cli: Split jj squash into jj squash and jj movediff

As has been discussed in several places, `jj squash` is a very
complicated command that can do many things.

`jj movediff` is much simpler to explain ("moves diffs from one commit
to another").

It is implemented in terms of squash because the difference between the
two is more semantic than programatic.

In the future, we *may* consider removing the ability for squash to
operate on individual files, but that is still hotly debated.

Author: matts1

CHANGELOG.md

@@ -66,6 +66,8 @@ to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
   tags. These keywords may be useful in non-colocated Git repositories where
   local and exported `@git` tags can point to different revisions.
 
+* `jj amend` moves diffs between revisions, (similar to squash)
+
 ### Fixed bugs
 
 * `jj metaedit --author-timestamp` twice with the same value no longer

cli/src/commands/mod.rs

@@ -108,6 +108,7 @@ enum Command {
     Describe(describe::DescribeArgs),
     Diff(diff::DiffArgs),
     Diffedit(diffedit::DiffeditArgs),
+    Amend(squash::AmendArgs),
     Duplicate(duplicate::DuplicateArgs),
     Edit(edit::EditArgs),
     #[command(alias = "obslog", visible_alias = "evolution-log")]
@@ -180,6 +181,11 @@ pub fn run_command(ui: &mut Ui, command_helper: &CommandHelper) -> Result<(), Co
         Command::Describe(args) => describe::cmd_describe(ui, command_helper, args),
         Command::Diff(args) => diff::cmd_diff(ui, command_helper, args),
         Command::Diffedit(args) => diffedit::cmd_diffedit(ui, command_helper, args),
+        Command::Amend(args) => squash::cmd_squash_or_amend(
+            ui,
+            command_helper,
+            squash::SquashOrAmendArgs::AmendArgs(args),
+        ),
         Command::Duplicate(args) => duplicate::cmd_duplicate(ui, command_helper, args),
         Command::Edit(args) => edit::cmd_edit(ui, command_helper, args),
         Command::Evolog(args) => evolog::cmd_evolog(ui, command_helper, args),
@@ -212,7 +218,11 @@ pub fn run_command(ui: &mut Ui, command_helper: &CommandHelper) -> Result<(), Co
         Command::Sign(args) => sign::cmd_sign(ui, command_helper, args),
         Command::Sparse(args) => sparse::cmd_sparse(ui, command_helper, args),
         Command::Split(args) => split::cmd_split(ui, command_helper, args),
-        Command::Squash(args) => squash::cmd_squash(ui, command_helper, args),
+        Command::Squash(args) => squash::cmd_squash_or_amend(
+            ui,
+            command_helper,
+            squash::SquashOrAmendArgs::SquashArgs(args),
+        ),
         Command::Status(args) => status::cmd_status(ui, command_helper, args),
         Command::Tag(args) => tag::cmd_tag(ui, command_helper, args),
         Command::Undo(args) => undo::cmd_undo(ui, command_helper, args),

cli/src/commands/squash.rs

@@ -47,7 +47,11 @@ use crate::description_util::join_message_paragraphs;
 use crate::description_util::try_combine_messages;
 use crate::ui::Ui;
 
