cmd: Add --to and --from arguments to jj touchup

This allows touching up a commit while seeing the differences between it and
another arbitrary commit.

src/commands.rs

@@ -537,19 +537,34 @@ struct RestoreArgs {
     paths: Vec<String>,
 }
 
-/// Touch up the content changes in a revision
+/// Touch up the content changes in a revision with a diff editor
+///
+/// With the `-r` option, which is the default, starts a diff editor (`meld` by
+/// default) on the changes in the revision.
+///
+/// With the `--from` and/or `--to` options, starts a diff editor comparing the
+/// "from" revision to the "to" revision.
 ///
-/// Starts a diff editor (`meld` by default) on the changes in the revision.
 /// Edit the right side of the diff until it looks the way you want. Once you
-/// close the editor, the revision will be updated. Descendants will be rebased
-/// on top as usual, which may result in conflicts. See `jj squash -i` or `jj
-/// unsquash -i` if you instead want to move changes into or out of the parent
-/// revision.
+/// close the editor, the revision specified with `-r` or `--to` will be
+/// updated. Descendants will be rebased on top as usual, which may result in
+/// conflicts.
+///
+/// See `jj restore` if you want to move entire files from one revision to
+/// another. See `jj squash -i` or `jj unsquash -i` if you instead want to move
+/// changes into or out of the parent revision.
 #[derive(clap::Args, Clone, Debug)]
 struct TouchupArgs {
-    /// The revision to touch up
-    #[arg(long, short, default_value = "@")]
-    revision: RevisionArg,
+    /// The revision to touch up. Defaults to @ if --to/--from are not
+    /// specified.
+    #[arg(long, short)]
+    revision: Option<RevisionArg>,
+    /// Show changes from this revision. Defaults to @ if --to is specified.
+    #[arg(long, conflicts_with = "revision")]
+    from: Option<RevisionArg>,
+    /// Edit changes in this revision. Defaults to @ if --from is specified.
+    #[arg(long, conflicts_with = "revision")]
+    to: Option<RevisionArg>,
 }
 
 /// Split a revision in two
@@ -2408,27 +2423,47 @@ fn cmd_touchup(
     args: &TouchupArgs,
 ) -> Result<(), CommandError> {
     let mut workspace_command = command.workspace_helper(ui)?;
-    let commit = workspace_command.resolve_single_rev(&args.revision)?;
-    workspace_command.check_rewriteable(&commit)?;
-    let base_tree = merge_commit_trees(workspace_command.repo().as_repo_ref(), &commit.parents());
+
+    let (target_commit, base_commits, diff_description);
+    if args.from.is_some() || args.to.is_some() {
+        target_commit = workspace_command.resolve_single_rev(args.to.as_deref().unwrap_or("@"))?;
+        base_commits =
+            vec![workspace_command.resolve_single_rev(args.from.as_deref().unwrap_or("@"))?];
+        diff_description = format!(
+            "The diff initially shows the commit's changes relative to:\n{}",
+            short_commit_description(&base_commits[0])
+        );
+    } else {
+        target_commit =
+            workspace_command.resolve_single_rev(args.revision.as_deref().unwrap_or("@"))?;
+        base_commits = target_commit.parents();
+        diff_description = "The diff initially shows the commit's changes.".to_string();
+    };
+    workspace_command.check_rewriteable(&target_commit)?;
+
     let instructions = format!(
         "\
 You are editing changes in: {}
 
-The diff initially shows the commit's changes.
+{diff_description}
 
 Adjust the right side until it shows the contents you want. If you
 don't make any changes, then the operation will be aborted.",
-        short_commit_description(&commit)
+        short_commit_description(&target_commit),
     );
-    let tree_id = workspace_command.edit_diff(ui, &base_tree, &commit.tree(), &instructions)?;
-    if &tree_id == commit.tree_id() {
+    let base_tree = merge_commit_trees(
+        workspace_command.repo().as_repo_ref(),
+        base_commits.as_slice(),
+    );
+    let tree_id =
+        workspace_command.edit_diff(ui, &base_tree, &target_commit.tree(), &instructions)?;
+    if &tree_id == target_commit.tree_id() {
         ui.write("Nothing changed.\n")?;
     } else {
-        let mut tx =
-            workspace_command.start_transaction(&format!("edit commit {}", commit.id().hex()));
+        let mut tx = workspace_command
+            .start_transaction(&format!("edit commit {}", target_commit.id().hex()));
         let mut_repo = tx.mut_repo();
-        let new_commit = CommitBuilder::for_rewrite_from(ui.settings(), &commit)
+        let new_commit = CommitBuilder::for_rewrite_from(ui.settings(), &target_commit)
             .set_tree(tree_id)
             .write_to_repo(mut_repo);
         ui.write("Created ")?;

