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/cargo/README.md

 # cargo
 
-This plugin adds completion for the Rust build tool [`Cargo`](https://github.com/rust-lang/cargo).
-
-To use it, add `cargo` to the plugins array in your zshrc file:
-
-```zsh
-plugins=(... cargo)
-```
-
-Updated on March 3rd, 2019, from [Cargo 0.34.0](https://github.com/rust-lang/cargo/releases/tag/0.34.0).
+**Deprecated: use the [`rust`](https://github.com/ohmyzsh/ohmyzsh/tree/master/plugins/rust) plugin instead.**

plugins/cargo/cargo.plugin.zsh

-if ! (( $+commands[rustup] && $+commands[cargo] )); then
-  return
-fi
+print ${(%):-'%F{yellow}The `cargo` 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}/_cargo"
 
-# Add completions/ folder in $ZSH_CACHE_DIR
-comp_file="$ZSH_CACHE_DIR/completions/_cargo"
-command mkdir -p "${comp_file:h}"
-(( ${fpath[(Ie)"$ZSH_CACHE_DIR/completions"]} )) || fpath=("$ZSH_CACHE_DIR/completions" $fpath)
-
-# If the completion file doesn't exist yet, we need to autoload it and
-# bind it to `cargo`. Otherwise, compinit will have already done that
-if [[ ! -f "$comp_file" ]]; then
-  autoload -Uz _cargo
-  declare -A _comps
-  _comps[cargo]=_cargo
-fi
-
-# Generate completion file in the background
-rustup completions zsh cargo >| "$comp_file" &|
-unset comp_file
+(( ${fpath[(Ie)$ZSH/plugins/rust]} )) || {
+  fpath=("$ZSH/plugins/rust" $fpath)
+  source "$ZSH/plugins/rust/rust.plugin.zsh"
+}

plugins/rust/README.md

 # rust
 
-This plugin adds completion for [`rustc`](https://doc.rust-lang.org/rustc/index.html), the compiler for the Rust programming language.
+This plugin adds completion for [`rustc`](https://doc.rust-lang.org/rustc/index.html), the compiler for the Rust programming language, as well as for `rustup` and `cargo` if you have the Rust toolchain installed.
 
 To use it, add `rust` to the plugins array in your zshrc file:
 

plugins/rust/rust.plugin.zsh

+if ! (( $+commands[rustup] && $+commands[cargo] )); then
+  return
+fi
+
+# Add completions folder in $ZSH_CACHE_DIR
+# TODO: 2021-12-28: remove this bit of code as it exists in oh-my-zsh.sh
+command mkdir -p "$ZSH_CACHE_DIR/completions"
+(( ${fpath[(Ie)"$ZSH_CACHE_DIR/completions"]} )) || fpath=("$ZSH_CACHE_DIR/completions" $fpath)
+
+# If the completion file doesn't exist yet, we need to autoload it and
+# bind it to `cargo`. Otherwise, compinit will have already done that
+if [[ ! -f "$ZSH_CACHE_DIR/completions/_cargo" ]]; then
+  autoload -Uz _cargo
+  declare -A _comps
+  _comps[cargo]=_cargo
+fi
+
+# 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 "$ZSH_CACHE_DIR/completions/_rustup" ]]; then
+  autoload -Uz _rustup
+  declare -A _comps
+  _comps[rustup]=_rustup
+fi
+
+# Generate completion files in the background
+rustup completions zsh >| "$ZSH_CACHE_DIR/completions/_rustup" &|
+rustup completions zsh cargo >| "$ZSH_CACHE_DIR/completions/_cargo" &|

plugins/rustup/README.md

 # 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

-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"
+}