cli: duplicate: deprecate positional revisions argument

Since the interface is now quite similar to "jj rebase", I think it's better to
require "-r". We might want to add "--source"/"--branch" later.

CHANGELOG.md

@@ -12,6 +12,8 @@ to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ### Deprecations
 
+* `jj duplicate REV` is deprecated in favor of `-r REV`.
+
 ### New features
 
 ### Fixed bugs

cli/src/commands/duplicate.rs

@@ -52,10 +52,11 @@ use crate::ui::Ui;
 #[derive(clap::Args, Clone, Debug)]
 pub(crate) struct DuplicateArgs {
     /// The revision(s) to duplicate (default: @)
-    #[arg(value_name = "REVISIONS", add = ArgValueCandidates::new(complete::all_revisions))]
+    #[arg(short = 'r', long, add = ArgValueCandidates::new(complete::all_revisions))]
+    revisions: Vec<RevisionArg>,
+    // TODO: Delete revisions_pos in jj 0.30+
+    #[arg(hide = true, value_name = "REVISIONS")]
     revisions_pos: Vec<RevisionArg>,
-    #[arg(short = 'r', hide = true)]
-    revisions_opt: Vec<RevisionArg>,
     /// The revision(s) to duplicate onto (can be repeated to create a merge
     /// commit)
     #[arg(long, short, add = ArgValueCandidates::new(complete::all_revisions))]
@@ -89,10 +90,16 @@ pub(crate) fn cmd_duplicate(
     args: &DuplicateArgs,
 ) -> Result<(), CommandError> {
     let mut workspace_command = command.workspace_helper(ui)?;
+    if !args.revisions_pos.is_empty() {
+        writeln!(
+            ui.warning_default(),
+            "Positional argument is deprecated. Use -r REVISION instead."
+        )?;
+    }
     let to_duplicate: Vec<CommitId> =
-        if !args.revisions_pos.is_empty() || !args.revisions_opt.is_empty() {
+        if !args.revisions.is_empty() || !args.revisions_pos.is_empty() {
             workspace_command
-                .parse_union_revsets(ui, &[&*args.revisions_pos, &*args.revisions_opt].concat())?
+                .parse_union_revsets(ui, &[&*args.revisions, &*args.revisions_pos].concat())?
         } else {
             workspace_command.parse_revset(ui, &RevisionArg::AT)?
         }

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

@@ -751,14 +751,15 @@ When none of the `--destination`, `--insert-after`, or `--insert-before` argumen
 
 When any of the `--destination`, `--insert-after`, or `--insert-before` arguments are provided, the roots of the specified commits will be duplicated onto the destination indicated by the arguments. Other specified commits will be duplicated onto these newly duplicated commits. If the `--insert-after` or `--insert-before` arguments are provided, the new children indicated by the arguments will be rebased onto the heads of the specified commits.
 
-**Usage:** `jj duplicate [OPTIONS] [REVISIONS]...`
+**Usage:** `jj duplicate [OPTIONS]`
 
 ###### **Arguments:**
 
-* `<REVISIONS>` — The revision(s) to duplicate (default: @)
+* `<REVISIONS>`
 
 ###### **Options:**
 
+* `-r`, `--revisions <REVISIONS>` — The revision(s) to duplicate (default: @)
 * `-d`, `--destination <DESTINATION>` — The revision(s) to duplicate onto (can be repeated to create a merge commit)
 * `-A`, `--insert-after <INSERT_AFTER>` — The revision(s) to insert after (can be repeated to create a merge commit)
 * `-B`, `--insert-before <INSERT_BEFORE>` — The revision(s) to insert before (can be repeated to create a merge commit)

cli/tests/test_commit_template.rs

@@ -993,7 +993,7 @@ fn test_short_prefix_in_transaction() {
     }
     // Create 2^4 duplicates of the chain
     for _ in 0..4 {
-        test_env.jj_cmd_ok(&repo_path, &["duplicate", "description(commit)"]);
+        test_env.jj_cmd_ok(&repo_path, &["duplicate", "-rdescription(commit)"]);
     }
 
     // Short prefix should be used for commit summary inside the transaction