cli: add pointer to the documentation in case of fileset syntax error

CHANGELOG.md

@@ -19,7 +19,6 @@ to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ### Fixed bugs
 
-
 ## [0.22.0] - 2024-10-02
 
 ### Breaking changes

cli/src/command_error.rs

@@ -613,14 +613,17 @@ fn file_pattern_parse_error_hint(err: &FilePatternParseError) -> Option<String>
 
 fn fileset_parse_error_hint(err: &FilesetParseError) -> Option<String> {
     match err.kind() {
+        FilesetParseErrorKind::SyntaxError => Some(String::from(
+            "See https://martinvonz.github.io/jj/latest/filesets/ for filesets syntax, or for how \
+             to match file paths.",
+        )),
         FilesetParseErrorKind::NoSuchFunction {
             name: _,
             candidates,
         } => format_similarity_hint(candidates),
         FilesetParseErrorKind::InvalidArguments { .. } | FilesetParseErrorKind::Expression(_) => {
             find_source_parse_error_hint(&err)
         }
-        _ => None,
     }
 }
 

cli/tests/test_global_opts.rs

@@ -291,6 +291,31 @@ fn test_bad_path() {
     "###);
 }
 
+#[test]
+fn test_invalid_filesets_looking_like_filepaths() {
+    let test_env = TestEnvironment::default();
+    test_env.jj_cmd_ok(test_env.env_root(), &["git", "init", "repo"]);
+    let repo_path = test_env.env_root().join("repo");
+
+    let stderr = test_env.jj_cmd_failure(&repo_path, &["file", "show", "abc~"]);
+    insta::assert_snapshot!(stderr, @r#"
+    Error: Failed to parse fileset: Syntax error
+    Caused by:  --> 1:5
+      |
+    1 | abc~
+      |     ^---
+      |
+      = expected `~` or <primary>
+    Hint: See https://martinvonz.github.io/jj/latest/filesets/ for filesets syntax, or for how to match file paths.
+    "#);
+
+    test_env.add_config(r#"ui.allow-filesets=false"#);
+    let stderr = test_env.jj_cmd_failure(&repo_path, &["file", "show", "abc~"]);
+    insta::assert_snapshot!(stderr, @r#"
+    Error: No such path: abc~
+    "#);
+}
+
 #[test]
 fn test_broken_repo_structure() {
     let test_env = TestEnvironment::default();

cli/tests/test_revset_output.rs

@@ -141,7 +141,7 @@ fn test_bad_function_call() {
     "###);
 
     let stderr = test_env.jj_cmd_failure(&repo_path, &["log", "-r", "files(not::a-fileset)"]);
-    insta::assert_snapshot!(stderr, @r###"
+    insta::assert_snapshot!(stderr, @r#"
     Error: Failed to parse revset: In fileset expression
     Caused by:
     1:  --> 1:7
@@ -156,7 +156,8 @@ fn test_bad_function_call() {
       |     ^---
       |
       = expected <identifier>, <string_literal>, or <raw_string_literal>
-    "###);
+    Hint: See https://martinvonz.github.io/jj/latest/filesets/ for filesets syntax, or for how to match file paths.
+    "#);
 
     let stderr = test_env.jj_cmd_failure(&repo_path, &["log", "-r", r#"files(foo:"bar")"#]);
     insta::assert_snapshot!(stderr, @r###"