-/// Move changes from a revision into another revision
+/// Combine revisions by moving changes from a revision into another revision.
+///
+/// Note: If you aren't trying to merge the revision metadata
+/// (eg. description, bookmarks), or if you want to do a partial squash,
+/// you probably want `jj amend`.
 ///
 /// With the `-r` option, moves the changes from the specified revision to the
 /// parent revision. Fails if there are several parent revisions (i.e., the
@@ -59,8 +63,8 @@ use crate::ui::Ui;
 /// commit to the grandparent.
 ///
 /// If, after moving changes out, the source revision is empty compared to its
-/// parent(s), and `--keep-emptied` is not set, it will be abandoned. Without
-/// `--interactive` or paths, the source revision will always be empty.
+/// parent(s), it will be abandoned. Without `--interactive` or paths, the
+/// source revision will always be empty.
 ///
 /// If the source was abandoned and both the source and destination had a
 /// non-empty description, you will be asked for the combined description. If
@@ -76,34 +80,17 @@ use crate::ui::Ui;
 /// (if no `--from` is specified, `--from @` is assumed).
 #[derive(clap::Args, Clone, Debug)]
 pub(crate) struct SquashArgs {
-    /// Revision to squash into its parent (default: @). Incompatible with the
-    /// experimental `-d`/`-A`/`-B` options.
-    #[arg(
-        long,
-        short,
-        value_name = "REVSET",
-        add = ArgValueCompleter::new(complete::revset_expression_mutable),
-    )]
-    revision: Option<RevisionArg>,
+    #[clap(flatten)]
+    pub(crate) common: CommonArgs,
 
-    /// Revision(s) to squash from (default: @)
-    #[arg(
-        long, short,
-        conflicts_with = "revision",
-        value_name = "REVSETS",
-        add = ArgValueCompleter::new(complete::revset_expression_mutable),
-    )]
-    from: Vec<RevisionArg>,
+    /// The description to use for squashed revision (don't open editor)
+    #[arg(long = "message", short, value_name = "MESSAGE")]
+    pub(crate) message_paragraphs: Vec<String>,
 
-    /// Revision to squash into (default: @)
-    #[arg(
-        long, short = 't',
-        conflicts_with = "revision",
-        visible_alias = "to",
-        value_name = "REVSET",
-        add = ArgValueCompleter::new(complete::revset_expression_mutable),
-    )]
-    into: Option<RevisionArg>,
+    /// Use the description of the destination revision and discard the
+    /// description(s) of the source revision(s)
+    #[arg(long, short, conflicts_with = "message_paragraphs")]
+    pub(crate) use_destination_message: bool,
 
     /// (Experimental) The revision(s) to use as parent for the new commit (can
     /// be repeated to create a merge commit)
@@ -145,14 +132,67 @@ pub(crate) struct SquashArgs {
     )]
     insert_before: Option<Vec<RevisionArg>>,
 
-    /// The description to use for squashed revision (don't open editor)
+    /// The source revision will not be abandoned
+    #[arg(long, short)]
+    keep_emptied: bool,
+}
+
+/// Move changes from a revision into another revision
+///
+/// With the `-r` option, moves the changes from the specified revision to the
+/// parent revision. Fails if there are several parent revisions (i.e., the
+/// given revision is a merge).
+///
+/// With the `--from` and/or `--into` options, moves changes from/to the given
+/// revisions. If either is left out, it defaults to the working-copy commit.
+/// For example, `jj squash --into @--` moves changes from the working-copy
+/// commit to the grandparent.
+///
+/// EXPERIMENTAL FEATURES
+///
+/// An alternative squashing UI is available via the `-d`, `-A`, and `-B`
+/// options. They can be used together with one or more `--from` options
+/// (if no `--from` is specified, `--from @` is assumed).
+#[derive(clap::Args, Clone, Debug)]
+pub(crate) struct AmendArgs {
+    #[clap(flatten)]
+    common: CommonArgs,
+
+    /// The description to overwrite for the destination revision.
     #[arg(long = "message", short, value_name = "MESSAGE")]
-    message_paragraphs: Vec<String>,
+    pub(crate) message_paragraphs: Vec<String>,
+}
 
-    /// Use the description of the destination revision and discard the
-    /// description(s) of the source revision(s)
-    #[arg(long, short, conflicts_with = "message_paragraphs")]
-    use_destination_message: bool,
+#[derive(clap::Args, Clone, Debug)]
+pub(crate) struct CommonArgs {
+    /// Revision to squash into its parent (default: @). Incompatible with the
+    /// experimental `-d`/`-A`/`-B` options.
+    #[arg(
+        long,
+        short,
+        value_name = "REVSET",
+        add = ArgValueCompleter::new(complete::revset_expression_mutable),
+    )]
+    revision: Option<RevisionArg>,
+
+    /// Revision(s) to squash from (default: @)
+    #[arg(
+        long, short,
+        conflicts_with = "revision",
+        value_name = "REVSETS",
+        add = ArgValueCompleter::new(complete::revset_expression_mutable),
+    )]
+    from: Vec<RevisionArg>,
+
+    /// Revision to squash into (default: @)
+    #[arg(
+        long, short = 't',
+        conflicts_with = "revision",
+        visible_alias = "to",
+        value_name = "REVSET",
+        add = ArgValueCompleter::new(complete::revset_expression_mutable),
+    )]
+    into: Option<RevisionArg>,
 
     /// Interactively choose which parts to squash
     #[arg(long, short)]
@@ -173,20 +213,59 @@ pub(crate) struct SquashArgs {
         add = ArgValueCompleter::new(complete::squash_revision_files),
     )]
     paths: Vec<String>,
+}
 
-    /// The source revision will not be abandoned
-    #[arg(long, short)]
-    keep_emptied: bool,
+pub(crate) enum SquashOrAmendArgs<'a> {
+    SquashArgs(&'a SquashArgs),
+    AmendArgs(&'a AmendArgs),
 }
 
 #[instrument(skip_all)]
-pub(crate) fn cmd_squash(
+pub(crate) fn cmd_squash_or_amend(
     ui: &mut Ui,
     command: &CommandHelper,
-    args: &SquashArgs,
+    args: SquashOrAmendArgs,
 ) -> Result<(), CommandError> {
+    let keep_emptied = match args {
+        SquashOrAmendArgs::SquashArgs(args) => {
+            if args.keep_emptied {
+                writeln!(
+                    ui.warning_default(),
+                    "`jj squash --keep-emptied` has been deprecated and replaced with `jj amend`",
+                )?;
+            }
+            args.keep_emptied
+        }
+        SquashOrAmendArgs::AmendArgs(_) => true,
+    };
+    let message_paragraphs = match args {
+        SquashOrAmendArgs::SquashArgs(args) => &args.message_paragraphs,
+        SquashOrAmendArgs::AmendArgs(args) => &args.message_paragraphs,
+    };
+    let use_destination_message = match args {
+        SquashOrAmendArgs::SquashArgs(args) => args.use_destination_message,
+        SquashOrAmendArgs::AmendArgs(_) => Default::default(),
+    };
+    let insert_before = match args {
+        SquashOrAmendArgs::SquashArgs(args) => &args.insert_before,
+        SquashOrAmendArgs::AmendArgs(_) => &None,
+    };
+    let insert_after = match args {
+        SquashOrAmendArgs::SquashArgs(args) => &args.insert_after,
+        SquashOrAmendArgs::AmendArgs(_) => &None,
+    };
+    let destination = match args {
+        SquashOrAmendArgs::SquashArgs(args) => &args.destination,
+        SquashOrAmendArgs::AmendArgs(_) => &None,
+    };
+
+    let args = match args {
+        SquashOrAmendArgs::SquashArgs(args) => &args.common,
+        SquashOrAmendArgs::AmendArgs(args) => &args.common,
+    };
+
     let insert_destination_commit =
-        args.destination.is_some() || args.insert_after.is_some() || args.insert_before.is_some();
+        destination.is_some() || insert_after.is_some() || insert_before.is_some();
 
     let mut workspace_command = command.workspace_helper(ui)?;
 
