Peter M. Groen / cxxopts

These were detected using -fsanitize=undefined parsing values equal to
INT_MAX and INT_MIN.

* Parse 1 as "true" and 0 as "false" for boolean options.

Fixes #171. Allows invalid syntax for short options to be ignored.

Fixes #175. This was broken when throwing an exception on missing
positional parameters in #169.

Fixes #169. It seems reasonable to throw an exception when an attempt is
made to parse into positional parameters that don't exist.

String literals with the prefix `u8` now have the type `const char8_t[N]` in
C++20. As a consequence the library does not compile in c++2a mode with GCC
(you can't concatenate `std::basic_string<char>` and `const char8_t[]` as
`char` and `char8_t` are different types).

Fixes #166.

The empty string caused the vector to have one element which caused
the test at line 2041 to always fail.

Fixes #157. Fix the wording in the README about booleans.

Windows is broken and defines `min` and `max` as a macro, adding parentheses stops them from being expanded.

g++ 8.2.0 refuses to compile the test suite because of polymorphic types
that are caught by value. They shall be caught by reference instead.

Fixes #124.

Fixes #132. Since the map of options is shared between Options and
ParseResult, they should use a shared pointer instead of a reference so
that ParseResult can be returned without referencing destroyed memory.

Fixes #143. There is no reason to make the tests optional.

Fixes #121. Removes the unused `ParseResult::get_option`.

Fixes #115. Read the version number out of `cxxopts.hpp` instead of
having to duplicate it in CMakeLists.txt.

Fixes #109. Although we always used numbers in the ASCII range, it was
in a `size_t`, leading to a warning about possible loss of data on some
compilers.

Fixes #101. Allows leading zeroes in the integer parser.

Allows unrecognised options to be left alone by the parser without throwing an exception.

This reverts commit 0f819a5cabb611ada4c41a5208c6bf1178f804be.

* Added const to argv type for better interoperability.

Fixes #102. Don't show the default value when it is a boolean and the
value is false. Note that this is a bit of a hack and the
implementation should probably be reevaluated in the future.

Fixes #93. This adds C++17 only support for `std::optional` values for
command line parameters.

Fixes #96. Default values of options not specified on the command line
had a `count` of 1. It would be better if they had a count of 0 because
they were not actually specified, so that count is only for options
given by the user.