[Tclap-discuss] Sign conversion errors

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Hello!

I am using tclap in an image compression project, where sign conversion can
lead to subtle bugs, so I turn on "-Wall -Wconversion".  I also build with
clang, which seems to catch more warnings than gcc.

I see a number of conversion warnings in tclap, for example:

//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/home/aaron/src/grok/src/include/tclap/Arg.h:563:18: warning: implicit
conversion changes signedness: 'int' to 'std::__cxx11::basic_string<char,
std::char_traits<char>, std::allocator<char> >::size_type' (aka 'unsigned
long') [-Wsign-conversion]
        if (flag[i] == Arg::delimiter()) {
            ~~~~ ^
/home/aaron/src/grok/src/include/tclap/Arg.h:569:34: warning: implicit
conversion changes signedness: 'int' to 'std::__cxx11::basic_string<char,
std::char_traits<char>, std::allocator<char> >::size_type' (aka 'unsigned
long') [-Wsign-conversion]
        value = flag.substr(stop + 1);
                     ~~~~~~ ~~~~~^~~
/home/aaron/src/grok/src/include/tclap/Arg.h:570:31: warning: implicit
conversion changes signedness: 'int' to 'std::__cxx11::basic_string<char,
std::char_traits<char>, std::allocator<char> >::size_type' (aka 'unsigned
long') [-Wsign-conversion]
        flag = flag.substr(0, stop);
                    ~~~~~~    ^~~~
/home/aaron/src/grok/src/include/tclap/Arg.h:579:15: warning: implicit
conversion changes signedness: 'int' to 'std::__cxx11::basic_string<char,
std::char_traits<char>, std::allocator<char> >::size_type' (aka 'unsigned
long') [-Wsign-conversion]
        if (s[i] == Arg::blankChar()) return true;
            ~ ^
In file included from /home/aaron/src/grok/src/bin/jp2/grk_compress.cpp:102:
In file included from /home/aaron/src/grok/src/include/tclap/CmdLine.h:28:
/home/aaron/src/grok/src/include/tclap/SwitchArg.h:204:25: warning:
implicit conversion changes signedness: 'int' to 'std::vector::size_type'
(aka 'unsigned long') [-Wsign-conversion]
    if (argMatches(args[*i])) {
                   ~~~~ ^~
/home/aaron/src/grok/src/include/tclap/SwitchArg.h:206:23: warning:
implicit conversion changes signedness: 'int' to 'std::vector::size_type'
(aka 'unsigned long') [-Wsign-conversion]
        _setBy = args[*i];
                 ~~~~ ^~
/home/aaron/src/grok/src/include/tclap/SwitchArg.h:210:43: warning:
implicit conversion changes signedness: 'int' to 'std::vector::size_type'
(aka 'unsigned long') [-Wsign-conversion]
    } else if (combinedSwitchesMatch(args[*i])) {
                                     ~~~~ ^~
/home/aaron/src/grok/src/include/tclap/SwitchArg.h:214:40: warning:
implicit conversion changes signedness: 'int' to 'std::vector::size_type'
(aka 'unsigned long') [-Wsign-conversion]
        if (combinedSwitchesMatch(args[*i]))
                                  ~~~~ ^~
/home/aaron/src/grok/src/include/tclap/SwitchArg.h:222:34: warning:
implicit conversion changes signedness: 'int' to 'std::vector::size_type'
(aka 'unsigned long') [-Wsign-conversion]
        return lastCombined(args[*i]);
                            ~~~~ ^~
In file included from /home/aaron/src/grok/src/bin/jp2/grk_compress.cpp:102:
In file included from /home/aaron/src/grok/src/include/tclap/CmdLine.h:29:
/home/aaron/src/grok/src/include/tclap/MultiSwitchArg.h:132:25: warning:
implicit conversion changes signedness: 'int' to 'std::vector::size_type'
(aka 'unsigned long') [-Wsign-conversion]
    if (argMatches(args[*i])) {
                   ~~~~ ^~
/home/aaron/src/grok/src/include/tclap/MultiSwitchArg.h:135:23: warning:
implicit conversion changes signedness: 'int' to 'std::vector::size_type'
(aka 'unsigned long') [-Wsign-conversion]
        _setBy = args[*i];
                 ~~~~ ^~
/home/aaron/src/grok/src/include/tclap/MultiSwitchArg.h:143:43: warning:
implicit conversion changes signedness: 'int' to 'std::vector::size_type'
(aka 'unsigned long') [-Wsign-conversion]
    } else if (combinedSwitchesMatch(args[*i])) {
                                     ~~~~ ^~
/home/aaron/src/grok/src/include/tclap/MultiSwitchArg.h:151:43: warning:
