refactor(all): pass `[]` for empty `ArenaVec` args to AST builder methods by overlookmotel · Pull Request #24622 · oxc-project/oxc

overlookmotel · 2026-07-17T12:35:29Z

Pure refactor. Just shorten code.

#24621 made AST builder methods take arrays as params.

Replace ArenaVec::new_in(...) arguments written inline at AST builder method call sites with the empty array literal [].

let block = Statement::new_block_statement(SPAN, ArenaVec::new_in(ctx), ctx);

->

let block = Statement::new_block_statement(SPAN, [], ctx);

overlookmotel · 2026-07-17T12:35:46Z

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codspeed-hq · 2026-07-17T12:44:00Z

Merging this PR will not alter performance

✅ 67 untouched benchmarks
⏩ 9 skipped benchmarks¹

_{Comparing om/07-17-refactor_all_pass_for_empty_arenavec_args_to_ast_builder_methods (c1a074c) with main (2338c13)²}

9 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. ↩
No successful run was found on main (c1a074c) during the generation of this report, so 2338c13 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

Copilot

Pull request overview

Refactors call sites across the codebase to use the new AST builder ergonomics introduced in #24621 by passing [] for empty ArenaVec parameters, reducing boilerplate without changing behavior.

Changes:

Replaces inline ArenaVec::new_in(...) empty arguments with [] for AST builder methods that now accept arrays via IntoIn.
Applies the same mechanical shortening in parser, transformer, minifier, isolated declarations, codegen tests, and React compiler code.
Cleans up an unused ArenaVec import where it became unnecessary.

Reviewed changes

Copilot reviewed 37 out of 37 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
crates/oxc_transformer/src/utils/ast_builder.rs	Use `[]` for empty params/args/directives when building AST nodes.
crates/oxc_transformer/src/typescript/namespace.rs	Use `[]` for empty object literal properties.
crates/oxc_transformer/src/typescript/enum.rs	Use `[]` for empty decorators/properties/args in enum transform output.
crates/oxc_transformer/src/typescript/class.rs	Use `[]` for empty decorators on generated class elements.
crates/oxc_transformer/src/typescript/annotations.rs	Use `[]` for empty export specifiers and empty block statements.
crates/oxc_transformer/src/plugins/styled_components.rs	Update test helper call to pass `[]` for empty vec arg.
crates/oxc_transformer/src/jsx/refresh.rs	Use `[]` for placeholder/empty vecs in generated refresh AST.
crates/oxc_transformer/src/es2026/explicit_resource_management.rs	Use `[]` for empty call arguments in generated code.
crates/oxc_transformer/src/es2022/class_static_block.rs	Use `[]` for empty decorators and drop unused `ArenaVec` import.
crates/oxc_transformer/src/es2022/class_properties/constructor.rs	Use `[]` for empty params/decorators/directives in generated functions.
crates/oxc_transformer/src/es2022/class_properties/class.rs	Use `[]` for empty `new` expression argument lists.
crates/oxc_transformer/src/es2020/nullish_coalescing_operator.rs	Use `[]` for empty decorators and empty call args.
crates/oxc_transformer/src/es2018/object_rest_spread.rs	Use `[]` for empty object props, binding patterns, and template expressions.
crates/oxc_transformer/src/es2018/async_generator_functions/for_await.rs	Use `[]` for empty call arguments.
crates/oxc_transformer/src/es2017/async_to_generator.rs	Use `[]` for empty directives/call args in wrapper function generation.
crates/oxc_transformer/src/decorator/legacy/mod.rs	Use `[]` for empty decorators/template literal expressions.
crates/oxc_transformer/src/common/duplicate.rs	Use `[]` for empty template literal expressions vec.
crates/oxc_transformer/src/common/arrow_function_converter.rs	Use `[]` for empty decorators and function body directives.
crates/oxc_transformer_plugins/src/module_runner_transform.rs	Use `[]` for empty params and empty directives in generated function.
crates/oxc_react_compiler/src/react_compiler/entrypoint/program.rs	Use `[]` for empty export specifiers / call args.
crates/oxc_react_compiler/src/react_compiler_reactive_scopes/codegen_reactive_function.rs	Use `[]` for empty decorators/rest metadata/call args/directives.
crates/oxc_parser/src/lib.rs	Pass `[]` for program comments placeholder (still populated later).
crates/oxc_parser/src/js/module.rs	Use `[]` for empty export specifiers.
crates/oxc_parser/src/js/arrow.rs	Use `[]` for empty arrow function body directives.
crates/oxc_minifier/tests/ecmascript/to_string.rs	Use `[]` for empty object literal properties in tests.
crates/oxc_minifier/tests/ecmascript/to_number.rs	Use `[]` for empty object literal properties in tests.
crates/oxc_minifier/tests/ecmascript/array_join.rs	Use `[]` for empty object literal properties in tests.
crates/oxc_minifier/src/peephole/substitute_alternate_syntax.rs	Use `[]` for empty object/array literal elements in substitutions.
crates/oxc_minifier/src/peephole/remove_dead_code.rs	Use `[]` for empty block statement body.
crates/oxc_isolated_declarations/src/module.rs	Use `[]` for empty export specifiers.
crates/oxc_isolated_declarations/src/lib.rs	Use `[]` for empty directives/specifiers when building new programs/exports.
crates/oxc_isolated_declarations/src/function.rs	Use `[]` for empty parameter decorators.
crates/oxc_isolated_declarations/src/declaration.rs	Use `[]` for empty TS module block body metadata vec.
crates/oxc_isolated_declarations/src/class.rs	Use `[]` for empty decorators and empty signature params decorators.
crates/oxc_codegen/tests/integration/js.rs	Use `[]` for empty template expressions and empty program comments/directives.
crates/oxc_ast/src/builder/custom.rs	Use `[]` for empty decorators/specifiers in custom builder helpers.
crates/oxc_ast_visit/src/utf8_to_utf16/mod.rs	Use `[]` for empty directives in test program construction.

