Clarify barrel loader export map comment

[2wndrhs]

What?

Clarifies the export map terminology in next-barrel-loader.

The current comment describes the export map format as:

[\"<imported identifier>\", \"<import path>\", \"<exported name>\"]

But for a barrel re-export such as:

export { a as b } from './module-a'

the generated map entry is:

[\"b\", \"./module-a\", \"a\"]

Here, b is the name exported by the barrel file, while a is the original export name from the source module.

Why?

The current wording is ambiguous because the first tuple element is not the source module's original export name. It is the name exported by the barrel file and requested by the user import.

How?

Updates the comment to describe the tuple as:

[\"<barrel export name>\", \"<source module path>\", \"<source export name>\"]

No runtime behavior changes.

Verification

• cargo test -p next-custom-transforms --test fixture optimize_barrel
• git diff --check