rust_2015 and rust_2018 are just re-exports of v1.
rust_2021 is a module that for now just re-exports everything from v1,
such that we can add more things later.

Co-authored-by: Joshua Nelson <joshua@yottadb.com>

enableSearchInput was called from two places:

- setupSearchLoader
- addSearchOptions, which is itself called from setupSearchLoader only

This commit can safely get rid of the addSearchOptions calls entirely,
and since the setupSearchLoader call is immediately preceded by other
method calls on search_input, there's no need to check if it's set.

This switches Rust's WASI target to use crt1-command.o instead of
crt1.o, which enables support for new-style commands. By default,
new-style commands work the same way as old-style commands, so nothing
immediately changes here, but this will be needed by later changes to
enable support for typed arguments.

See here for more information on new-style commands:
 - WebAssembly/wasi-libc#203
 - https://reviews.llvm.org/D81689

This is a breaking change for cases where the environment is
accessed in a Command::pre_exec closure. Except for
single-threaded programs these uses were not correct
anyway since they aren't async-signal safe.

"The Rust Standard LibraryThe Rust Standard Library is the …" is an awful description.

It's kinda silly using serde seq for fixed-length stuff.

…akis

always eagerly eval consts in Relate

r? ```@nikomatsakis``` cc ```@varkor```

…akis

Edition-specific preludes

This changes `{std,core}::prelude` to export edition-specific preludes under `rust_2015`, `rust_2018` and `rust_2021`. (As suggested in rust-lang#51418 (comment).) For now they all just re-export `v1::*`, but this allows us to add things to the 2021edition prelude soon.

This also changes the compiler to make the automatically injected prelude import dependent on the selected edition.

cc `@rust-lang/libs` `@djc`

rustdoc: Remove redundant enableSearchInput function

enableSearchInput was called from two places:

- setupSearchLoader
- addSearchOptions, which is itself called from setupSearchLoader only

This commit can safely get rid of the addSearchOptions calls entirely, and since the setupSearchLoader call is immediately preceded by other method calls on search_input, there's no need to check if it's set.

…chton

WASI: Switch to crt1-command.o to enable support for new-style commands

This switches Rust's WASI target to use crt1-command.o instead of
crt1.o, which enables support for new-style commands. By default,
new-style commands work the same way as old-style commands, so nothing
immediately changes here, but this will be needed by later changes to
enable support for typed arguments.

See here for more information on new-style commands:
 - WebAssembly/wasi-libc#203
 - https://reviews.llvm.org/D81689

r? ```@alexcrichton```

…oshtriplett

Do not attempt to unlock envlock in child process after a fork.

This implements the first two points from rust-lang#64718 (comment)

This is a breaking change for cases where the environment is accessed in a Command::pre_exec closure. Except for single-threaded programs these uses were not correct anyway since they aren't async-signal safe.

Note that we had a ui test that explicitly tried `env::set_var` in `pre_exec`. As expected it failed with these changes when I tested locally.

fix: wrong word

Treat header as first paragraph for shortened markdown descriptions

"The Rust Standard LibraryThe Rust Standard Library is the …" is an awful description.

…-obk

fix error message for copy(_nonoverlapping) overflow

Fixes an error message regression introduced in rust-lang#77511 (and adds tests).

r? `@oli-obk`

…ou-se

Rename `Option::get_or_default` to `get_or_insert_default`

...as [suggested](rust-lang#82901 (comment)) by `@m-ou-se.` In hindsight this seems rather obvious, at least to me.

r? `@joshtriplett`