fix(turbopack): avoid duplicated .js ext of entry asset

[xusd320]

This pull request updates the logic in the replace_name_placeholder function to improve how file extensions are handled when replacing the [name] placeholder. The new implementation prevents duplicated file extensions in output filenames, addressing cases where the name already contains an extension and the template also appends the same extension.

Filename placeholder handling improvements:

• Updated replace_name_placeholder in chunking_context.rs to strip duplicate extensions from the name when the template text after [name] starts with the same extension, preventing outputs like foo.js.js.

[gemini-code-assist]

Summary of Changes

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This pull request refines the logic for replacing the [name] placeholder in filenames within Turbopack. The primary goal is to ensure that output filenames do not end up with redundant file extensions, thereby improving the consistency and correctness of generated asset names.

Highlights

• Filename Placeholder Handling: Updated the replace_name_placeholder function to prevent duplicated file extensions (e.g., foo.js.js) when the [name] placeholder is replaced and the template already appends the same extension.

Changelog

• turbopack/crates/turbopack-browser/src/chunking_context.rs
  • Modified the replace_name_placeholder function to include logic that checks for and strips duplicate file extensions from the name argument if the template string immediately following the [name] placeholder already contains that extension.

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[gemini-code-assist]

Code Review

This pull request correctly addresses an issue with duplicated file extensions by introducing more sophisticated logic in replace_name_placeholder. The implementation is sound. I've added one suggestion to further optimize the new logic by using Cow<str> to avoid unnecessary string allocations, which is a common pattern for this kind of string manipulation in Rust.

[gemini-code-assist]

For performance, you can avoid allocating a new String in the case where the name doesn't need to be modified. By using std::borrow::Cow<str> as the return type of the closure, you can return a borrowed slice (Cow::Borrowed) when no changes are made, and an owned String (Cow::Owned) only when the extension is stripped. This avoids unnecessary allocations.

Suggested change

	.replace_all(s, |caps: &regex::Captures| {
	let m = caps.get(0).unwrap();
	let after = &s[m.end()..];
	// If the name already ends with an extension (e.g. "foo.js") and the template
	// text right after [name] starts with that same extension (e.g. ".js"), strip
	// the extension from the name to avoid duplication like "foo.js.js".
	if let Some(dot_pos) = name.rfind('.') {
	let ext = &name[dot_pos..]; // e.g. ".js"
	if after.starts_with(ext) {
	return name[..dot_pos].to_string();
	}
	}
	name.to_string()
	})
	.replace_all(s, |caps: &regex::Captures| -> std::borrow::Cow<str> {
	let m = caps.get(0).unwrap();
	let after = &s[m.end()..];
	// If the name already ends with an extension (e.g. "foo.js") and the template
	// text right after [name] starts with that same extension (e.g. ".js"), strip
	// the extension from the name to avoid duplication like "foo.js.js".
	if let Some(dot_pos) = name.rfind('.') {
	let ext = &name[dot_pos..]; // e.g. ".js"
	if after.starts_with(ext) {
	return std::borrow::Cow::Owned(name[..dot_pos].to_string());
	}
	}
	std::borrow::Cow::Borrowed(name)
	})