ensure that when nu evaluates files, it allows early returns (#7415)

# Description

Fixes #7301.

# User-Facing Changes

`return` can now be used in scripts without explicit `def main`.

# Tests + Formatting

Don't forget to add tests that cover your changes. (I'm not sure how to
test this.)

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 -A
clippy::needless_collect` to check that you're using the standard code
style
- `cargo test --workspace` to check that all tests pass

# 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-cli/src/config_files.rs

@@ -41,6 +41,7 @@ pub fn read_plugin_file(
                 &contents,
                 &plugin_filename,
                 PipelineData::empty(),
+                false,
             );
         }
     }
@@ -93,6 +94,7 @@ pub fn eval_config_contents(
                 &contents,
                 &config_filename,
                 PipelineData::empty(),
+                false,
             );
 
             // Merge the environment in case env vars changed in the config

crates/nu-cli/src/eval_file.rs

@@ -106,13 +106,21 @@ pub fn evaluate_file(
             &file,
             file_path_str,
             PipelineData::empty(),
+            true,
         ) {
             std::process::exit(1);
         }
-        if !eval_source(engine_state, stack, args.as_bytes(), "<commandline>", input) {
+        if !eval_source(
+            engine_state,
+            stack,
+            args.as_bytes(),
+            "<commandline>",
+            input,
+            true,
+        ) {
             std::process::exit(1);
         }
-    } else if !eval_source(engine_state, stack, &file, file_path_str, input) {
+    } else if !eval_source(engine_state, stack, &file, file_path_str, input, true) {
         std::process::exit(1);
     }
 

crates/nu-cli/src/repl.rs

@@ -145,6 +145,7 @@ pub fn evaluate_repl(
             s.item.as_bytes(),
             &format!("entry #{entry_num}"),
             PipelineData::empty(),
+            false,
         );
         engine_state.merge_env(stack, get_guaranteed_cwd(engine_state, stack))?;
     }
@@ -472,6 +473,7 @@ pub fn evaluate_repl(
                         s.as_bytes(),
                         &format!("entry #{entry_num}"),
                         PipelineData::empty(),
+                        false,
                     );
                 }
                 let cmd_duration = start_time.elapsed();

crates/nu-cli/src/util.rs

@@ -1,5 +1,5 @@
 use crate::repl::eval_hook;
-use nu_engine::eval_block;
+use nu_engine::{eval_block, eval_block_with_early_return};
 use nu_parser::{escape_quote_string, lex, parse, unescape_unquote_string, Token, TokenContents};
 use nu_protocol::engine::StateWorkingSet;
 use nu_protocol::CliError;
@@ -203,6 +203,7 @@ pub fn eval_source(
     source: &[u8],
     fname: &str,
     input: PipelineData,
+    allow_return: bool,
 ) -> bool {
     let start_time = std::time::Instant::now();
 
@@ -230,7 +231,13 @@ pub fn eval_source(
         return false;
     }
 
-    match eval_block(engine_state, stack, &block, input, false, false) {
+    let b = if allow_return {
+        eval_block_with_early_return(engine_state, stack, &block, input, false, false)
+    } else {
+        eval_block(engine_state, stack, &block, input, false, false)
+    };
+
+    match b {
         Ok(pipeline_data) => {
             let config = engine_state.get_config();
             let result;