cli: completion: derive clap::ValueEnum for ColorChoice

This enables autocompletion for `jj --color <TAB>`

cli/src/cli_util.rs

@@ -3128,7 +3128,7 @@ pub struct GlobalArgs {
 
 #[derive(clap::Args, Clone, Debug)]
 pub struct EarlyArgs {
-    /// When to colorize output (always, never, debug, auto)
+    /// When to colorize output
     #[arg(long, value_name = "WHEN", global = true)]
     pub color: Option<ColorChoice>,
     /// Silence non-primary command output

cli/src/ui.rs

@@ -27,7 +27,6 @@ use std::mem;
 use std::process::Child;
 use std::process::ChildStdin;
 use std::process::Stdio;
-use std::str::FromStr;
 use std::thread;
 use std::thread::JoinHandle;
 
@@ -35,8 +34,6 @@ use itertools::Itertools as _;
 use jj_lib::config::ConfigGetError;
 use jj_lib::config::StackedConfig;
 use os_pipe::PipeWriter;
-use serde::de::Deserialize as _;
-use serde::de::IntoDeserializer as _;
 use tracing::instrument;
 
 use crate::command_error::CommandError;
@@ -206,7 +203,7 @@ pub struct Ui {
     output: UiOutput,
 }
 
-#[derive(Clone, Copy, Debug, Eq, PartialEq, serde::Deserialize)]
+#[derive(Clone, Copy, Debug, Eq, PartialEq, serde::Deserialize, clap::ValueEnum)]
 #[serde(rename_all = "kebab-case")]
 pub enum ColorChoice {
     Always,
@@ -215,17 +212,6 @@ pub enum ColorChoice {
     Auto,
 }
 
-impl FromStr for ColorChoice {
-    type Err = String;
-
-    fn from_str(s: &str) -> Result<Self, Self::Err> {
-        // serde::de::value::Error is Box<str> wrapper. Map it to String to hide
-        // the implementation detail.
-        Self::deserialize(s.into_deserializer())
-            .map_err(|err: serde::de::value::Error| err.to_string())
-    }
-}
-
 impl fmt::Display for ColorChoice {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         let s = match self {

cli/tests/cli-reference@.md.snap

@@ -1,6 +1,7 @@
 ---
 source: cli/tests/test_generate_md_cli_help.rs
 description: "AUTO-GENERATED FILE, DO NOT EDIT. This cli reference is generated by a test as an `insta` snapshot. MkDocs includes this snapshot from docs/cli-reference.md."
+snapshot_kind: text
 ---
 <!-- BEGIN MARKDOWN-->
 
@@ -187,7 +188,10 @@ To get started, see the tutorial at https://jj-vcs.github.io/jj/latest/tutorial/
 
    It is possible to run mutating commands when loading the repo at an earlier operation. Doing that is equivalent to having run concurrent commands starting at the earlier operation. There's rarely a reason to do that, but it is possible.
 * `--debug` — Enable debug logging
-* `--color <WHEN>` — When to colorize output (always, never, debug, auto)
+* `--color <WHEN>` — When to colorize output
+
+  Possible values: `always`, `never`, `debug`, `auto`
+
 * `--quiet` — Silence non-primary command output
 
    For example, `jj file list` will still list files, but it won't tell you if the working copy was snapshotted or if descendants were rebased.

cli/tests/test_completion.rs

@@ -79,7 +79,7 @@ fn test_bookmark_names() {
     --ignore-immutable	Allow rewriting immutable commits
     --at-operation	Operation to load the repo at
     --debug	Enable debug logging
-    --color	When to colorize output (always, never, debug, auto)
+    --color	When to colorize output
     --quiet	Silence non-primary command output
     --no-pager	Disable the pager
     --config	Additional configuration options (can be repeated)

cli/tests/test_global_opts.rs

@@ -458,7 +458,8 @@ fn test_color_config() {
     // Invalid --color
     let stderr = test_env.jj_cmd_cli_error(&repo_path, &["log", "--color=foo"]);
     insta::assert_snapshot!(stderr, @r"
-    error: invalid value 'foo' for '--color <WHEN>': unknown variant `foo`, expected one of `always`, `never`, `debug`, `auto`
+    error: invalid value 'foo' for '--color <WHEN>'
+      [possible values: always, never, debug, auto]
 
     For more information, try '--help'.
     ");
@@ -935,7 +936,7 @@ fn test_help() {
     let test_env = TestEnvironment::default();
 
     let stdout = test_env.jj_cmd_success(test_env.env_root(), &["diffedit", "-h"]);
-    insta::assert_snapshot!(stdout, @r###"
+    insta::assert_snapshot!(stdout, @r"
     Touch up the content changes in a revision with a diff editor
 
     Usage: jj diffedit [OPTIONS]
@@ -954,12 +955,13 @@ fn test_help() {
           --ignore-immutable             Allow rewriting immutable commits
           --at-operation <AT_OPERATION>  Operation to load the repo at [aliases: at-op]
           --debug                        Enable debug logging
-          --color <WHEN>                 When to colorize output (always, never, debug, auto)
+          --color <WHEN>                 When to colorize output [possible values: always, never, debug,
+                                         auto]
           --quiet                        Silence non-primary command output
           --no-pager                     Disable the pager
           --config <NAME=VALUE>          Additional configuration options (can be repeated)
           --config-file <PATH>           Additional configuration files (can be repeated)
-    "###);
+    ");
 }
 
 #[test]