Try to use the clipp library for argument parsing.

.gitmodules

@@ -10,3 +10,6 @@
 	path = include/lol/3rdparty/portable-file-dialogs
 	url = ../../samhocevar/portable-file-dialogs.git
 	branch = master
+[submodule "clipp"]
+	path = include/lol/3rdparty/clipp
+	url = ../../muellan/clipp.git

include/lol/3rdparty/clipp

@@ -0,0 +1 @@
+Subproject commit 2c32b2f1f7cc530b1ec1f62c92f698643bb368db

include/lol/getopt

@@ -13,6 +13,6 @@
 #pragma once
 
 #include "private/push_macros.h"
-#include "private/sys/getopt.h"
+#include "3rdparty/clipp/include/clipp.h"
 #include "private/pop_macros.h"
 

include/lol/private/sys/getopt.h

@@ -1,173 +0,0 @@
-//
-//  Lol Engine
-//
-//  Copyright © 2002—2016 Sam Hocevar <sam@hocevar.net>
-//
-//  Lol Engine is free software. It comes without any warranty, to
-//  the extent permitted by applicable law. You can redistribute it
-//  and/or modify it under the terms of the Do What the Fuck You Want
-//  to Public License, Version 2, as published by the WTFPL Task Force.
-//  See http://www.wtfpl.net/ for more details.
-//
-
-#pragma once
-
-//
-// The getopt functions
-// --------------------
-//
-
-#include <vector>
-#include <string>
-#include <cstring>
-
-namespace lol
-{
-
-class getopt
-{
-public:
-    getopt(int argc, char ** argv)
-      : m_argc(argc),
-        m_argv(argv)
-    {
-    }
-
-    getopt(int argc, char * const * argv)
-      : m_argc(argc),
-        m_argv(argv)
-    {
-    }
-
-    void add_opt(int short_opt, char const *long_opt, bool has_arg)
-    {
-        optdesc o { long_opt, has_arg, nullptr, short_opt };
-        m_opts.push_back(o);
-
-        /* “The standards require that the argument [to isalnum()] is either
-         * EOF or a value that is representable in the type unsigned char.” */
-        if ((int)(unsigned char)short_opt == short_opt && isalnum(short_opt))
-        {
-            m_optstring += (char)short_opt;
-            if (has_arg)
-                m_optstring += ':';
-        }
-    }
-
-    int parse()
-    {
-        /* XXX: this getopt_long implementation should not be trusted for other
-         * applications without any serious peer reviewing. It “just works” with
-         * zzuf and a few libcaca programs but may fail miserably in other
-         * programs. */
-        char **argv = (char **)(uintptr_t)m_argv;
-        char *flag;
-
-        if (this->index >= m_argc)
-            return -1;
-
-        flag = argv[this->index];
-
-        if (flag[0] == '-' && flag[1] != '-')
-        {
-            char const *tmp;
-            int ret = flag[1];
-
-            if (ret == '\0')
-                return -1;
-
-            tmp = strchr(m_optstring.c_str(), ret);
-            if (!tmp || ret == ':')
-                return '?';
-
-            ++this->index;
-            if (tmp[1] == ':')
-            {
-                if (flag[2] != '\0')
-                    this->arg = flag + 2;
-                else
-                {
-                    if (this->index >= m_argc)
-                        goto too_few;
-                    this->arg = argv[this->index++];
-                }
-                return ret;
-            }
-
-            if (flag[2] != '\0')
-            {
-                flag[1] = '-';
-                --this->index;
-                ++argv[this->index];
-            }
-
-            return ret;
-        }
-
-        if (flag[0] == '-' && flag[1] == '-')
-        {
-            if (flag[2] == '\0')
-                return -1;
-
-            for (int i = 0; m_opts[i].name; ++i)
-            {
-                size_t l = strlen(m_opts[i].name);
-
-                if (strncmp(flag + 2, m_opts[i].name, l))
-                    continue;
-
-                switch (flag[2 + l])
-                {
-                case '=':
-                    if (!m_opts[i].has_arg)
-                        goto bad_opt;
-                    ++this->index;
-                    this->arg = flag + 2 + l + 1;
-                    return m_opts[i].val;
-                case '\0':
-                    ++this->index;
-                    if (m_opts[i].has_arg)
-                    {
-                        if (this->index >= m_argc)
-                            goto too_few;
-                        this->arg = argv[this->index++];
-                    }
-                    return m_opts[i].val;
-                default:
-                    break;
-                }
-            }
-        bad_opt:
-            fprintf(stderr, "%s: unrecognized option `%s'\n", argv[0], flag);
-            return '?';
-
-        too_few:
-            fprintf(stderr, "%s: option `%s' requires an argument\n",
-                    argv[0], flag);
-            return '?';
-        }
-
-        return -1;
-    }
-
-    int index = 1;
-    char *arg = nullptr;
-
-private:
-    struct optdesc
-    {
-        char const *name;
-        int has_arg;
-        int *flag;
-        int val;
-    };
-
-    int m_argc;
-    char * const *m_argv;
-
-    std::string m_optstring;
-    std::vector<optdesc> m_opts;
-};
-
-} // namespace lol
-