@@ -253,9 +332,9 @@ pub(crate) fn cmd_squash(
         let (parent_ids, child_ids) = compute_commit_location(
             ui,
             tx.base_workspace_helper(),
-            args.destination.as_deref(),
-            args.insert_after.as_deref(),
-            args.insert_before.as_deref(),
+            destination.as_deref(),
+            insert_after.as_deref(),
+            insert_before.as_deref(),
             "squashed commit",
         )?;
         let parent_commits: Vec<_> = parent_ids
@@ -310,15 +389,12 @@ pub(crate) fn cmd_squash(
         tx.base_workspace_helper()
             .diff_selector(ui, args.tool.as_deref(), args.interactive)?;
     let text_editor = tx.base_workspace_helper().text_editor()?;
-    let description = SquashedDescription::from_args(args);
+    let description = SquashedDescription::from_args(message_paragraphs, use_destination_message);
 
     let source_commits = select_diff(&tx, &sources, &destination, &matcher, &diff_selector)?;
-    if let Some(squashed) = rewrite::squash_commits(
-        tx.repo_mut(),
-        &source_commits,
-        &destination,
-        args.keep_emptied,
-    )? {
+    if let Some(squashed) =
+        rewrite::squash_commits(tx.repo_mut(), &source_commits, &destination, keep_emptied)?
+    {
         let mut commit_builder = squashed.commit_builder.detach();
         let new_description = match description {
             SquashedDescription::Exact(description) => {
@@ -434,14 +510,14 @@ enum SquashedDescription {
 }
 
 impl SquashedDescription {
-    fn from_args(args: &SquashArgs) -> Self {
+    fn from_args(message_paragraphs: &[String], use_destination_message: bool) -> Self {
         // These options are incompatible and Clap is configured to prevent this.
-        assert!(args.message_paragraphs.is_empty() || !args.use_destination_message);
+        assert!(message_paragraphs.is_empty() || !use_destination_message);
 
-        if !args.message_paragraphs.is_empty() {
-            let desc = join_message_paragraphs(&args.message_paragraphs);
+        if !message_paragraphs.is_empty() {
+            let desc = join_message_paragraphs(message_paragraphs);
             Self::Exact(desc)
-        } else if args.use_destination_message {
+        } else if use_destination_message {
             Self::UseDestination
         } else {
             Self::Combine

cli/tests/[email protected]

@@ -36,6 +36,7 @@ This document contains the help content for the `jj` command-line program.
 * [`jj describe`↴](#jj-describe)
 * [`jj diff`↴](#jj-diff)
 * [`jj diffedit`↴](#jj-diffedit)
+* [`jj amend`↴](#jj-amend)
 * [`jj duplicate`↴](#jj-duplicate)
 * [`jj edit`↴](#jj-edit)
 * [`jj evolog`↴](#jj-evolog)
@@ -141,6 +142,7 @@ To get started, see the tutorial [`jj help -k tutorial`].
 * `describe` — Update the change description or other metadata [default alias: desc]
 * `diff` — Compare file contents between two revisions
 * `diffedit` — Touch up the content changes in a revision with a diff editor
+* `amend` — Move changes from a revision into another revision
 * `duplicate` — Create new changes with the same content as existing ones
 * `edit` — Sets the specified revision as the working-copy revision
 * `evolog` — Show how a change has evolved over time
@@ -168,7 +170,7 @@ To get started, see the tutorial [`jj help -k tutorial`].
 * `simplify-parents` — Simplify parent edges for the specified revision(s)
 * `sparse` — Manage which paths from the working-copy commit are present in the working copy
 * `split` — Split a revision in two
-* `squash` — Move changes from a revision into another revision
+* `squash` — Combine revisions by moving changes from a revision into another revision
 * `status` — Show high-level repo status [default alias: st]
 * `tag` — Manage tags
 * `undo` — Undo the last operation
@@ -909,6 +911,35 @@ See `jj restore` if you want to move entire files from one revision to another.
 
