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fix(codegen): print space before const/declare enum modifier#23013

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fix/codegen-enum-leading-space
Jun 6, 2026
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fix(codegen): print space before const/declare enum modifier#23013
graphite-app[bot] merged 1 commit into
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fix/codegen-enum-leading-space

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@Boshen

@Boshen Boshen commented Jun 6, 2026

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What

TSEnumDeclaration::gen printed the declare / const modifiers before its print_space_before_identifier() guard (which sat just before enum). A leading modifier could therefore merge with a preceding identifier-char token.

Most visible when minified, where the soft newline between a do and its body collapses:

do const enum C {} while (0);
  • Before: do const enum C {}while(0);doconst enum C {}while(0);
  • After: do const enum C {}while(0);

The guard is moved to the start of the declaration so it covers the declare/const prefixes.

@github-actions github-actions Bot added the A-codegen Area - Code Generation label Jun 6, 2026
@Boshen Boshen added the 0-merge Merge with Graphite Merge Queue label Jun 6, 2026

Boshen commented Jun 6, 2026

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## What

`TSEnumDeclaration::gen` printed the `declare ` / `const ` modifiers *before* its `print_space_before_identifier()` guard (which sat just before `enum`). A leading modifier could therefore merge with a preceding identifier-char token.

Most visible when minified, where the soft newline between a `do` and its body collapses:

```ts
do const enum C {} while (0);
```

- Before: `do const enum C {}while(0);` → `doconst enum C {}while(0);`
- After: `do const enum C {}while(0);`

The guard is moved to the start of the declaration so it covers the `declare`/`const` prefixes.
@graphite-app graphite-app Bot force-pushed the fix/codegen-enum-leading-space branch from b86954b to 184edef Compare June 6, 2026 13:24
@codspeed-hq

codspeed-hq Bot commented Jun 6, 2026

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Merging this PR will not alter performance

✅ 52 untouched benchmarks
⏩ 14 skipped benchmarks1


Comparing fix/codegen-enum-leading-space (b86954b) with main (597ed85)

Open in CodSpeed

Footnotes

  1. 14 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.

@graphite-app graphite-app Bot merged commit 184edef into main Jun 6, 2026
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@graphite-app graphite-app Bot deleted the fix/codegen-enum-leading-space branch June 6, 2026 13:28
@graphite-app graphite-app Bot removed the 0-merge Merge with Graphite Merge Queue label Jun 6, 2026
graphite-app Bot pushed a commit that referenced this pull request Jun 6, 2026
…ing (#23024)

## What

Found with a self-written whitespace analyzer (for each space in oxc's minified output, remove it and check the result still canonicalizes to the same AST — if so the space was non-optimal). The most common hit:

`ExportDefaultDeclaration` printed `"export default "` with an unconditional trailing space, kept before non-identifier values when minifying:

| Input | Before | After |
| --- | --- | --- |
| `export default {a:1}` | `export default {a:1}` | `export default{a:1}` |
| `export default [1]` | `export default [1]` | `export default[1]` |
| `export default (a,b)` | `export default (a,b)` | `export default(a,b)` |
| `export default "s"` | `export default "s"` | ``export default`s` `` |

## Fix

Use a soft space (kept when pretty-printing) and let the value insert a hard space only before an identifier-like token — matching how `return` already works, and esbuild's `SExportDefault` printer (`print("export default")` + `printSpace()`).

Spaces that are required are preserved: `export default function(){}`, `export default 5`, `export default foo`, `export default class C{}`.

### TypeScript

Exposed a latent bug: `TSInterfaceDeclaration` printed `interface` without a `print_space_before_identifier()` guard, so `export default interface I {}` would have minified to `export defaultinterface`. Added the guard (same fix as #23013 for enums). `export default interface`, `export default abstract class`, and `export default <const>x` all verified to round-trip.

Pretty-print output is unchanged. Codegen (115) and minifier (506) suites pass.
Boshen added a commit that referenced this pull request Jun 8, 2026
### 💥 BREAKING CHANGES

- ee4dc73 ast: [**BREAKING**] Add `#[non_exhaustive]` to AST nodes
(#23046) (overlookmotel)
- 4c35362 ast: [**BREAKING**] Add
`AstBuilder::template_element_escape_raw` and
`template_element_escape_raw_with_lone_surrogates` methods (#23047)
(overlookmotel)

### 🚀 Features

- b846ab2 react_compiler: Integrate the Rust port of the React Compiler
(#22942) (Boshen)
- 5b8dd68 parser: Report TS1255 for invalid class definite assertions
(#22917) (camc314)
- 85efabf semantic: Make building the class table optional, off by
default (#22862) (Boshen)

