From ad125abf6ae620e87985c8f44772a87c7e63a327 Mon Sep 17 00:00:00 2001
From: Ayush Singh <AyushSingh13@users.noreply.github.com>
Date: Sat, 8 Jul 2023 09:48:42 +0100
Subject: [PATCH] fixes `which` showing aliases as built-in nushell commands
 (#9580)
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fixes #8577

# Description
Currently, using `which` on an alias describes it as a nushell built-in
command:
```bash
> alias foo = print "foo!"                                                                                                                                                                                   > which ls foo --all
╭───┬─────┬──────────────────────────┬──────────╮
│ # │ arg │           path           │ built-in │
├───┼─────┼──────────────────────────┼──────────┤
│ 0 │ ls  │ Nushell built-in command │ true     │
│ 1 │ ls  │ /bin/ls                  │ false    │
│ 2 │ foo │ Nushell built-in command │ true     │
╰───┴─────┴──────────────────────────┴──────────╯
```

This PR fixes the behaviour above to the following:
```bash
> alias foo = print "foo!"
> which ls foo --all
╭───┬─────┬──────────────────────────┬──────────╮
│ # │ arg │           path           │ built-in │
├───┼─────┼──────────────────────────┼──────────┤
│ 0 │ ls  │ Nushell built-in command │ true     │
│ 1 │ ls  │ /bin/ls                  │ false    │
│ 2 │ foo │ Nushell alias            │ false    │
╰───┴─────┴──────────────────────────┴──────────╯
```

# User-Facing Changes
Passing in an alias to `which` will no longer return `Nushell built-in
command`, `true` for `path` and `built-in` respectively.

# Tests + Formatting

# After Submitting
---
 crates/nu-command/src/system/which_.rs    |  2 ++
 crates/nu-command/tests/commands/which.rs | 13 +++++++++++++
 2 files changed, 15 insertions(+)

diff --git a/crates/nu-command/src/system/which_.rs b/crates/nu-command/src/system/which_.rs
index 62154cf229..3e89a9896d 100644
--- a/crates/nu-command/src/system/which_.rs
+++ b/crates/nu-command/src/system/which_.rs
@@ -77,6 +77,8 @@ fn get_entry_in_commands(engine_state: &EngineState, name: &str, span: Span) ->
     if let Some(decl_id) = engine_state.find_decl(name.as_bytes(), &[]) {
         let (msg, is_builtin) = if engine_state.get_decl(decl_id).is_custom_command() {
             ("Nushell custom command", false)
+        } else if engine_state.get_decl(decl_id).is_alias() {
+            ("Nushell alias", false)
         } else {
             ("Nushell built-in command", true)
         };
diff --git a/crates/nu-command/tests/commands/which.rs b/crates/nu-command/tests/commands/which.rs
index 75557d9beb..b9f02e8b63 100644
--- a/crates/nu-command/tests/commands/which.rs
+++ b/crates/nu-command/tests/commands/which.rs
@@ -21,6 +21,19 @@ fn which_alias_ls() {
     assert_eq!(actual.out, "Nushell alias: ls -a");
 }
 
+#[test]
+fn which_custom_alias() {
+    let actual = nu!(
+        cwd: ".",
+        r#"alias foo = print "foo!"; which foo | to nuon"#
+    );
+
+    assert_eq!(
+        actual.out,
+        "[[arg, path, built-in]; [foo, \"Nushell alias\", false]]"
+    );
+}
+
 #[test]
 fn which_def_ls() {
     let actual = nu!(