From 1920ece759310ee78e0b1c1c447b8f27adce57b7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Antoine=20B=C3=BCsch?= <antoine.busch@gmail.com>
Date: Sun, 7 Jan 2024 21:51:39 +1100
Subject: [PATCH] fix: closure captures can also be constants (#11493)

<!--
if this PR closes one or more issues, you can automatically link the PR
with
them by using one of the [*linking
keywords*](https://docs.github.com/en/issues/tracking-your-work-with-issues/linking-a-pull-request-to-an-issue#linking-a-pull-request-to-an-issue-using-a-keyword),
e.g.
- this PR should close #xxxx
- fixes #xxxx

you can also mention related issues, PRs or discussions!
-->

# Description
<!--
Thank you for improving Nushell. Please, check our [contributing
guide](../CONTRIBUTING.md) and talk to the core team before making major
changes.

Description of your pull request goes here. **Provide examples and/or
screenshots** if your changes affect the user experience.
-->
When evaluating a closure (in
`EvalRuntime::eval_row_condition_or_closure()`), we try to resolve the
closure's block's captures, but we only check if they're variables on
the stack. We need to also check if they are constants (see the logic in
`Stack::gather_captures()`).

fixes #10701
# User-Facing Changes
<!-- List of all changes that impact the user experience here. This
helps us keep track of breaking changes. -->

# Tests + Formatting
<!--
Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used` to
check that you're using the standard code style
- `cargo test --workspace` to check that all tests pass (on Windows make
sure to [enable developer
mode](https://learn.microsoft.com/en-us/windows/apps/get-started/developer-mode-features-and-debugging))
- `cargo run -- -c "use std testing; testing run-tests --path
crates/nu-std"` to run the tests for the standard library

> **Note**
> from `nushell` you can also use the `toolkit` as follows
> ```bash
> use toolkit.nu # or use an `env_change` hook to activate it
automatically
> toolkit check pr
> ```
-->

# After Submitting
<!-- If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.
-->
---
 crates/nu-engine/src/eval.rs | 13 ++++++++++++-
 tests/const_/mod.rs          | 13 +++++++++++++
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/crates/nu-engine/src/eval.rs b/crates/nu-engine/src/eval.rs
index 550eee6e1a..adfc2a795a 100644
--- a/crates/nu-engine/src/eval.rs
+++ b/crates/nu-engine/src/eval.rs
@@ -1102,7 +1102,18 @@ impl Eval for EvalRuntime {
             .get_block(block_id)
             .captures
             .iter()
-            .map(|&id| stack.get_var(id, span).map(|var| (id, var)))
+            .map(|&id| {
+                stack
+                    .get_var(id, span)
+                    .or_else(|_| {
+                        engine_state
+                            .get_var(id)
+                            .const_val
+                            .clone()
+                            .ok_or(ShellError::VariableNotFoundAtRuntime { span })
+                    })
+                    .map(|var| (id, var))
+            })
             .collect::<Result<_, _>>()?;
 
         Ok(Value::closure(Closure { block_id, captures }, span))
diff --git a/tests/const_/mod.rs b/tests/const_/mod.rs
index 9ef7667bc0..a76c19efdc 100644
--- a/tests/const_/mod.rs
+++ b/tests/const_/mod.rs
@@ -304,6 +304,19 @@ fn const_captures_work() {
     assert_eq!(actual.out, "xy");
 }
 
+#[test]
+fn const_captures_in_closures_work() {
+    let module = "module foo {
+        const a = 'world'
+        export def bar [] {
+            'hello ' + $a
+        }
+    }";
+    let inp = &[module, "use foo", "do { foo bar }"];
+    let actual = nu!(&inp.join("; "));
+    assert_eq!(actual.out, "hello world");
+}
+
 #[ignore = "TODO: Need to fix `overlay hide` to hide the constants brough by `overlay use`"]
 #[test]
 fn complex_const_overlay_use_hide() {