Fix alias expansion failing when persistent flags precede the alias by mango766 · Pull Request #12909 · gitbutlerapp/gitbutler

mango766 · 2026-03-18T15:58:13Z

Problem

Running but --json st (or any command with root-level flags before an alias) fails with:

Error: "but st" is not a command. Type "but --help" to see all available commands.

This happens because expand_aliases() always inspects args[1] as the potential alias. When persistent flags appear first, args[1] is a flag like --json, and the function short-circuits without ever seeing the actual alias.

Reported in #12697.

Root Cause

In crates/but/src/alias.rs, expand_aliases() hardcodes the alias position at index 1:

let potential_alias = match args[1].to_str() { ... };
if potential_alias.starts_with('-') || is_known_subcommand(potential_alias) {
    return Ok(args);  // <-- bails here when args[1] is "--json"
}

Fix

Introduce find_first_positional() which scans past leading flags and their values to locate the first positional argument. The function knows which root-level flags consume a value (-C, --current-dir, -f, --format) and skips them accordingly. Boolean flags (--json, -t, --status-after) are stepped over one at a time.

The expanded result preserves all surrounding arguments in their original positions:

but --json st → but --json status
but -C /path stf --verbose → but -C /path status --files --verbose

Testing

Added unit tests covering:

Alias after boolean flag (but --json st)
Alias after flag with value (but -C /path stf)
Trailing args preserved after expansion
All-flags-no-positional passthrough

Closes #12697

`but --json st` would fail with "but st is not a command" because `expand_aliases()` always checked `args[1]` for the alias name. When root-level flags like `--json`, `-C <path>`, or `--status-after` appeared before the subcommand, `args[1]` was a flag, and the function bailed out early. Introduce `find_first_positional()` to skip leading flags (and their values) before locating the alias candidate. The expanded result preserves all surrounding arguments in their original positions. Closes gitbutlerapp#12697

vercel · 2026-03-18T15:58:18Z

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Byron

Thanks a lot for contributing!

I think this looks good and solves a real problem, so I'd definitely want to merge this.

@codex review

Byron · 2026-03-18T22:55:28Z

crates/but/src/alias.rs

 }

+/// Known root-level flags that consume the next argument as a value.
+const FLAGS_WITH_VALUE: &[&str] = &["-C", "--current-dir", "-f", "--format"];


This will probably go stale at some point, but then again, it should be rare to change global flags.

Copilot

Pull request overview

Fixes but CLI alias expansion when persistent/root-level flags (e.g. --json, -C <path>, --format <fmt>) appear before an alias, by scanning past leading flags to find the first positional argument to treat as the potential alias (reported in #12697).

Changes:

Add find_first_positional() to locate the first non-flag argument after leading persistent flags (and their values).
Update expand_aliases() to expand aliases at the discovered positional index while preserving surrounding args.
Add unit tests covering alias expansion after boolean flags, flags-with-values, and all-flags passthrough.

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crates/but/src/alias.rs

+    // Find the first positional (non-flag) argument after "but", skipping
+    // leading flags and their values. This is necessary because persistent
+    // flags like `--json` or `-C <path>` may appear before the subcommand.
+    let alias_index = match find_first_positional(&args) {
+        Some(idx) => idx,
+        None => return Ok(args), // All args are flags, nothing to expand
+    };


crates/but/src/alias.rs

+    #[test]
+    fn expand_default_alias_after_boolean_flag() {
+        // `but --json st` should expand to `but --json status`
+        let args = vec![
+            OsString::from("but"),
+            OsString::from("--json"),
+            OsString::from("st"),
+        ];
+        let result = expand_aliases(args).unwrap();
+        assert_eq!(result[0], OsString::from("but"));
+        assert_eq!(result[1], OsString::from("--json"));
+        assert_eq!(result[2], OsString::from("status"));
+    }
+
+    #[test]
+    fn expand_default_alias_after_flag_with_value() {
+        // `but -C /some/path st` should expand to `but -C /some/path status`
+        let args = vec![
+            OsString::from("but"),
+            OsString::from("-C"),
+            OsString::from("/some/path"),
+            OsString::from("stf"),
+        ];
+        let result = expand_aliases(args).unwrap();
+        assert_eq!(result[0], OsString::from("but"));
+        assert_eq!(result[1], OsString::from("-C"));
+        assert_eq!(result[2], OsString::from("/some/path"));
+        assert_eq!(result[3], OsString::from("status"));
+        assert_eq!(result[4], OsString::from("--files"));


crates/but/src/alias.rs

+    fn expand_default_alias_after_flag_with_value() {
+        // `but -C /some/path st` should expand to `but -C /some/path status`
+        let args = vec![
+            OsString::from("but"),
+            OsString::from("-C"),
+            OsString::from("/some/path"),
+            OsString::from("stf"),
+        ];


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chatgpt-codex-connector · 2026-03-18T23:00:42Z

crates/but/src/alias.rs

 }

+/// Known root-level flags that consume the next argument as a value.
+const FLAGS_WITH_VALUE: &[&str] = &["-C", "--current-dir", "-f", "--format"];


Resolve aliases against the -C repository

Adding -C/--current-dir to FLAGS_WITH_VALUE makes but -C repo <alias> enter expand_aliases(), but the lookup still uses gix::discover(".") a few lines below, so it reads but.alias.* from the caller's cwd instead of repo/.git/config. That means repo-local aliases created with but -C repo alias add ... still fail when invoked from outside that repository, which is exactly the flag combination this change is trying to support.

Useful? React with 👍 / 👎.

chatgpt-codex-connector · 2026-03-18T23:00:42Z

crates/but/src/alias.rs

+        if arg == "--" {
+            // Everything after `--` is positional; the next arg (if any) is the candidate.
+            return if i + 1 < args.len() {
+                Some(i + 1)


Stop expanding aliases after --

Treating the first token after -- as an alias candidate changes the meaning of literal positionals. For example, but -- st (or but -C repo -- st) should pass the literal st through to the root positional parser, but this now rewrites it to status whenever the name matches a built-in or configured alias. Because -- is the explicit end-of-options marker, users lose the escape hatch for alias-like paths or selectors.

Useful? React with 👍 / 👎.

Byron · 2026-03-18T23:43:41Z

@mango766 Could you take a look at the bot-comments and at add your own comments to them (while addressing them or not)?
When done, I can swoop in and sign your commit to make the merge, if you didn't do it already by then.
Setting to draft while the review comments are addressed.

Byron requested a review from Copilot March 18, 2026 22:54

Byron approved these changes Mar 18, 2026

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Byron marked this pull request as draft March 18, 2026 23:43

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Fix alias expansion failing when persistent flags precede the alias#12909

Fix alias expansion failing when persistent flags precede the alias#12909
mango766 wants to merge 1 commit intogitbutlerapp:masterfrom
mango766:fix/alias-expansion-with-leading-flags

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mango766 commented Mar 18, 2026

Problem

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Fix

Testing

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