fix(formatter): Use `hard_space` between `:` and `TSTypeAnnotation` by leaysgur · Pull Request #20858 · oxc-project/oxc

leaysgur · 2026-03-30T06:32:45Z

Fixes #20519

This ensures that the print_width is calculated correctly in fits().

leaysgur · 2026-03-30T06:32:59Z

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codspeed-hq · 2026-03-30T06:36:29Z

Merging this PR will not alter performance

✅ 44 untouched benchmarks
⏩ 12 skipped benchmarks¹

_{Comparing 03-30-fix_formatter_place_decorator_on_own_line_with_long_property (02ca7b3) with main (c9cd809)}

12 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. ↩

leaysgur · 2026-03-31T01:16:07Z

I noticed something while researching hard_space().

It is almost never actually used
The only difference between Space and HardSpace in fits_element() is whether or not the width is calculated
- Both are discarded when a line break occurs
- I don't know why Space doesn't calculate width in the first place
The issue could also be resolved by changing Space to calculate width just like HardSpace
Incidentally, HardSpace does not exist in the Ruff implementation

Honestly, I can't think of any reason to put trailing spaces at the end of a line...🤔

Dunqing · 2026-03-31T01:51:19Z

I will take a look soon! For HardSpace, you can take a look at #16708 (comment)

Dunqing

LGTM

leaysgur · 2026-04-01T06:25:40Z

@Dunqing How do you think about:

Just remove HardSpace
Calculate fits width for Space

?

Dunqing · 2026-04-02T07:14:53Z

@Dunqing How do you think about:

Just remove HardSpace

Calculate fits width for Space

?

It is indeed a bug; I sent a PR to fix it instead of working around it. #20858

leaysgur · 2026-04-02T08:04:55Z

Closing, at the very least, this PR is useless now.

…d-mode early exit (#20954) Closes #20519 Alternative to #20858 ## Summary The `fits()` measurer in the printer defers `Space` elements via a `pending_space` boolean flag. When the measurer exits early through an expanded-mode line break (`Fits::Yes`), any unresolved `pending_space` is silently lost — causing the measured width to be off by one. This caused the decorator in `@property(...) prop: Type` to incorrectly stay on the same line because the space after `:` was not counted in the width measurement. ### Root cause In `FitsMeasurer::fits_element`, `Space` sets `pending_space = true` (deferred), while `HardSpace` immediately increments `line_width`. When `fits()` returns `Fits::Yes` via the expanded-mode line break path (line 1040), the pending space is never resolved. For the decorator case: 1. After `@property(...)` + space + `tooltipPlacement` + `:` → `line_width = 80` 2. `Space` after `:` → `pending_space = true` (line_width stays 80) 3. Union type group inherits Expanded mode → `if_group_breaks(separator)` included 4. Separator's `SoftOrSpace` in Expanded mode → `return Fits::Yes` **without resolving pending_space** 5. The +1 char from the space is lost, making the decorator group incorrectly "fit" ### Fix Resolve `pending_space` before returning `Fits::Yes` from the expanded-mode early exit path. This matches Ruff's approach where `Space` is counted eagerly via `fits_text(Text::Token(" "))`. ### Conformance - JS: 746/753 (unchanged) - TS: 591/601 (unchanged — `18148.ts` fixed, `comment.ts` regressed) The `comment.ts` regression (`typescript/union/consistent-with-flow/comment.ts`) is a **pre-existing Prettier bug** — at `printWidth: 81`, Prettier itself produces the same double-indented output with a spurious blank line: ```ts // printWidth: 81 → Prettier also double-indents: type SuperLong...Blaa = ← spurious blank line | Fooo1000 ← 4 spaces (double indent) ``` At exactly 80 chars, Prettier avoids this only because its own fits check has the same off-by-one (the space is not counted), causing the Fluid layout's inner group to accidentally "fit". ## Test plan - [x] `cargo test -p oxc_formatter` — 262 passed - [x] `cargo test -p oxc_formatter -- fixtures` — 213 passed (including new `issue-20519.ts`) - [x] `cargo run -p oxc_prettier_conformance` — JS 746/753, TS 591/601 - [x] `cargo clippy -p oxc_formatter` — clean 🤖 Generated with [Claude Code](https://claude.com/claude-code)

github-actions bot added A-formatter Area - Formatter C-bug Category - Bug labels Mar 30, 2026

leaysgur force-pushed the 03-30-fix_formatter_place_decorator_on_own_line_with_long_property branch from 8c3a7c0 to 9d7b6e3 Compare March 30, 2026 06:49

github-actions bot added the A-cli Area - CLI label Mar 30, 2026

leaysgur changed the title ~~fix(formatter): Place decorator on own line with long property~~ fix(formatter): Check pending space width in fits measurement Mar 30, 2026

fix(formatter): Place decorator on own line with long property

02ca7b3

leaysgur force-pushed the 03-30-fix_formatter_place_decorator_on_own_line_with_long_property branch from 9d7b6e3 to 02ca7b3 Compare March 30, 2026 07:04

leaysgur changed the title ~~fix(formatter): Check pending space width in fits measurement~~ fix(formatter): Use hard_space between : and TSTypeAnnotation Mar 30, 2026

leaysgur mentioned this pull request Mar 30, 2026

fix(formatter): Use hard_space for as_or_satisfies #20859

Closed

leaysgur marked this pull request as ready for review March 30, 2026 07:21

leaysgur requested a review from Dunqing as a code owner March 30, 2026 07:21

leaysgur assigned Dunqing Mar 30, 2026

Dunqing approved these changes Apr 1, 2026

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Dunqing mentioned this pull request Apr 2, 2026

fix(formatter): resolve pending space in fits measurer before expanded-mode early exit #20954

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leaysgur closed this Apr 2, 2026

leaysgur deleted the 03-30-fix_formatter_place_decorator_on_own_line_with_long_property branch April 2, 2026 08:05

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fix(formatter): Use `hard_space` between `:` and `TSTypeAnnotation`#20858

fix(formatter): Use `hard_space` between `:` and `TSTypeAnnotation`#20858
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