErr(ostr.str());
                        }
                    }
                    break;
                }
            }
        }
    }
}
//---------------------------------------------------------------------------


//---------------------------------------------------------------------------
// Assignment in condition
//---------------------------------------------------------------------------

void CheckOther::CheckIfAssignment()
{
    for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next())
    {
        if (Token::Match(tok, "if ( %var% = %num% )") ||
            Token::Match(tok, "if ( %var% = %str% )") ||
            Token::Match(tok, "if ( %var% = %var% )"))
        {
            std::ostringstream ostr;
            ostr << _tokenizer->fileLine(tok) << ": Possible bug. Should it be '==' instead of '='?";
            _errorLogger->reportErr(ostr.str());
        }
    }
}
//---------------------------------------------------------------------------


//---------------------------------------------------------------------------
// Check for unsigned divisions
//---------------------------------------------------------------------------

void CheckOther::CheckUnsignedDivision()
{
    // Check for "ivar / uvar" and "uvar / ivar"
    std::map<std::string, char> varsign;
    for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next())
    {
        if (Token::Match(tok, "[{};(,] %type% %var% [;=,)]"))
        {
            const char *type = tok->strAt(1);
            if (strcmp(type, "char") == 0 || strcmp(type, "short") == 0 || strcmp(type, "int") == 0)
                varsign[tok->strAt(2)] = 's';
        }

        else if (Token::Match(tok, "[{};(,] unsigned %type% %var% [;=,)]"))
            varsign[tok->strAt(3)] = 'u';

        else if (!Token::Match(tok, "[).]") && Token::Match(tok->next(), "%var% / %var%"))
        {
            const char *varname1 = tok->strAt(1);
            const char *varname2 = tok->strAt(3);
            char sign1 = varsign[varname1];
            char sign2 = varsign[varname2];

            if (sign1 && sign2 && sign1 != sign2)
            {
                // One of the operands are signed, the other is unsigned..
                std::ostringstream ostr;
                ostr << _tokenizer->fileLine(tok->next()) << ": Warning: Division with signed and unsigned operators";
                _errorLogger->reportErr(ostr.str());
            }
        }

        else if (!Token::Match(tok, "[).]") && Token::Match(tok->next(), "%var% / - %num%"))
        {
            const char *varname1 = tok->strAt(1);
            char sign1 = varsign[varname1];
            if (sign1 == 'u')
            {
                std::ostringstream ostr;
                ostr << _tokenizer->fileLine(tok->next()) << ": Unsigned division. The result will be wrong.";
                _errorLogger->reportErr(ostr.str());
            }
        }

        else if (Token::Match(tok, "[([=*/+-] - %num% / %var%"))
        {
            const char *varname2 = tok->strAt(4);
            char sign2 = varsign[varname2];
            if (sign2 == 'u')
            {
                std::ostringstream ostr;
                ostr << _tokenizer->fileLine(tok->next()) << ": Unsigned division. The result will be wrong.";
                _errorLogger->reportErr(ostr.str());
            }
        }
    }
}
//---------------------------------------------------------------------------



//---------------------------------------------------------------------------
// Check scope of variables..
//---------------------------------------------------------------------------


void CheckOther::CheckVariableScope()
{
    // Walk through all tokens..
    bool func = false;
    int indentlevel = 0;
    for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next())
    {
        // Skip class and struct declarations..
        if ((tok->str() == "class") || (tok->str() == "struct"))
        {
            for (const Token *tok2 = tok; tok2; tok2 = tok2->next())
            {
                if (tok2->str() == "{")
                {
                    int indentlevel2 = 0;
                    for (tok = tok2; tok; tok = tok->next())
                    {
                        if (tok->str() == "{")
                        {
                            ++indentlevel2;
                        }
                        if (tok->str() == "}")
                        {
                            --indentlevel2;
                            if (indentlevel2 <= 0)
                            {
                                tok = tok->next();
                                break;
                            }
                        }
                    }
                    break;
                }
                if (Token::Match(tok2, "[,);]"))
                {
                    break;
                }
            }
            if (! tok)
                break;
        }

        if (tok->str() == "{")
        {
            ++indentlevel;
        }
        if (tok->str() == "}")
        {
            --indentlevel;
            if (indentlevel == 0)
                func = false;
        }
        if (indentlevel == 0 && Token::Match(tok, ") {"))
        {
            func = true;
        }
        if (indentlevel > 0 && func && Token::Match(tok, "[{};]"))
        {
            // First token of statement..
            const Token *tok1 = tok->next();
            if (! tok1)
                continue;

            if ((tok1->str() == "return") ||
                (tok1->str() == "delete") ||
                (tok1->str() == "goto") ||
                (tok1->str() == "else"))
                continue;