### 🐛 Bug Fixes

- 556acdc codegen: Parenthesize TS-cast assignment targets (#23112)
(Boshen)
- 37169ff codegen: Don't emit space between postfix `--` and `>` when
minifying (#23036) (Boshen)
- a4b1bf7 codegen: Drop redundant whitespace in minified TypeScript
output (#23038) (Boshen)
- cf53285 parser: Report reserved type-declaration names in the parser
(#23035) (Boshen)
- 4e44969 ast: Fix UB in `escape_template_element_raw` (#23052)
(overlookmotel)
- c543154 parser: Report comma operator in JSX expression in the parser
(#23030) (Boshen)
- 325c94f codegen: Tighten conditional-type and constructor-type
whitespace when minifying (#23033) (Boshen)
- 95dd3a2 parser: Report `import type` alias to a non-external reference
in the parser (#23032) (Boshen)
- 90180b8 codegen: Drop space after `:` in function return type when
minifying (#23028) (Boshen)
- 6da876e parser: Report `abstract` private class field in the parser
(#23029) (Boshen)
- 28467ce codegen: Don't emit space before a postfix update operand when
minifying (#23027) (Boshen)
- cb29926 codegen: Drop redundant space after `export default` when
minifying (#23024) (Boshen)
- 62965ae codegen: Drop redundant space after `else` when minifying
(#23025) (Boshen)
- 989230a parser: Report compound assignment to non-simple target in the
parser (#23022) (Boshen)
- 06f367c parser: Report `super.#field` private access in the parser
(#23014) (Boshen)
- 184edef codegen: Print space before `const`/`declare` enum modifier
(#23013) (Boshen)
- 4d722e0 parser: Report duplicate switch `default` clause in the parser
(#23012) (Boshen)
- 597ed85 codegen: Parenthesize `let`/`async` for-of head target
(#23008) (Boshen)
- 8b631bf codegen: Remove stray space before mapped type value colon
(#23010) (Boshen)
- c08407e codegen: Don't over-parenthesize `in` inside an arrow in a
for-init (#23009) (Boshen)
- 600cd6f codegen: Parenthesize lower-precedence
`TSInstantiationExpression` operand (#23007) (Boshen)
- 187e1a5 codegen: Don't leak space after comment-only JSX expression
container (#23006) (Boshen)
- 294c473 codegen: Don't over-parenthesize `TSTypeAssertion` operand
(#23004) (Boshen)
- 786d96f codegen: Give `TSTypeAssertion` unary precedence (#23002)
(Boshen)
- 1295882 parser: Report `new.target` and `import.meta` syntax errors in
the parser (#23003) (Boshen)
- d727b6b codegen: Parenthesize `await` expression as base of `**`
(#23001) (Boshen)
- 67dfa08 codegen: Keep parentheses around `new` callees containing a
call (#22997) (Boshen)
- 17e7cf3 parser: Disallow unerasable `as`/`satisfies` assertions
(#22986) (Boshen)
- beb46d3 parser: Commit to module goal on decorated exports (#22941)
(Boshen)
- 49e63f7 isolated-declarations: Require annotations for satisfies
initializers (#22898) (camc314)
- 8c93601 isolated-declarations: Allow unknown enum initializer in
non-const enum (#22900) (camc314)

### ⚡ Performance

- 7d89909 parser: Peek instead of lookahead for yield disambiguation
(#23071) (Boshen)
- bf872f0 parser: Skip arrow lookahead for a parenthesized literal
(#23070) (Boshen)
- d19fc54 parser: Guard type-argument speculation behind an angle-token
check (#23069) (Boshen)
- 8eb5507 parser: Skip redundant member-rest re-scan on call entry
(#23068) (Boshen)
- 883dfc1 parser: Skip parse_call_expression_rest when no call follows
(#23063) (Boshen)
- b171153 parser: Peek before the await-using lookahead (#23059)
(Boshen)
- 56f21bd parser: Use peek_token for the TS `asserts` type predicate
(#23058) (Boshen)
- 68805ac parser: Use peek_token instead of checkpoint/rewind for
single-token decisions (#23056) (Boshen)
- 1f9d8eb ast: `AstBuilder::template_element_escape_raw` avoid
allocation if no escape required (#23053) (overlookmotel)
- 502b04d semantic: Move cold function redeclaration handling into
`#[cold]` function (#22973) (overlookmotel)

### 📚 Documentation

- 275d318 napi/minifier: Point `target` to oxc docs (#23102) (camc314)

Co-authored-by: Boshen <1430279+Boshen@users.noreply.github.com>
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