refactor(ast_tools): simplify struct field reordering

[overlookmotel]

Follow-on after #20584. Simplify implementation of struct field ordering in ast_tools. This change does not alter any layouts, just shortens the code by taking a simpler approach to handling ZST fields.

[overlookmotel]

• refactor(ast_tools): simplify struct field reordering #20587 👈 (View in Graphite)
• perf(ast): mark AstKind::address as #[inline] #20586
• perf(ast): mark AstKind::span as #[inline] #20585
• perf(ast): place NodeId field after Span in structs #20584
• refactor(ast): re-order layout assertions in memory order #20583
• refactor(ast_tools): convert layout calculation to a struct with methods #20582
• fix(ast_tools): remove NonMax32 primitive #20581
• fix(ast_tools): correctly parse define_index_type! macros #20580
• perf(ast_tools): reduce data passing between functions #20579
• perf(ast_tools): parse files in parallel #20578
• refactor(ast_tools): search all crates which depend on oxc_ast_macros #20577
• main

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[codspeed-hq]

Merging this PR will not alter performance

✅ 53 untouched benchmarks
⏩ 3 skipped benchmarks¹

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_{Comparing om/02-15-refactor_ast_tools_simplify_struct_field_reordering (3a94ef2) with om/02-15-perf_ast_mark_astkind_address_as_inline_ (79deba6)}

Footnotes

1. 3 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. ↩

[Copilot]

Pull request overview

Refactors ast_tools’ struct field reordering logic by explicitly tracking field layout order (including ZSTs), simplifying how layout assertions and #[ast] field-reorder metadata are derived without changing computed sizes/alignments.

Changes:

• Add layout_index to Offset to represent deterministic memory layout order even when ZST offsets collide.
• Simplify struct layout calculation by removing the “collect ZSTs then append last” path and assigning layout order during field placement.
• Update struct-details generation and assertions to sort/emit by layout_index (reflected in regenerated STRUCTS, e.g. Span).

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 1 comment.

File	Description
tasks/ast_tools/src/schema/extensions/layout.rs	Extends Offset with layout_index to disambiguate layout ordering when offsets aren’t unique.
tasks/ast_tools/src/generators/assert_layouts.rs	Assigns layout_index during layout calculation; uses it for assertion ordering and StructDetails emission.
crates/oxc_ast_macros/src/generated/structs.rs	Regenerated struct reorder table based on the updated layout-ordering logic.

[overlookmotel]

Merge activity

• Mar 20, 10:15 PM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
• Mar 20, 10:15 PM UTC: overlookmotel added this pull request to the Graphite merge queue.
• Mar 20, 10:32 PM UTC: Merged by the Graphite merge queue.