feat(transformer/typescript): debug_assert that enum_eval ran in semantic

[Dunqing]

Closes #21667.

Stacked on #22253 (which lands the prerequisite with_enum_eval(true) calls in cargo allocs and the four transformer benches that this assert would otherwise trip).

Problem

The TS enum lowering reads pre-computed member values from Scoping. Those values are only populated when SemanticBuilder::with_enum_eval(true) is set; without it, every get_enum_member_value call returns None, so string-valued members are treated as opaque expressions and the transform emits incorrect reverse mappings.

Example from #21667:

enum Theme {
  Light = "Light",
  Dark = "Dark",
  Default = Theme.Light,
}

When the transformer runs on a Scoping built without enum_eval, it does not recognise Theme.Light as a string and produces:

Theme[Theme["Default"] = Theme.Light] = "Default";

— i.e. a reverse-mapping assignment for a string member, which is wrong (and runtime-observable).

Fix

Add a debug_assert! at the entry of transform_ts_enum (after the decl.declare early return) verifying that the enum's body scope is registered in Scoping.

The check uses get_enum_body_scopes as the signal: add_enum_body_scope has exactly one caller (evaluate_enum_members), which is gated entirely by enum_eval. No new state on Scoping / EnumData.

The internal Compiler (crates/oxc/src/compiler.rs) and the playground (napi/playground/src/lib.rs) already enable enum_eval. The benches and cargo allocs are fixed in the parent PR. This guard catches the misuse for any other external caller of Transformer::build_with_scoping.

Test plan

• cargo test -p oxc_transformer — new integration tests in tests/integrations/enum_eval.rs cover both the positive case and the #[should_panic] case (debug-only)
• cargo run -p oxc_transform_conformance — no snapshot changes (the conformance runner goes through CompilerInterface, which already enables enum_eval)
• cargo clippy -p oxc_transformer --tests — clean

[Dunqing]

• feat(transformer/typescript): debug_assert that enum_eval ran in semantic #22252 👈 (View in Graphite)
• chore(tasks): enable enum_eval for transformer-fed semantic builders #22253
• main

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[codspeed-hq]

Merging this PR will not alter performance

✅ 44 untouched benchmarks
⏩ 7 skipped benchmarks¹

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_{Comparing fix-transformer-enum-eval-debug-assert (6fc3230) with main (b154559)²}

Footnotes

1. 7 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. ↩

2. No successful run was found on main (6749b02) during the generation of this report, so b154559 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[Dunqing]

Merge activity

• May 10, 9:35 AM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
• May 10, 9:35 AM UTC: Dunqing added this pull request to the Graphite merge queue.
• May 10, 9:39 AM UTC: Merged by the Graphite merge queue.