            // Variable declaration?
            if (Token::Match(tok1, "%var% %var% ;") ||
                Token::Match(tok1, "%var% %var% ="))
            {
                CheckVariableScope_LookupVar(tok1, tok1->strAt(1));
            }
        }
    }

}
//---------------------------------------------------------------------------

void CheckOther::CheckVariableScope_LookupVar(const Token *tok1, const char varname[])
{
    const Token *tok = tok1;

    // Skip the variable declaration..
    while (tok && !Token::Match(tok, ";"))
        tok = tok->next();

    // Check if the variable is used in this indentlevel..
    bool used = false, used1 = false;
    int indentlevel = 0;
    int parlevel = 0;
    bool for_or_while = false;
    while (indentlevel >= 0 && tok)
    {
        if (tok->str() == "{")
        {
            ++indentlevel;
        }

        else if (tok->str() == "}")
        {
            --indentlevel;
            if (indentlevel == 0)
            {
                if (for_or_while && used)
                    return;
                used1 = used;
                used = false;
            }
        }

        else if (tok->str() == "(")
        {
            ++parlevel;
        }

        else if (tok->str() == ")")
        {
            --parlevel;
        }


        else if (tok->str() == varname)
        {
            if (indentlevel == 0 || used1)
                return;
            used = true;
        }

        else if (indentlevel == 0)
        {
            if ((tok->str() == "for") || (tok->str() == "while"))
                for_or_while = true;
            if (parlevel == 0 && (tok->str() == ";"))
                for_or_while = false;
        }

        tok = tok->next();
    }

    // Warning if "used" is true
    std::ostringstream errmsg;
    errmsg << _tokenizer->fileLine(tok1) << " The scope of the variable '" << varname << "' can be limited";
    _errorLogger->reportErr(errmsg.str());
}
//---------------------------------------------------------------------------


//---------------------------------------------------------------------------
// Check for constant function parameters
//---------------------------------------------------------------------------

void CheckOther::CheckConstantFunctionParameter()
{
    for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next())
    {
        if (Token::Match(tok, "[,(] const std :: %type% %var% [,)]"))
        {
            std::ostringstream errmsg;
            errmsg << _tokenizer->fileLine(tok) << " " << tok->strAt(5) << " is passed by value, it could be passed by reference/pointer instead";
            _errorLogger->reportErr(errmsg.str());
        }

        else if (Token::Match(tok, "[,(] const %type% %var% [,)]"))
        {
            // Check if type is a struct or class.
            const std::string pattern(std::string("class|struct ") + tok->strAt(2));
            if (Token::findmatch(_tokenizer->tokens(), pattern.c_str()))
            {
                std::ostringstream errmsg;
                errmsg << _tokenizer->fileLine(tok) << " " << tok->strAt(3) << " is passed by value, it could be passed by reference/pointer instead";
                _errorLogger->reportErr(errmsg.str());
            }
        }
    }
}
//---------------------------------------------------------------------------


//---------------------------------------------------------------------------
// Check that all struct members are used
//---------------------------------------------------------------------------

void CheckOther::CheckStructMemberUsage()
{
    const char *structname = 0;

    for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next())
    {
        if (tok->fileIndex() != 0)
            continue;
        if (tok->str() == "}")
            structname = 0;
        if (Token::Match(tok, "struct|union %type% {"))
            structname = tok->strAt(1);

        if (structname && Token::Match(tok, "[{;]"))
        {
            const char *varname = 0;
            if (Token::Match(tok->next(), "%type% %var% [;[]"))
                varname = tok->strAt(2);
            else if (Token::Match(tok->next(), "%type% %type% %var% [;[]"))
                varname = tok->strAt(2);
            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;

            const std::string usagePattern(". " + std::string(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)
            {
                std::ostringstream errmsg;
                errmsg << _tokenizer->fileLine(tok->next()) << ": struct or union member '" << structname << "::" << varname << "' is never used";
                _errorLogger->reportErr(errmsg.str());
            }
        }
    }
}





