config: Respect shell quotations in split_name_and_args

CHANGELOG.md

@@ -79,6 +79,8 @@ to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
   is set in `.gitconfig` (but jj still isn't able to fetch the submodules
   or to operate on them).
 
+* Setting the editor via `ui.editor`, `$EDITOR`, or `JJ_EDITOR` now respects shell quoting.
+
 ## [0.33.0] - 2025-09-03
 
 ### Release highlights

Cargo.toml

@@ -94,6 +94,7 @@ sapling-streampager = "0.11.0"
 scm-record = "0.8.0"
 serde = { version = "1.0", features = ["derive", "rc"] }
 serde_json = "1.0.145"
+shlex = "1.3.0"
 slab = "0.4.11"
 smallvec = { version = "1.15.1", features = [
     "const_generics",

cli/Cargo.toml

@@ -90,6 +90,7 @@ sapling-streampager = { workspace = true }
 scm-record = { workspace = true }
 serde = { workspace = true }
 serde_json = { workspace = true }
+shlex = { workspace = true }
 slab = { workspace = true }
 strsim = { workspace = true }
 tempfile = { workspace = true }

cli/src/config.rs

@@ -825,9 +825,17 @@ impl CommandNameAndArgs {
     pub fn split_name_and_args(&self) -> (Cow<'_, str>, Cow<'_, [String]>) {
         match self {
             Self::String(s) => {
-                // Handle things like `EDITOR=emacs -nw` (TODO: parse shell escapes)
-                let mut args = s.split(' ').map(|s| s.to_owned());
-                (args.next().unwrap().into(), args.collect())
+                let mut parts = shlex::Shlex::new(s);
+                let res = (
+                    parts.next().unwrap_or_default().into(),
+                    parts.by_ref().collect(),
+                );
+                if parts.had_error {
+                    let mut args = s.split(' ').map(|s| s.to_owned());
+                    (args.next().unwrap_or_default().into(), args.collect())
+                } else {
+                    res
+                }
             }
             Self::Vec(NonEmptyCommandArgsVec(a)) => (Cow::Borrowed(&a[0]), Cow::Borrowed(&a[1..])),
             Self::Structured {
@@ -1055,6 +1063,7 @@ mod tests {
                     empty_string = ''
                     array = ['emacs', '-nw']
                     string = 'emacs -nw'
+                    string_quoted = '\"spaced path/to/emacs\" -nw'
                     structured.env = { KEY1 = 'value1', KEY2 = 'value2' }
                     structured.command = ['emacs', '-nw']
                 "},
@@ -1090,6 +1099,15 @@ mod tests {
         assert_eq!(name, "emacs");
         assert_eq!(args, ["-nw"].as_ref());
 
+        let command_args: CommandNameAndArgs = config.get("string_quoted").unwrap();
+        assert_eq!(
+            command_args,
+            CommandNameAndArgs::String("\"spaced path/to/emacs\" -nw".to_owned())
+        );
+        let (name, args) = command_args.split_name_and_args();
+        assert_eq!(name, "spaced path/to/emacs");
+        assert_eq!(args, ["-nw"].as_ref());
+
         let command_args: CommandNameAndArgs = config.get("structured").unwrap();
         assert_eq!(
             command_args,

cli/tests/common/mod.rs

@@ -30,7 +30,10 @@ pub fn fake_bisector_path() -> String {
 pub fn fake_editor_path() -> String {
     let path = assert_cmd::cargo::cargo_bin("fake-editor");
     assert!(path.is_file());
-    path.into_os_string().into_string().unwrap()
+    path.into_os_string()
+        .into_string()
+        .unwrap()
+        .replace("\\", "\\\\")
 }
 
 pub fn fake_diff_editor_path() -> String {