git clone: Add depth argument

CHANGELOG.md

@@ -59,6 +59,9 @@ to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 * Initial support for shallow git repositories has been implemented. However
   deepening the history of a shallow repository is not yet supported.
 
+* `jj git clone` now accepts a `--depth <DEPTH>` option, which
+  allows to clone the repository with a given depth.
+
 ### Fixed bugs
 
  * Fixed panic when parsing invalid conflict markers of a particular form.

cli/src/commands/git/clone.rs

@@ -15,6 +15,7 @@
 use std::fs;
 use std::io;
 use std::io::Write;
+use std::num::NonZeroU32;
 use std::path::Path;
 use std::path::PathBuf;
 
@@ -60,6 +61,11 @@ pub struct GitCloneArgs {
     /// Whether or not to colocate the Jujutsu repo with the git repo
     #[arg(long)]
     colocate: bool,
+    /// Create a shallow clone of the given depth
+    // We accept a depth of 0 for parity with git's --depth option.
+    // The option is here to not render a default = 0 in the help message.
+    #[arg(long)]
+    depth: Option<u32>,
 }
 
 fn absolute_git_source(cwd: &Path, source: &str) -> String {
@@ -132,6 +138,7 @@ pub fn cmd_git_clone(
         ui,
         command,
         args.colocate,
+        args.depth.and_then(NonZeroU32::new),
         remote_name,
         &source,
         &canonical_wc_path,
@@ -195,6 +202,7 @@ fn do_git_clone(
     ui: &mut Ui,
     command: &CommandHelper,
     colocate: bool,
+    depth: Option<NonZeroU32>,
     remote_name: &str,
     source: &str,
     wc_path: &Path,
@@ -219,7 +227,7 @@ fn do_git_clone(
         git::fetch(
             fetch_tx.repo_mut(),
             &git_repo,
-            None,
+            depth,
             remote_name,
             &[StringPattern::everything()],
             cb,

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

@@ -961,6 +961,7 @@ The Git repo will be a bare git repo stored inside the `.jj/` directory.
 
   Default value: `origin`
 * `--colocate` — Whether or not to colocate the Jujutsu repo with the git repo
+* `--depth <DEPTH>` — Create a shallow clone of the given depth