In the `Clap` derive macro, a function parameter named `arg_matches` is
generated using `quote!` - as a result, this parameter ends up with
call-site hygiene. However, `arg_matches` is written literally within
several `quote_spanned!` blocks, which generate an `arg_matches` token
with the hygiene of whatever span was passed to `quote_spanned!`.
If these two hygienes are different (for example, if the user invokes
the derive macro from a `macro_rules!` macro), then a usage of
`arg_matches` may not resolve to the `arg_matches` parameter definition.
This commit changes the generation of `arg_matches` identifiers to
always use `quote!`, ensuring that they will always be considered the
'same' identifier by Rust.
Updates the derive example handling environment variables to illustrate
the case where it contains a sensitive value which should not be
displayed on the help screen.
Closes https://github.com/clap-rs/clap/issues/2101
Due to macro expansions, a `syn` type may be wrapped in multiple
'layers' of `syn::Type::Group`. However, `clap_derive` currently does
not check for `syn::Type::Group`, which will cause an `Option` (along
with other matched types) to fail to be detected when it results from a
macro expansion.
This commit 'unwraps' outer type groups before checking the
user-provided types against well-known types. Currently, these groups
may not be present due to a rustc bug (rust-lang/rust#43081)
However, once https://github.com/rust-lang/rust/pull/73084 is merged,
these groups will be present in more cases. This commit makes `clap`
compatible with both older and newer versions of rustc.
This PR switches the Arg::Short macro to take a character instead of a string. It removes the hacky code in the Method to_token method and implements the logic for Short when parsing the clap derive arguments.
Fixes#1815.
