Fix duplicate JSDoc @typedef and @callback comments in declaration emit

[heathdutton]

Fixes #62453.

When emitting declaration files from JavaScript with JSDoc @typedef and @callback tags, the comments were being emitted twice: once as converted TypeScript type declarations (correct) and once as raw JSDoc comments (duplicate).

The fix skips emitting @typedef and @callback comments during declaration emit since they are already represented as type declarations.

[Copilot]

Pull request overview

This PR fixes a bug where JSDoc @typedef and @callback comments were being duplicated in TypeScript declaration files. The comments were appearing both as converted TypeScript type declarations (correct) and as the original JSDoc comments (duplicate).

Changes:

• Modified the shouldWriteComment function in the emitter to detect and skip @typedef and @callback comments during declaration emit
• Updated baseline test files to reflect the removal of duplicate JSDoc comments

Reviewed changes

Copilot reviewed 23 out of 23 changed files in this pull request and generated 2 comments.

File	Description
src/compiler/emitter.ts	Added logic to filter out @typedef and @callback comments when emitting declarations
tests/baselines/reference/*.js	Updated baseline expectations to reflect removal of duplicate JSDoc comments in declaration files

[Copilot]

The string matching for '@typedef' and '@callback' could produce false positives if these strings appear in comment content that isn't actually a typedef or callback declaration (e.g., in documentation text or code examples). Consider using a more precise pattern match that checks for these tags at word boundaries, such as matching /@typedef\b/ and /@callback\b/ to ensure they are actual JSDoc tags.

Suggested change

	if (commentText.includes("@typedef") || commentText.includes("@callback")) {
	if (/@typedef\b/.test(commentText) || /@callback\b/.test(commentText)) {

[Copilot]

Creating a substring via slice() for every comment during emit could impact performance when processing files with many comments. Consider checking for the presence of '@typedef' or '@callback' using indexOf() with boundary checks on the original string instead of creating a new substring.

Suggested change

	const commentText = text.slice(pos, end);
	if (commentText.includes("@typedef") || commentText.includes("@callback")) {
	return false;
	}
	const typedefIndex = text.indexOf("@typedef", pos);
	if (typedefIndex !== -1 && typedefIndex < end) {
	return false;
	}
	const callbackIndex = text.indexOf("@callback", pos);
	if (callbackIndex !== -1 && callbackIndex < end) {
	return false;
	}

[heathdutton]

Both suggestions would deviate from existing codebase conventions, but happy to make a change if a human replies.

[typescript-bot]

With 6.0 out as the final release vehicle for this codebase, we're closing all PRs that don't fit the merge criteria for post-6.0 patches. If you think this was a mistake and this PR fits the post-6.0 patch criteria, please post to the 6.0 iteration issue with details (specifically, which PR and which patch criteria it satisfies).

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