cli: merge op heads and snapshot working copy by "op log" by default

This partially reverts 543036c753 "cli: run 'op log' without loading repo or
merging concurrent ops." User can now get around the issue by --at-op=@
--ignore-working-copy.

cli/src/cli_util.rs

@@ -328,6 +328,12 @@ impl CommandHelper {
             .map_err(|err| map_workspace_load_error(err, self.global_args.repository.as_deref()))
     }
 
+    /// Returns true if the working copy to be loaded is writable, and therefore
+    /// should usually be snapshotted.
+    pub fn is_working_copy_writable(&self) -> bool {
+        self.is_at_head_operation() && !self.global_args.ignore_working_copy
+    }
+
     /// Returns true if the current operation is considered to be the head.
     pub fn is_at_head_operation(&self) -> bool {
         // TODO: should we accept --at-op=<head_id> as the head op? or should we

cli/src/commands/operation/log.rs

@@ -12,6 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+use std::slice;
+
 use jj_lib::op_walk;
 
 use crate::cli_util::{format_template, CommandHelper, LogContentFormat};
@@ -21,6 +23,10 @@ use crate::operation_templater::OperationTemplateLanguage;
 use crate::ui::Ui;
 
 /// Show the operation log
+///
+/// Like other commands, `jj op log` snapshots the current working-copy changes
+/// and merges concurrent operations. Use `--at-op=@ --ignore-working-copy` to
+/// inspect the current state without mutation.
 #[derive(clap::Args, Clone, Debug)]
 pub struct OperationLogArgs {
     /// Limit number of operations to show
@@ -49,40 +55,26 @@ pub fn cmd_op_log(
     command: &CommandHelper,
     args: &OperationLogArgs,
 ) -> Result<(), CommandError> {
-    // Don't load the repo so that the operation history can be inspected even
-    // with a corrupted repo state. For example, you can find the first bad
-    // operation id to be abandoned.
-    let workspace = command.load_workspace()?;
-    let repo_loader = workspace.repo_loader();
-    let head_op_str = command.global_args().at_operation.as_deref().unwrap_or("@");
-    let head_ops = if head_op_str == "@" {
-        // If multiple head ops can't be resolved without merging, let the
-        // current op be empty. Beware that resolve_op_for_load() will eliminate
-        // redundant heads whereas get_current_head_ops() won't.
-        let current_op = op_walk::resolve_op_for_load(repo_loader, head_op_str).ok();
-        if let Some(op) = current_op {
-            vec![op]
-        } else {
-            op_walk::get_current_head_ops(
-                repo_loader.op_store(),
-                repo_loader.op_heads_store().as_ref(),
-            )?
-        }
+    let current_op = if command.is_working_copy_writable() {
+        let workspace_command = command.workspace_helper(ui)?;
+        workspace_command.repo().operation().clone()
     } else {
-        vec![op_walk::resolve_op_for_load(repo_loader, head_op_str)?]
-    };
-    let current_op_id = match &*head_ops {
-        [op] => Some(op.id()),
-        _ => None,
+        // Don't load the repo so that the operation history can be inspected
+        // even with a corrupted repo state. For example, you can find the first
+        // bad operation id to be abandoned.
+        let workspace = command.load_workspace()?;
+        command.resolve_operation(ui, workspace.repo_loader())?
     };
+    let op_store = current_op.op_store();
+
     let with_content_format = LogContentFormat::new(ui, command.settings())?;
 
     let template;
     let op_node_template;
     {
         let language = OperationTemplateLanguage::new(
-            repo_loader.op_store().root_operation_id(),
-            current_op_id,
+            op_store.root_operation_id(),
+            Some(current_op.id()),
             command.operation_template_extensions(),
         );
         let text = match &args.template {
@@ -117,7 +109,7 @@ pub fn cmd_op_log(
         )?;
     }
     let limit = args.limit.or(args.deprecated_limit).unwrap_or(usize::MAX);
-    let iter = op_walk::walk_ancestors(&head_ops).take(limit);
+    let iter = op_walk::walk_ancestors(slice::from_ref(&current_op)).take(limit);
     if !args.no_graph {
         let mut graph = get_graphlog(command.settings(), formatter.raw());
         for op in iter {

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

@@ -1335,6 +1335,8 @@ Compare changes to the repository between two operations
 
 Show the operation log
 
+Like other commands, `jj op log` snapshots the current working-copy changes and merges concurrent operations. Use `--at-op=@ --ignore-working-copy` to inspect the current state without mutation.
+
 **Usage:** `jj operation log [OPTIONS]`
 
 ###### **Options:**

cli/tests/test_concurrent_operations.rs

@@ -30,22 +30,19 @@ fn test_concurrent_operation_divergence() {
         &["describe", "-m", "message 2", "--at-op", "@-"],
     );
 
-    // "--at-op=@" disables op heads merging
-    let stderr = test_env.jj_cmd_failure(&repo_path, &["log", "--at-op=@"]);
+    // "--at-op=@" disables op heads merging, and prints head operation ids.
+    let stderr = test_env.jj_cmd_failure(&repo_path, &["op", "log", "--at-op=@"]);
     insta::assert_snapshot!(stderr, @r###"
     Error: The "@" expression resolved to more than one operation
     Hint: Try specifying one of the operations by ID: e31015019d90, 48f4a48f3f70
     "###);
 
-    // "op log" doesn't merge the concurrent operations
-    let stdout = test_env.jj_cmd_success(&repo_path, &["op", "log"]);
+    // "op log --at-op" should work without merging the head operations
+    let stdout = test_env.jj_cmd_success(&repo_path, &["op", "log", "--at-op=48f4a48f3f70"]);
     insta::assert_snapshot!(stdout, @r###"
-    ○  48f4a48f3f70 test-username@host.example.com 2001-02-03 04:05:09.000 +07:00 - 2001-02-03 04:05:09.000 +07:00
+    @  48f4a48f3f70 test-username@host.example.com 2001-02-03 04:05:09.000 +07:00 - 2001-02-03 04:05:09.000 +07:00
     │  describe commit 230dd059e1b059aefc0da06a2e5a7dbf22362f22
     │  args: jj describe -m 'message 2' --at-op @-
-    │ ○  e31015019d90 test-username@host.example.com 2001-02-03 04:05:08.000 +07:00 - 2001-02-03 04:05:08.000 +07:00
-    ├─╯  describe commit 230dd059e1b059aefc0da06a2e5a7dbf22362f22
-    │    args: jj describe -m 'message 1'
     ○  b51416386f26 test-username@host.example.com 2001-02-03 04:05:07.000 +07:00 - 2001-02-03 04:05:07.000 +07:00
     │  add workspace 'default'
     ○  9a7d829846af test-username@host.example.com 2001-02-03 04:05:07.000 +07:00 - 2001-02-03 04:05:07.000 +07:00

cli/tests/test_operations.rs

@@ -563,7 +563,7 @@ fn test_op_recover_from_bad_gc() {
     "###);
 
     // "op log" should still be usable.
-    let (stdout, stderr) = test_env.jj_cmd_ok(&repo_path, &["op", "log"]);
+    let (stdout, stderr) = test_env.jj_cmd_ok(&repo_path, &["op", "log", "--ignore-working-copy"]);
     insta::assert_snapshot!(stdout, @r###"
     @  43d51d9b0c0c test-username@host.example.com 2001-02-03 04:05:12.000 +07:00 - 2001-02-03 04:05:12.000 +07:00
     │  describe commit 37bb762e5dc08073ec4323bdffc023a0f0cc901e