overlookmotel · 2026-07-17T13:37:25Z

@camc314 @Dunqing I'm going to merge this stack without review as I think it's uncontroversial and it touches a lot of files, so I want to get it in before it accrues merge conflicts.

Just tagging you both so you're aware we can now use this shorter syntax when the ArenaVec is being passed to an AST builder method:

ArenaVec::new_in(self) -> []
ArenaVec::from_value_in(x, self) -> [x]
ArenaVec::from_array_in([x, y, z], self) -> [x, y, z]

camc314

nice!

graphite-app · 2026-07-17T13:49:01Z

Merge activity

Jul 17, 1:49 PM UTC: overlookmotel added this pull request to the Graphite merge queue.
Jul 17, 1:58 PM UTC: Merged by the Graphite merge queue.

…hods (#24622) Pure refactor. Just shorten code. #24621 made AST builder methods take arrays as params. Replace `ArenaVec::new_in(...)` arguments written inline at AST builder method call sites with the empty array literal `[]`. ```rs let block = Statement::new_block_statement(SPAN, ArenaVec::new_in(ctx), ctx); ``` \-> ```rs let block = Statement::new_block_statement(SPAN, [], ctx); ```

…#24621) Builds on #24620. Make generated and hand-written AST builder methods take `impl IntoIn<'a, ArenaVec<'a, T>>` instead of `ArenaVec<'a, T>` for their `Vec` params, so callers can pass an array literal (e.g. `[]` or `[a, b]`) in place of building an `ArenaVec` explicitly. This enables shortening code in a lot of places - #24622 and following PRs.

github-actions Bot added A-parser Area - Parser A-minifier Area - Minifier A-ast Area - AST A-transformer Area - Transformer / Transpiler A-codegen Area - Code Generation A-isolated-declarations Isolated Declarations labels Jul 17, 2026

overlookmotel force-pushed the om/07-17-refactor_all_pass_for_empty_arenavec_args_to_ast_builder_methods branch from 60d1e75 to 25e0cac Compare July 17, 2026 13:08

overlookmotel force-pushed the om/07-17-feat_ast_accept_arrays_for_arenavec_params_of_ast_builder_methods branch from 2d01371 to 25a9811 Compare July 17, 2026 13:08

overlookmotel mentioned this pull request Jul 17, 2026

fix(allocator): Vec::from_array_in do not allocate zero-length array #24628

Merged

overlookmotel marked this pull request as ready for review July 17, 2026 13:17

overlookmotel requested a review from Dunqing as a code owner July 17, 2026 13:17

Copilot AI review requested due to automatic review settings July 17, 2026 13:17

Copilot started reviewing on behalf of overlookmotel July 17, 2026 13:18 View session

Copilot AI reviewed Jul 17, 2026

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overlookmotel self-assigned this Jul 17, 2026

This was referenced Jul 17, 2026

feat(ast): allow NONE to be passed to AST builder methods where Option<ArenaVec> is expected #24629

Merged

refactor(react_compiler): shorten code by using NONE #24630

Merged

camc314 approved these changes Jul 17, 2026

View reviewed changes

graphite-app Bot force-pushed the om/07-17-feat_ast_accept_arrays_for_arenavec_params_of_ast_builder_methods branch from 25a9811 to 77230c5 Compare July 17, 2026 13:50

graphite-app Bot force-pushed the om/07-17-refactor_all_pass_for_empty_arenavec_args_to_ast_builder_methods branch from 25e0cac to c1a074c Compare July 17, 2026 13:51

Base automatically changed from om/07-17-feat_ast_accept_arrays_for_arenavec_params_of_ast_builder_methods to main July 17, 2026 13:57

graphite-app Bot merged commit c1a074c into main Jul 17, 2026
41 checks passed

graphite-app Bot deleted the om/07-17-refactor_all_pass_for_empty_arenavec_args_to_ast_builder_methods branch July 17, 2026 13:58

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refactor(all): pass `[]` for empty `ArenaVec` args to AST builder methods#24622

refactor(all): pass `[]` for empty `ArenaVec` args to AST builder methods#24622
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