cli: add ui.allow-filesets to experiment with fileset/pattern syntax

The pattern syntax could be enabled unconditionally, but I want to fully
replace the ad-hoc pattern parsing function.

CHANGELOG.md

@@ -31,7 +31,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * `jj status` now supports filtering by paths. For example, `jj status .` will
   only list changed files that are descendants of the current directory.
 
-* File path arguments now support [file pattern
+* A new config option `ui.allow-filesets` has been added to enable [file pattern
   syntax](docs/filesets.md#file-patterns).
 
 * `jj prev` and `jj next` now work when the working copy revision is a merge.

cli/src/cli_util.rs

@@ -656,7 +656,7 @@ impl WorkspaceCommandHelper {
         // empty arguments.
         if values.is_empty() {
             Ok(FilesetExpression::all())
-        } else {
+        } else if self.settings.config().get_bool("ui.allow-filesets")? {
             let ctx = self.fileset_parse_context();
             let expressions = values
                 .iter()
@@ -665,6 +665,13 @@ impl WorkspaceCommandHelper {
                 .try_collect()
                 .map_err(user_error)?;
             Ok(FilesetExpression::union_all(expressions))
+        } else {
+            let expressions = values
+                .iter()
+                .map(|v| self.parse_file_path(v))
+                .map_ok(FilesetExpression::prefix_path)
+                .try_collect()?;
+            Ok(FilesetExpression::union_all(expressions))
         }
     }
 

cli/src/config-schema.json

@@ -41,6 +41,11 @@
                     "description": "Whether to allow initializing a repo with the native backend",
                     "default": false
                 },
+                "allow-filesets": {
+                    "type": "boolean",
+                    "description": "Whether to parse path arguments as fileset expressions",
+                    "default": false
+                },
                 "always-allow-large-revsets": {
                     "type": "boolean",
                     "description": "Whether to allow large revsets to be used in all commands without the `all:` modifier",

cli/src/config/misc.toml

@@ -9,6 +9,7 @@ unamend = ["unsquash"]
 tree-level-conflicts = true
 
 [ui]
+allow-filesets = false
 always-allow-large-revsets = false
 diff-instructions = true
 paginate = "auto"

cli/tests/test_log_command.rs

@@ -822,6 +822,18 @@ fn test_log_filtered_by_path() {
     A file2
     "###);
 
+    // Fileset/pattern syntax is disabled by default.
+    let stderr = test_env.jj_cmd_failure(
+        test_env.env_root(),
+        &["log", "-R", repo_path.to_str().unwrap(), "root:file1"],
+    );
+    insta::assert_snapshot!(stderr.replace('\\', "/"), @r###"
+    Error: Path "root:file1" is not in the repo "repo"
+    Caused by: Invalid component ".." in repo-relative path "../root:file1"
+    "###);
+
+    test_env.add_config("ui.allow-filesets = true");
+
     // "root:<path>" is resolved relative to the workspace root.
     let stdout = test_env.jj_cmd_success(
         test_env.env_root(),

docs/filesets.md

@@ -5,6 +5,13 @@ Expressions in this language are called "filesets" (the idea comes from
 [Mercurial](https://repo.mercurial-scm.org/hg/help/filesets)). The language
 consists of file patterns, operators, and functions.
 
+**Filesets support is still experimental.** It can be enabled by
+`ui.allow-filesets`.
+
+```toml
+ui.allow-filesets = true
+```
+
 ## File patterns
 
 The following patterns are supported: