From f8d325dbfef5fec7ee109e37c624236998de8843 Mon Sep 17 00:00:00 2001
From: JT <547158+jntrnr@users.noreply.github.com>
Date: Thu, 27 Jul 2023 06:22:08 +1200
Subject: [PATCH] Set the rest variable to the correct type (#9816)

# Description

This fixes the type of `$rest` to be a `List<...>` so that it properly
is checked in function bodies.

fixes https://github.com/nushell/nushell/issues/9809
---
 crates/nu-parser/src/parser.rs | 2 +-
 src/tests/test_parser.rs       | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/crates/nu-parser/src/parser.rs b/crates/nu-parser/src/parser.rs
index 1aee66d786..c592b4e479 100644
--- a/crates/nu-parser/src/parser.rs
+++ b/crates/nu-parser/src/parser.rs
@@ -3695,7 +3695,7 @@ pub fn parse_signature_helper(working_set: &mut StateWorkingSet, span: Span) ->
                                     Arg::RestPositional(PositionalArg {
                                         shape, var_id, ..
                                     }) => {
-                                        working_set.set_variable_type(var_id.expect("internal error: all custom parameters must have var_ids"), syntax_shape.to_type());
+                                        working_set.set_variable_type(var_id.expect("internal error: all custom parameters must have var_ids"), Type::List(Box::new(syntax_shape.to_type())));
                                         *shape = syntax_shape;
                                     }
                                     Arg::Flag(Flag { arg, var_id, .. }) => {
diff --git a/src/tests/test_parser.rs b/src/tests/test_parser.rs
index 24ce15b001..7d0b678fd0 100644
--- a/src/tests/test_parser.rs
+++ b/src/tests/test_parser.rs
@@ -665,3 +665,11 @@ fn properly_nest_captures() -> TestResult {
 fn properly_nest_captures_call_first() -> TestResult {
     run_test(r#"do { let b = 3; c; def c [] { $b }; c }"#, "3")
 }
+
+#[test]
+fn properly_typecheck_rest_param() -> TestResult {
+    run_test(
+        r#"def foo [...rest: string] { $rest | length }; foo "a" "b" "c""#,
+        "3",
+    )
+}