fix(transformer): convert enum numbers to strings in template literals

[Copilot]

• Explore repository structure and understand the issue
• Identify the bug in enum.rs (lines 430-434) - missing number-to-string conversion in template literals
• Create test case for enum template literal with numbers
• Fix the bug by converting numbers to strings in template literal evaluation
• Verify the fix with manual testing (regular numbers, mixed types, negative numbers, floats, Infinity, NaN)
• Run unit tests - all passing
• Run code review - reviewed, minor comment about exhaustiveness (already handled)
• Run security check - no issues found
• Update transform conformance snapshots per CI feedback
• Fix template literal quasi bug (use enumerate instead of zip)
• Add test case for trailing quasi edge case
• Task completed

Summary

Fixed a bug where numeric enum values in TypeScript were not converted to strings when used in template literals. The fix converts ConstantValue::Number to strings using to_js_string() method.

Fixed an additional bug where the last quasi (suffix) in template literals was being dropped due to using zip instead of properly iterating over all quasis with conditional expression access.

Updated the transform conformance snapshots to include both test cases.

Security Summary

No security vulnerabilities were found in the changes.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>transformer: computed enum with number in string template is incorrect</issue_title>
<issue_description>playground
Original report: vitejs/rolldown-vite#472

Input

export enum NumberEnum {
  NUM_1 = 1000,
  NUM_2 = 2000,
  NUM_3 = 3000,
  NUM_4 = 4000,
}

export enum ComputedEnum {
  COMPUTED_1 = `${NumberEnum.NUM_1}-${NumberEnum.NUM_2}`,
  COMPUTED_2 = `${NumberEnum.NUM_3}-${NumberEnum.NUM_4}`,
}

console.log(Object.values(ComputedEnum));

Actual

export let NumberEnum = /* @__PURE__ */ function(NumberEnum) {
	NumberEnum[NumberEnum["NUM_1"] = 1e3] = "NUM_1";
	NumberEnum[NumberEnum["NUM_2"] = 2e3] = "NUM_2";
	NumberEnum[NumberEnum["NUM_3"] = 3e3] = "NUM_3";
	NumberEnum[NumberEnum["NUM_4"] = 4e3] = "NUM_4";
	return NumberEnum;
}({});
export let ComputedEnum = /* @__PURE__ */ function(ComputedEnum) {
	ComputedEnum["COMPUTED_1"] = "-";
	ComputedEnum["COMPUTED_2"] = "-";
	return ComputedEnum;
}({});
console.log(Object.values(ComputedEnum));

Expected

export let NumberEnum = /* @__PURE__ */ function(NumberEnum) {
	NumberEnum[NumberEnum["NUM_1"] = 1e3] = "NUM_1";
	NumberEnum[NumberEnum["NUM_2"] = 2e3] = "NUM_2";
	NumberEnum[NumberEnum["NUM_3"] = 3e3] = "NUM_3";
	NumberEnum[NumberEnum["NUM_4"] = 4e3] = "NUM_4";
	return NumberEnum;
}({});
export let ComputedEnum = /* @__PURE__ */ function(ComputedEnum) {
	ComputedEnum["COMPUTED_1"] = "1000-2000";
	ComputedEnum["COMPUTED_2"] = "3000-4000";
	return ComputedEnum;
}({});
console.log(Object.values(ComputedEnum));

</issue_description>

<agent_instructions>We should take a look at ./crates/oxc_transformer/src/typescript/enum.rs to check if there is a bug</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes transformer: computed enum with number in string template is incorrect #15182

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[codspeed-hq]

CodSpeed Performance Report

Merging #15183 will not alter performance

_{Comparing copilot/fix-computed-enum-issue (b4c7d79) with main (ec6721c)}

Summary

✅ 33 untouched
⏩ 4 skipped¹

Footnotes

1. 4 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[Dunqing]

@copilot CI job fails, the reason is that you have to update the coverage snapshots

[Copilot]

@copilot CI job fails, the reason is that you have to update the coverage snapshots

Updated the transform conformance snapshot in commit 6f83696.

[Copilot]

Pull Request Overview

This PR adds support for converting numeric enum values to strings within template literals during TypeScript enum transformation. The key change enables template literals in enum declarations to correctly interpolate numeric enum members (e.g., `${NumberEnum.NUM_1}-${NumberEnum.NUM_2}`).

• Extended enum evaluation to handle ConstantValue::Number in template literals by converting them to strings
• Added test case demonstrating template literals with numeric enum references

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
crates/oxc_transformer/src/typescript/enum.rs	Modified template literal evaluation to handle both string and number constant values by matching on the enum type and converting numbers to JS strings
tasks/transform_conformance/tests/babel-plugin-transform-typescript/test/fixtures/enum-template-literal-number/input.ts	Added test input with numeric enum and computed enum using template literals
tasks/transform_conformance/tests/babel-plugin-transform-typescript/test/fixtures/enum-template-literal-number/output.js	Added expected transformation output
tasks/transform_conformance/snapshots/oxc.snap.md	Updated test pass count and added semantic mismatch details for the new test case

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