implicit conversion changes signedness: 'int' to 'std::vector::size_type'
(aka 'unsigned long') [-Wsign-conversion]
        while (combinedSwitchesMatch(args[*i])) ++_value;
                                     ~~~~ ^~
In file included from /home/aaron/src/grok/src/bin/jp2/grk_compress.cpp:102:
In file included from /home/aaron/src/grok/src/include/tclap/CmdLine.h:30:
In file included from
/home/aaron/src/grok/src/include/tclap/UnlabeledValueArg.h:28:
/home/aaron/src/grok/src/include/tclap/ValueArg.h:291:29: warning: implicit
conversion changes signedness: 'int' to 'std::vector::size_type' (aka
'unsigned long') [-Wsign-conversion]
    std::string flag = args[*i];
                       ~~~~ ^~
In file included from /home/aaron/src/grok/src/bin/jp2/grk_compress.cpp:102:
In file included from /home/aaron/src/grok/src/include/tclap/CmdLine.h:31:
In file included from
/home/aaron/src/grok/src/include/tclap/UnlabeledMultiArg.h:27:
/home/aaron/src/grok/src/include/tclap/MultiArg.h:271:29: warning: implicit
conversion changes signedness: 'int' to 'std::vector::size_type' (aka
'unsigned long') [-Wsign-conversion]
    std::string flag = args[*i];
                       ~~~~ ^~
In file included from /home/aaron/src/grok/src/bin/jp2/grk_compress.cpp:102:
In file included from /home/aaron/src/grok/src/include/tclap/CmdLine.h:38:
/home/aaron/src/grok/src/include/tclap/StdOutput.h:441:30: warning:
implicit conversion changes signedness: 'int' to
'std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> >::size_type' (aka 'unsigned long') [-Wsign-conversion]
    std::string indentString(indentSpaces, ' ');
                ~~~~~~~~~~~~ ^~~~~~~~~~~~
/home/aaron/src/grok/src/include/tclap/StdOutput.h:448:44: warning:
implicit conversion changes signedness: 'int' to
'std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> >::size_type' (aka 'unsigned long') [-Wsign-conversion]
            os << indentString << s.substr(from) << std::endl;
                                    ~~~~~~ ^~~~
/home/aaron/src/grok/src/include/tclap/StdOutput.h:459:53: warning:
implicit conversion changes signedness: 'int' to
'std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> >::size_type' (aka 'unsigned long') [-Wsign-conversion]
            tooFar = s.find_first_of(splitChars, to + 1);
                       ~~~~~~~~~~~~~             ~~~^~~
/home/aaron/src/grok/src/include/tclap/StdOutput.h:468:15: warning:
implicit conversion changes signedness: 'int' to
'std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> >::size_type' (aka 'unsigned long') [-Wsign-conversion]
        if (s[to] != ' ') {
            ~ ^~
/home/aaron/src/grok/src/include/tclap/StdOutput.h:473:40: warning:
implicit conversion changes signedness: 'int' to
'std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> >::size_type' (aka 'unsigned long') [-Wsign-conversion]
        os << indentString << s.substr(from, to - from) << '\n';
                                ~~~~~~ ^~~~
/home/aaron/src/grok/src/include/tclap/StdOutput.h:473:49: warning:
implicit conversion changes signedness: 'int' to
'std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> >::size_type' (aka 'unsigned long') [-Wsign-conversion]
        os << indentString << s.substr(from, to - from) << '\n';
                                ~~~~~~       ~~~^~~~~~
/home/aaron/src/grok/src/include/tclap/StdOutput.h:476:18: warning:
implicit conversion changes signedness: 'int' to
'std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> >::size_type' (aka 'unsigned long') [-Wsign-conversion]
        for (; s[to] == ' '; to++) {}
               ~ ^~
/home/aaron/src/grok/src/include/tclap/StdOutput.h:481:53: warning:
implicit conversion changes signedness: 'int' to
'std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> >::size_type' (aka 'unsigned long') [-Wsign-conversion]
            indentString.insert(indentString.end(), secondLineOffset, ' ');
                         ~~~~~~                     ^~~~~~~~~~~~~~~~
/home/aaron/src/grok/src/include/tclap/StdOutput.h:444:17: warning:
implicit conversion loses integer precision:
'std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> >::size_type' (aka 'unsigned long') to 'int'
[-Wshorten-64-to-32]
    int end = s.length();
        ~~~   ~~^~~~~~~~
/home/aaron/src/grok/src/include/tclap/StdOutput.h:459:24: warning:
implicit conversion loses integer precision:
'std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> >::size_type' (aka 'unsigned long') to 'int'
[-Wshorten-64-to-32]
            tooFar = s.find_first_of(splitChars, to + 1);
                   ~ ~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /home/aaron/src/grok/src/bin/jp2/grk_compress.cpp:102:
/home/aaron/src/grok/src/include/tclap/CmdLine.h:488:49: warning: implicit
conversion changes signedness: 'int' to 'std::vector::size_type' (aka
'unsigned long') [-Wsign-conversion]
            if (!matched && _emptyCombined(args[i])) matched = true;
                                           ~~~~ ^
/home/aaron/src/grok/src/include/tclap/CmdLine.h:494:26: warning: implicit
conversion changes signedness: 'int' to 'std::vector::size_type' (aka
'unsigned long') [-Wsign-conversion]
                    args[i]));
                    ~~~~ ^
/home/aaron/src/grok/src/include/tclap/CmdLine.h:543:15: warning: implicit
conversion changes signedness: 'int' to 'std::__cxx11::basic_string<char,
std::char_traits<char>, std::allocator<char> >::size_type' (aka 'unsigned
long') [-Wsign-conversion]
        if (s[i] != Arg::blankChar()) return false;
            ~ ^
In file included from /home/aaron/src/grok/src/bin/jp2/grk_compress.cpp:102:
In file included from /home/aaron/src/grok/src/include/tclap/CmdLine.h:30:
In file included from
/home/aaron/src/grok/src/include/tclap/UnlabeledValueArg.h:28:
/home/aaron/src/grok/src/include/tclap/ValueArg.h:289:25: warning: implicit
conversion changes signedness: 'int' to 'std::vector::size_type' (aka
'unsigned long') [-Wsign-conversion]
    if (_hasBlanks(args[*i])) return false;
                   ~~~~ ^~
/home/aaron/src/grok/src/bin/jp2/grk_compress.cpp:579:22: note: in
instantiation of member function 'TCLAP::ValueArg<unsigned
int>::processArg' requested here
                ValueArg<uint32_t> kernelBuildOptionsArg("k", "KernelBuild",
                                   ^
In file included from /home/aaron/src/grok/src/bin/jp2/grk_compress.cpp:102:
In file included from /home/aaron/src/grok/src/include/tclap/CmdLine.h:30:
In file included from
/home/aaron/src/grok/src/include/tclap/UnlabeledValueArg.h:28:
/home/aaron/src/grok/src/include/tclap/ValueArg.h:291:29: warning: implicit
conversion changes signedness: 'int' to 'std::vector::size_type' (aka
'unsigned long') [-Wsign-conversion]
    std::string flag = args[*i];
                       ~~~~ ^~
/home/aaron/src/grok/src/include/tclap/ValueArg.h:308:36: warning: implicit
conversion changes signedness: 'int' to 'std::vector::size_type' (aka
'unsigned long') [-Wsign-conversion]
                _extractValue(args[*i]);
                              ~~~~ ^~
/home/aaron/src/grok/src/include/tclap/ValueArg.h:289:25: warning: implicit
conversion changes signedness: 'int' to 'std::vector::size_type' (aka
'unsigned long') [-Wsign-conversion]
    if (_hasBlanks(args[*i])) return false;
                   ~~~~ ^~
/home/aaron/src/grok/src/bin/jp2/grk_compress.cpp:586:22: note: in
instantiation of member function 'TCLAP::ValueArg<unsigned
short>::processArg' requested here
                ValueArg<uint16_t> rsizArg("Z", "RSIZ", "RSIZ", false, 0U,
                                   ^
In file included from /home/aaron/src/grok/src/bin/jp2/grk_compress.cpp:102:
In file included from /home/aaron/src/grok/src/include/tclap/CmdLine.h:30:
In file included from
/home/aaron/src/grok/src/include/tclap/UnlabeledValueArg.h:28:
/home/aaron/src/grok/src/include/tclap/ValueArg.h:291:29: warning: implicit
conversion changes signedness: 'int' to 'std::vector::size_type' (aka
'unsigned long') [-Wsign-conversion]
    std::string flag = args[*i];
                       ~~~~ ^~
/home/aaron/src/grok/src/include/tclap/ValueArg.h:308:36: warning: implicit
conversion changes signedness: 'int' to 'std::vector::size_type' (aka
