This commit applies rustfmt with rust-lang/rust's default settings to
files in src/libstd *that are not involved in any currently open PR* to
minimize merge conflicts. THe list of files involved in open PRs was
determined by querying GitHub's GraphQL API with this script:
https://gist.github.com/dtolnay/aa9c34993dc051a4f344d1b10e4487e8
With the list of files from the script in outstanding_files, the
relevant commands were:
$ find src/libstd -name '*.rs' \
| xargs rustfmt --edition=2018 --unstable-features --skip-children
$ rg libstd outstanding_files | xargs git checkout --
Repeating this process several months apart should get us coverage of
most of the rest of libstd.
To confirm no funny business:
$ git checkout $THIS_COMMIT^
$ git show --pretty= --name-only $THIS_COMMIT \
| xargs rustfmt --edition=2018 --unstable-features --skip-children
$ git diff $THIS_COMMIT # there should be no difference
This commit adds a `backtrace` module to the standard library, as
designed in [RFC 2504]. The `Backtrace` type is intentionally very
conservative, effectively only allowing capturing it and printing it.
Additionally this commit also adds a `backtrace` method to the `Error`
trait which defaults to returning `None`, as specified in [RFC 2504].
More information about the design here can be found in [RFC 2504] and in
the [tracking issue].
Implementation-wise this is all based on the `backtrace` crate and very
closely mirrors the `backtrace::Backtrace` type on crates.io. Otherwise
it's pretty standard in how it handles everything internally.
[RFC 2504]: https://github.com/rust-lang/rfcs/blob/master/text/2504-fix-error.md
[tracking issue]: https://github.com/rust-lang/rust/issues/53487
cc #53487