//---------------------------------------------------------------------------
// Check usage of char variables..
//---------------------------------------------------------------------------

void CheckOther::CheckCharVariable()
{
    for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next())
    {
        // Declaring the variable..
        if (Token::Match(tok, "[{};(,] char %var% [;=,)]"))
        {
            // Set tok to point to the variable name
            tok = tok->tokAt(2);

            // Check usage of char variable..
            int indentlevel = 0;
            for (const Token *tok2 = tok->next(); tok2; tok2 = tok2->next())
            {
                if (tok2->str() == "{")
                    ++indentlevel;

                else if (tok2->str() == "}")
                {
                    --indentlevel;
                    if (indentlevel <= 0)
                        break;
                }

                std::string temp = "%var% [ " + tok->str() + " ]";
                if ((tok2->str() != ".") && Token::Match(tok2->next(), temp.c_str()))
                {
                    std::ostringstream errmsg;
                    errmsg << _tokenizer->fileLine(tok2->next()) << ": Warning - using char variable as array index";
                    _errorLogger->reportErr(errmsg.str());
                    break;
                }

                std::string tempFirst = "%var% [&|] " + tok->str();
                std::string tempSecond = tok->str() + " [&|]";
                if (Token::Match(tok2, tempFirst.c_str()) || Token::Match(tok2, tempSecond.c_str()))
                {
                    std::ostringstream errmsg;
                    errmsg << _tokenizer->fileLine(tok2) << ": Warning - using char variable in bit operation";
                    _errorLogger->reportErr(errmsg.str());
                    break;
                }
            }
        }
    }
}
//---------------------------------------------------------------------------






//---------------------------------------------------------------------------
// Incomplete statement..
//---------------------------------------------------------------------------

void CheckOther::CheckIncompleteStatement()
{
    int parlevel = 0;

    for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next())
    {
        if (tok->str() == "(")
            ++parlevel;
        else if (tok->str() == ")")
            --parlevel;

        if (parlevel != 0)
            continue;

        if ((tok->str() != "#") && Token::Match(tok->next(), "; %str%") && !Token::Match(tok->tokAt(3), ","))
        {
            std::ostringstream errmsg;
            errmsg << _tokenizer->fileLine(tok->next()) << ": Redundant code: Found a statement that begins with string constant";
            _errorLogger->reportErr(errmsg.str());
        }

        if (!Token::Match(tok, "#") && Token::Match(tok->next(), "; %num%") && !Token::Match(tok->tokAt(3), ","))
        {
            std::ostringstream errmsg;
            errmsg << _tokenizer->fileLine(tok->next()) << ": Redundant code: Found a statement that begins with numeric constant";
            _errorLogger->reportErr(errmsg.str());
        }
    }
}
//---------------------------------------------------------------------------






//---------------------------------------------------------------------------
// Unreachable code below a 'return'
//---------------------------------------------------------------------------

void CheckOther::unreachableCode()
{
    const Token *tok = Token::findmatch(_tokenizer->tokens(), "[;{}] return");
    while (tok)
    {
        // Goto the 'return' token
        tok = tok->next();

        // Locate the end of the 'return' statement
        while (tok && ! Token::Match(tok, ";"))
            tok = tok->next();
        while (tok && Token::Match(tok->next(), ";"))
            tok = tok->next();

        // If there is a statement below the return it is unreachable
        if (!Token::Match(tok, "; case|default|}|#") && !Token::Match(tok, "; %var% :"))
        {
            std::ostringstream errmsg;
            errmsg << _tokenizer->fileLine(tok->next()) << ": Unreachable code below a 'return'";
            _errorLogger->reportErr(errmsg.str());
        }

        // Find the next 'return' statement
        tok = Token::findmatch(tok, "[;{}] return");
    }
}
//---------------------------------------------------------------------------






