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#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#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#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#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.
* `|` should be inside of `(…)`
It's possible to use `(t|true|T|True)` as `truthy_pattern` but still failing `true` as a truthy under my environment :-(
```
Apple LLVM version 8.0.0 (clang-800.0.42.1)
Target: x86_64-apple-darwin15.6.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
```
Fixes#83.
Adds an overload for positional arguments taking a
`std::initializer_list`. When using an `initializer_list` with one
argument, the function call is ambiguous matching both `std::string`
and `std::vector<std::string>`.
Fixes#84. Implicit values are not handled very well. For example:
--foo false true
--foo --bar
In the first, `false` is an argument to `--foo`, and then `true` is a
positional argument. In the second, because of the hyphen in `--bar`, `--foo`
is parsed with its implicit value. This seems inconsistent and unintuitive.
Better is that implicit values *never* consume the next parameter to be
completely consistent. This means that values with an implicit parameter
*must* be specified using the `--option=value` form.
