refactor(rust)!: merge cargo and rustup plugins into rust plugin (#10270)

BREAKING CHANGE: `cargo` and `rustup` plugins have been moved to the `rust` plugin
since they're part of the Rust toolchain. If you're using these, update your .zshrc
file to use `rust` instead.

Closes #10270

Co-authored-by: Marc Cornellà <hello@mcornella.com>

plugins/rustup/README.md

@@ -1,9 +1,3 @@
 # rustup
 
-This plugin adds completion for [`rustup`](https://rustup.rs/), the toolchain installer for the Rust programming language.
-
-To use it, add `rustup` to the plugins array in your zshrc file:
-
-```zsh
-plugins=(... rustup)
-```
+**Deprecated: use the [`rust`](https://github.com/ohmyzsh/ohmyzsh/tree/master/plugins/rust) plugin instead.**

plugins/rustup/rustup.plugin.zsh

@@ -1,24 +1,11 @@
-if (( ! $+commands[rustup] )); then
-  return
-fi
+print ${(%):-'%F{yellow}The `rustup` plugin is deprecated and has been moved to the `rust` plugin.'}
+print ${(%):-'Please update your .zshrc to use the `%Brust%b` plugin instead.%f'}
 
 # Remove old generated completion file
-# TODO: 2021-09-15: remove this line
+# TODO: 2021-12-28: remove this line
 command rm -f "${0:A:h}/_rustup"
 
-# Add completions/ folder in $ZSH_CACHE_DIR
-comp_file="$ZSH_CACHE_DIR/completions/_rustup"
-command mkdir -p "${comp_file:h}"
-(( ${fpath[(Ie)"$ZSH_CACHE_DIR/completions"]} )) || fpath=("$ZSH_CACHE_DIR/completions" $fpath)
-
-# If the completion file doesn't exist yet, we need to autoload it and
-# bind it to `rustup`. Otherwise, compinit will have already done that
-if [[ ! -f "$comp_file" ]]; then
-  autoload -Uz _rustup
-  declare -A _comps
-  _comps[rustup]=_rustup
-fi
-
-# Generate completion file in the background
-rustup completions zsh >| "$comp_file" &|
-unset comp_file
+(( ${fpath[(Ie)$ZSH/plugins/rust]} )) || {
+  fpath=("$ZSH/plugins/rust" $fpath)
+  source "$ZSH/plugins/rust/rust.plugin.zsh"
+}