 
 
+## `jj amend`
+
+Move changes from a revision into another revision
+
+With the `-r` option, moves the changes from the specified revision to the parent revision. Fails if there are several parent revisions (i.e., the given revision is a merge).
+
+With the `--from` and/or `--into` options, moves changes from/to the given revisions. If either is left out, it defaults to the working-copy commit. For example, `jj squash --into @--` moves changes from the working-copy commit to the grandparent.
+
+EXPERIMENTAL FEATURES
+
+An alternative squashing UI is available via the `-d`, `-A`, and `-B` options. They can be used together with one or more `--from` options (if no `--from` is specified, `--from @` is assumed).
+
+**Usage:** `jj amend [OPTIONS] [FILESETS]...`
+
+###### **Arguments:**
+
+* `<FILESETS>` — Move only changes to these paths (instead of all paths)
+
+###### **Options:**
+
+* `-r`, `--revision <REVSET>` — Revision to squash into its parent (default: @). Incompatible with the experimental `-d`/`-A`/`-B` options
+* `-f`, `--from <REVSETS>` — Revision(s) to squash from (default: @)
+* `-t`, `--into <REVSET>` [alias: `to`] — Revision to squash into (default: @)
+* `-i`, `--interactive` — Interactively choose which parts to squash
+* `--tool <NAME>` — Specify diff editor to be used (implies --interactive)
+* `-m`, `--message <MESSAGE>` — The description to overwrite for the destination revision
+
+
+
 ## `jj duplicate`
 
 Create new changes with the same content as existing ones
@@ -2715,13 +2746,15 @@ Splitting an empty commit is not supported because the same effect can be achiev
 
 ## `jj squash`
 
-Move changes from a revision into another revision
+Combine revisions by moving changes from a revision into another revision.
+
+Note: If you aren't trying to merge the revision metadata (eg. description, bookmarks), or if you want to do a partial squash, you probably want `jj amend`.
 
 With the `-r` option, moves the changes from the specified revision to the parent revision. Fails if there are several parent revisions (i.e., the given revision is a merge).
 
 With the `--from` and/or `--into` options, moves changes from/to the given revisions. If either is left out, it defaults to the working-copy commit. For example, `jj squash --into @--` moves changes from the working-copy commit to the grandparent.
 
-If, after moving changes out, the source revision is empty compared to its parent(s), and `--keep-emptied` is not set, it will be abandoned. Without `--interactive` or paths, the source revision will always be empty.
+If, after moving changes out, the source revision is empty compared to its parent(s), it will be abandoned. Without `--interactive` or paths, the source revision will always be empty.
 
 If the source was abandoned and both the source and destination had a non-empty description, you will be asked for the combined description. If either was empty, then the other one will be used.
 
@@ -2742,13 +2775,13 @@ An alternative squashing UI is available via the `-d`, `-A`, and `-B` options. T
 * `-r`, `--revision <REVSET>` — Revision to squash into its parent (default: @). Incompatible with the experimental `-d`/`-A`/`-B` options
 * `-f`, `--from <REVSETS>` — Revision(s) to squash from (default: @)
 * `-t`, `--into <REVSET>` [alias: `to`] — Revision to squash into (default: @)
+* `-i`, `--interactive` — Interactively choose which parts to squash
+* `--tool <NAME>` — Specify diff editor to be used (implies --interactive)
+* `-m`, `--message <MESSAGE>` — The description to use for squashed revision (don't open editor)
+* `-u`, `--use-destination-message` — Use the description of the destination revision and discard the description(s) of the source revision(s)
 * `-d`, `--destination <REVSETS>` — (Experimental) The revision(s) to use as parent for the new commit (can be repeated to create a merge commit)
 * `-A`, `--insert-after <REVSETS>` [alias: `after`] — (Experimental) The revision(s) to insert the new commit after (can be repeated to create a merge commit)
 * `-B`, `--insert-before <REVSETS>` [alias: `before`] — (Experimental) The revision(s) to insert the new commit before (can be repeated to create a merge commit)
-* `-m`, `--message <MESSAGE>` — The description to use for squashed revision (don't open editor)
-* `-u`, `--use-destination-message` — Use the description of the destination revision and discard the description(s) of the source revision(s)
-* `-i`, `--interactive` — Interactively choose which parts to squash
-* `--tool <NAME>` — Specify diff editor to be used (implies --interactive)
 * `-k`, `--keep-emptied` — The source revision will not be abandoned