tests/test_global_opts.rs

@@ -263,12 +263,14 @@ fn test_help() {
 
     let stdout = test_env.jj_cmd_success(test_env.env_root(), &["touchup", "-h"]);
     insta::assert_snapshot!(stdout, @r###"
-    Touch up the content changes in a revision
+    Touch up the content changes in a revision with a diff editor
 
     Usage: jj touchup [OPTIONS]
 
     Options:
-      -r, --revision <REVISION>  The revision to touch up [default: @]
+      -r, --revision <REVISION>  The revision to touch up. Defaults to @ if --to/--from are not specified
+          --from <FROM>          Show changes from this revision. Defaults to @ if --to is specified
+          --to <TO>              Edit changes in this revision. Defaults to @ if --from is specified
       -h, --help                 Print help information (use `--help` for more detail)
 
     Global Options:

tests/test_touchup_command.rs

@@ -25,6 +25,7 @@ fn test_touchup() {
     let repo_path = test_env.env_root().join("repo");
 
     std::fs::write(repo_path.join("file1"), "a\n").unwrap();
+    test_env.jj_cmd_success(&repo_path, &["new"]);
     std::fs::write(repo_path.join("file2"), "a\n").unwrap();
     std::fs::write(repo_path.join("file3"), "a\n").unwrap();
     test_env.jj_cmd_success(&repo_path, &["new"]);
@@ -66,8 +67,8 @@ fn test_touchup() {
     std::fs::write(&edit_script, "reset file2").unwrap();
     let stdout = test_env.jj_cmd_success(&repo_path, &["touchup"]);
     insta::assert_snapshot!(stdout, @r###"
-    Created 8c79910b5033 (no description set)
-    Working copy now at: 8c79910b5033 (no description set)
+    Created 1930da4a57e9 (no description set)
+    Working copy now at: 1930da4a57e9 (no description set)
     Added 0 files, modified 1 files, removed 0 files
     "###);
     let stdout = test_env.jj_cmd_success(&repo_path, &["diff", "-s"]);
@@ -80,15 +81,34 @@ fn test_touchup() {
     std::fs::write(&edit_script, "write file3\nmodified\n").unwrap();
     let stdout = test_env.jj_cmd_success(&repo_path, &["touchup", "-r", "@-"]);
     insta::assert_snapshot!(stdout, @r###"
-    Created 472de2debaff (no description set)
+    Created c03ae96780b6 (no description set)
     Rebased 1 descendant commits
-    Working copy now at: 6d19dc1ea106 (no description set)
+    Working copy now at: 2a4dc204a6ab (no description set)
     Added 0 files, modified 1 files, removed 0 files
     "###);
     let contents = String::from_utf8(std::fs::read(repo_path.join("file3")).unwrap()).unwrap();
     insta::assert_snapshot!(contents, @r###"
     modified
     "###);
+
+    // Test touchup --from @--
+    test_env.jj_cmd_success(&repo_path, &["undo"]);
+    std::fs::write(
+        &edit_script,
+        "files-before file1\0files-after JJ-INSTRUCTIONS file2 file3\0reset file2",
+    )
+    .unwrap();
+    let stdout = test_env.jj_cmd_success(&repo_path, &["touchup", "--from", "@--"]);
+    insta::assert_snapshot!(stdout, @r###"
+    Created 15f2c966d508 (no description set)
+    Working copy now at: 15f2c966d508 (no description set)
+    Added 0 files, modified 0 files, removed 1 files
+    "###);
+    let stdout = test_env.jj_cmd_success(&repo_path, &["diff", "-s"]);
+    insta::assert_snapshot!(stdout, @r###"
+    R file1
+    R file2
+    "###);
 }
 
 #[test]