'unsigned long') [-Wsign-conversion]
                _extractValue(args[*i]);
                              ~~~~ ^~
/home/aaron/src/grok/src/include/tclap/ValueArg.h:289:25: warning: implicit
conversion changes signedness: 'int' to 'std::vector::size_type' (aka
'unsigned long') [-Wsign-conversion]
    if (_hasBlanks(args[*i])) return false;
                   ~~~~ ^~
/home/aaron/src/grok/src/bin/jp2/grk_compress.cpp:595:20: note: in
instantiation of member function
'TCLAP::ValueArg<std::__cxx11::basic_string<char> >::processArg' requested
here
                ValueArg<string> IMFArg("z", "IMF", "IMF profile", false,
"", "string",
                                 ^
In file included from /home/aaron/src/grok/src/bin/jp2/grk_compress.cpp:102:
In file included from /home/aaron/src/grok/src/include/tclap/CmdLine.h:30:
In file included from
/home/aaron/src/grok/src/include/tclap/UnlabeledValueArg.h:28:
/home/aaron/src/grok/src/include/tclap/ValueArg.h:291:29: warning: implicit
conversion changes signedness: 'int' to 'std::vector::size_type' (aka
'unsigned long') [-Wsign-conversion]
    std::string flag = args[*i];
                       ~~~~ ^~
/home/aaron/src/grok/src/include/tclap/ValueArg.h:308:36: warning: implicit
conversion changes signedness: 'int' to 'std::vector::size_type' (aka
'unsigned long') [-Wsign-conversion]
                _extractValue(args[*i]);
                              ~~~~ ^~
/home/aaron/src/grok/src/include/tclap/ValueArg.h:289:25: warning: implicit
conversion changes signedness: 'int' to 'std::vector::size_type' (aka
'unsigned long') [-Wsign-conversion]
    if (_hasBlanks(args[*i])) return false;
                   ~~~~ ^~
/home/aaron/src/grok/src/bin/jp2/grk_compress.cpp:609:21: note: in
instantiation of member function 'TCLAP::ValueArg<int>::processArg'
requested here
                ValueArg<int32_t> deviceIdArg("G", "DeviceId", "Device ID",
false, 0U,
                                  ^
In file included from /home/aaron/src/grok/src/bin/jp2/grk_compress.cpp:102:
In file included from /home/aaron/src/grok/src/include/tclap/CmdLine.h:30:
In file included from
/home/aaron/src/grok/src/include/tclap/UnlabeledValueArg.h:28:
/home/aaron/src/grok/src/include/tclap/ValueArg.h:291:29: warning: implicit
conversion changes signedness: 'int' to 'std::vector::size_type' (aka
'unsigned long') [-Wsign-conversion]
    std::string flag = args[*i];
                       ~~~~ ^~
/home/aaron/src/grok/src/include/tclap/ValueArg.h:308:36: warning: implicit
conversion changes signedness: 'int' to 'std::vector::size_type' (aka
'unsigned long') [-Wsign-conversion]
                _extractValue(args[*i]);
                              ~~~~ ^~
/home/aaron/src/grok/src/include/tclap/ValueArg.h:289:25: warning: implicit
conversion changes signedness: 'int' to 'std::vector::size_type' (aka
'unsigned long') [-Wsign-conversion]
    if (_hasBlanks(args[*i])) return false;
                   ~~~~ ^~
/home/aaron/src/grok/src/bin/jp2/grk_compress.cpp:627:21: note: in
instantiation of member function 'TCLAP::ValueArg<unsigned
char>::processArg' requested here
                ValueArg<uint8_t> tpArg("u", "TP", "Tile part generation",
false, 0U,
                                  ^
In file included from /home/aaron/src/grok/src/bin/jp2/grk_compress.cpp:102:
In file included from /home/aaron/src/grok/src/include/tclap/CmdLine.h:30:
In file included from
/home/aaron/src/grok/src/include/tclap/UnlabeledValueArg.h:28:
/home/aaron/src/grok/src/include/tclap/ValueArg.h:291:29: warning: implicit
conversion changes signedness: 'int' to 'std::vector::size_type' (aka
'unsigned long') [-Wsign-conversion]
    std::string flag = args[*i];
                       ~~~~ ^~
/home/aaron/src/grok/src/include/tclap/ValueArg.h:308:36: warning: implicit
conversion changes signedness: 'int' to 'std::vector::size_type' (aka
'unsigned long') [-Wsign-conversion]
                _extractValue(args[*i]);

//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

I think this could solved by using size_t instead of int in a number of
places.

Interested to know your thoughts,
Aaron