//---------------------------------------------------------------------------
// Usage of function variables
//---------------------------------------------------------------------------

static bool isOp(const Token *tok)
{
    return bool(tok &&
                (tok->str() == "&&" ||
                 tok->str() == "||" ||
                 tok->str() == "==" ||
                 tok->str() == "!=" ||
                 tok->str() == "<" ||
                 tok->str() == "<=" ||
                 tok->str() == ">" ||
                 tok->str() == ">=" ||
                 tok->str() == "<<" ||
                 Token::Match(tok, "[+-*/%&!~|^,[])?:]")));
}

void CheckOther::functionVariableUsage()
{
    // Parse all executing scopes..
    const Token *tok1 = _tokenizer->tokens();
    if (!tok1)
        return;

    while ((tok1 = Token::findmatch(tok1->next(), ") const| {")) != NULL)
    {
        // Varname, usage {1=declare, 2=read, 4=write}
        std::map<std::string, unsigned int> varUsage;
        static const unsigned int USAGE_DECLARE = 1;
        static const unsigned int USAGE_READ    = 2;
        static const unsigned int USAGE_WRITE   = 4;

        int indentlevel = 0;
        for (const Token *tok = tok1; tok; tok = tok->next())
        {
            if (tok->str() == "{")
                ++indentlevel;
            else if (tok->str() == "}")
            {
                --indentlevel;
                if (indentlevel <= 0)
                    break;
            }
            else if (Token::Match(tok, "struct|union|class {") ||
                     Token::Match(tok, "struct|union|class %type% {"))
            {
                while (tok && tok->str() != "}")
                    tok = tok->next();
                if (tok)
                    continue;
                break;
            }

            if (Token::Match(tok, "[;{}] bool|char|short|int|long|float|double %var% ;|="))
                varUsage[ tok->strAt(2)] = USAGE_DECLARE;

            if (Token::Match(tok, "[;{}] bool|char|short|int|long|float|double * %var% ;|="))
                varUsage[ tok->strAt(3)] = USAGE_DECLARE;

            if (Token::Match(tok, "delete|return %var%"))
                varUsage[ tok->strAt(1)] |= USAGE_READ;

            if (Token::Match(tok, "%var% ="))
                varUsage[ tok->str()] |= USAGE_WRITE;

            if (Token::Match(tok, "else %var% ="))
                varUsage[ tok->strAt(1)] |= USAGE_WRITE;

            if (Token::Match(tok, ">>|& %var%"))
                varUsage[ tok->strAt(1)] |= USAGE_WRITE;

            if ((Token::Match(tok, "[(=&!]") || isOp(tok)) && Token::Match(tok->next(), "%var%"))
                varUsage[ tok->strAt(1)] |= USAGE_READ;

            if (Token::Match(tok, "-=|+=|*=|/=|&=|^= %var%") || Token::Match(tok, "|= %var%"))
                varUsage[ tok->strAt(1)] |= USAGE_READ;

            if (Token::Match(tok, "%var%") && (tok->next()->str() == ")" || isOp(tok->next())))
                varUsage[ tok->str()] |= USAGE_READ;

            if (Token::Match(tok, "[(,] %var% [,)]"))
                varUsage[ tok->strAt(1)] |= USAGE_WRITE;
        }

        // Check usage of all variables in the current scope..
        for (std::map<std::string, unsigned int>::const_iterator it = varUsage.begin(); it != varUsage.end(); ++it)
        {
            std::string varname = it->first;
            unsigned int usage = it->second;

            if (!std::isalpha(varname[0]))
                continue;

            if (!(usage & USAGE_DECLARE))
                continue;

            if (usage == USAGE_DECLARE)
            {
                std::ostringstream errmsg;
                errmsg << _tokenizer->fileLine(tok1->next()) << ": Unused variable '" << varname << "'";
                _errorLogger->reportErr(errmsg.str());
            }

            else if (!(usage & USAGE_READ))
            {
                std::ostringstream errmsg;
                errmsg << _tokenizer->fileLine(tok1->next()) << ": Variable '" << varname << "' is assigned a value that is never used";
                _errorLogger->reportErr(errmsg.str());
            }

            else if (!(usage & USAGE_WRITE))
            {
                std::ostringstream errmsg;
                errmsg << _tokenizer->fileLine(tok1->next()) << ": Variable '" << varname << "' is not assigned a value";
                _errorLogger->reportErr(errmsg.str());
            }
        }
    }
}