do command: Make closure support default parameters and type checking (#12056)

# Description
Fixes: #11287
Fixes: #11318

It's implemented by porting the similar logic in `eval_call`, I've tried
to reduce duplicate code, but it seems that it's hard without using
macros.

3ee2fc60f9/crates/nu-engine/src/eval.rs (L60-L130)

It only works for `do` command.

# User-Facing Changes
## Closure supports optional parameter
```nushell
let code = {|x?| print ($x | default "i'm the default")}
do $code
```
Previously it raises an error, after this change, it prints `i'm the
default`.

## Closure supports type checking
```nushell
let code = {|x: int| echo $x}
do $code "aa"
```
After this change, it will raise an error with a message: `can't convert
string to int`

# Tests + Formatting
Done

# After Submitting
NaN

crates/nu-cmd-lang/src/core_commands/do_.rs

@@ -6,7 +6,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Closure, Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoSpanned, ListStream, PipelineData, RawStream, ShellError, Signature,
-    SyntaxShape, Type, Value,
+    Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -82,44 +82,8 @@ impl Command for Do {
         let mut callee_stack = caller_stack.captures_to_stack(block.captures);
         let block = engine_state.get_block(block.block_id);
 
-        let params: Vec<_> = block
-            .signature
-            .required_positional
-            .iter()
-            .chain(block.signature.optional_positional.iter())
-            .collect();
-
-        for param in params.iter().zip(&rest) {
-            if let Some(var_id) = param.0.var_id {
-                callee_stack.add_var(var_id, param.1.clone())
-            }
-        }
-
-        if let Some(param) = &block.signature.rest_positional {
-            if rest.len() > params.len() {
-                let mut rest_items = vec![];
-
-                for r in rest.into_iter().skip(params.len()) {
-                    rest_items.push(r);
-                }
-
-                let span = if let Some(rest_item) = rest_items.first() {
-                    rest_item.span()
-                } else {
-                    call.head
-                };
-
-                callee_stack.add_var(
-                    param
-                        .var_id
-                        .expect("Internal error: rest positional parameter lacks var_id"),
-                    Value::list(rest_items, span),
-                )
-            }
-        }
-
+        bind_args_to(&mut callee_stack, &block.signature, rest, call.head)?;
         let eval_block_with_early_return = get_eval_block_with_early_return(engine_state);
-
         let result = eval_block_with_early_return(
             engine_state,
             &mut callee_stack,
@@ -324,6 +288,79 @@ impl Command for Do {
     }
 }
 
+fn bind_args_to(
+    stack: &mut Stack,
+    signature: &Signature,
+    args: Vec<Value>,
+    head_span: Span,
+) -> Result<(), ShellError> {
+    let mut val_iter = args.into_iter();
+    for (param, required) in signature
+        .required_positional
+        .iter()
+        .map(|p| (p, true))
+        .chain(signature.optional_positional.iter().map(|p| (p, false)))
+    {
+        let var_id = param
+            .var_id
+            .expect("internal error: all custom parameters must have var_ids");
+        if let Some(result) = val_iter.next() {
+            let param_type = param.shape.to_type();
+            if required && !result.get_type().is_subtype(&param_type) {
+                // need to check if result is an empty list, and param_type is table or list
+                // nushell needs to pass type checking for the case.
+                let empty_list_matches = result
+                    .as_list()
+                    .map(|l| l.is_empty() && matches!(param_type, Type::List(_) | Type::Table(_)))
+                    .unwrap_or(false);
+
+                if !empty_list_matches {
+                    return Err(ShellError::CantConvert {
+                        to_type: param.shape.to_type().to_string(),
+                        from_type: result.get_type().to_string(),
+                        span: result.span(),
+                        help: None,
+                    });
+                }
+            }
+            stack.add_var(var_id, result);
+        } else if let Some(value) = &param.default_value {
+            stack.add_var(var_id, value.to_owned())
+        } else if !required {
+            stack.add_var(var_id, Value::nothing(head_span))
+        } else {
+            return Err(ShellError::MissingParameter {
+                param_name: param.name.to_string(),
+                span: head_span,
+            });
+        }
+    }
+
+    if let Some(rest_positional) = &signature.rest_positional {
+        let mut rest_items = vec![];
+
+        for result in
+            val_iter.skip(signature.required_positional.len() + signature.optional_positional.len())
+        {
+            rest_items.push(result);
+        }
+
+        let span = if let Some(rest_item) = rest_items.first() {
+            rest_item.span()
+        } else {
+            head_span
+        };
+
+        stack.add_var(
+            rest_positional
+                .var_id
+                .expect("Internal error: rest positional parameter lacks var_id"),
+            Value::list(rest_items, span),
+        )
+    }
+    Ok(())
+}
+
 mod test {
     #[test]
     fn test_examples() {

tests/shell/pipeline/commands/internal.rs

@@ -521,6 +521,26 @@ fn run_dynamic_closures() {
     assert_eq!(actual.out, "holaaaa");
 }
 
+#[test]
+fn dynamic_closure_type_check() {
+    let actual = nu!(r#"let closure = {|x: int| echo $x}; do $closure "aa""#);
+    assert!(actual.err.contains("can't convert string to int"))
+}
+
+#[test]
+fn dynamic_closure_optional_arg() {
+    let actual = nu!(r#"let closure = {|x: int = 3| echo $x}; do $closure"#);
+    assert_eq!(actual.out, "3");
+    let actual = nu!(r#"let closure = {|x: int = 3| echo $x}; do $closure 10"#);
+    assert_eq!(actual.out, "10");
+}
+
+#[test]
+fn dynamic_closure_rest_args() {
+    let actual = nu!(r#"let closure = {|...args| $args | str join ""}; do $closure 1 2 3"#);
+    assert_eq!(actual.out, "123");
+}
+
 #[cfg(feature = "which-support")]
 #[test]
 fn argument_subexpression_reports_errors() {