[source_span] Fix CR/CRLF highlighting, point-span context, and subspan by kevmoo · Pull Request #2634 · dart-lang/tools

kevmoo · 2026-10-03T16:53:29Z

Normalize bare \r and \r\n line endings in Highlighter, findLineStart, and subspanLocations (preventing a RangeError when highlighting spans ending at a bare \r, disambiguating multi-line SourceSpanWithContext subspans via span location metadata, and fixing subspan(span.length) on spans ending with the \r of a \r\n sequence).
Fix FileSpan.context returning '' for point spans at column 0 of the last line in a multi-line file without a trailing newline.
Fix _Highlight._normalizeEndOfLine column calculation when start.column > 0 and simplify _Highlight._lastLineLength to fix off-by-one column calculation on plain spans ending with \n\n.
Align _FileSpan.== and _FileSpan.hashCode with SourceSpan without allocating FileLocations, and remove unreachable code in SourceFile.getLine, _FileSpan.subspan, SourceLocation, _Highlight._normalizeTrailingNewline, and subspanLocations.

* Normalize bare `\r` and `\r\n` line endings in `Highlighter`, `findLineStart`, and `subspanLocations` (fixes `SPAN-1` `RangeError` and `subspan` at end of spans ending with `\r` of `\r\n`). * Fix `FileSpan.context` returning `''` for point spans at column 0 of the last line in a multi-line file without a trailing newline (`SPAN-2`). * Fix `_Highlight._normalizeEndOfLine` column calculation when `start.column > 0` and simplify `_Highlight._lastLineLength` to fix off-by-one on plain spans ending with `\n\n`. * Remove unreachable code in `SourceFile.getLine`, `_FileSpan.subspan`, `SourceLocation`, `_Highlight._normalizeTrailingNewline`, and `subspanLocations`, and avoid allocating `FileLocation`s in `_FileSpan.==`.

github-actions · 2026-10-03T16:55:11Z

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Coverage

⚠️

File	Coverage
pkgs/source_span/lib/src/file.dart	💚 91 % ⬆️ 3 %
pkgs/source_span/lib/src/highlighter.dart	💚 97 % ⬆️ 1 %
pkgs/source_span/lib/src/location.dart	💚 97 %
pkgs/source_span/lib/src/span_with_context.dart	💔 91 % ⬇️ 9 %
pkgs/source_span/lib/src/utils.dart	💚 99 % ⬆️ 2 %

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// Copyright (c) 2026, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

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pkgs/html/test/differential_test.dart
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source_span	None	1.10.2	1.10.3-wip	1.10.3-wip	✔️

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Code Review

This pull request addresses several bugs in the source_span package, particularly fixing RangeError and assertion failures when highlighting or slicing spans with bare \r or \r\n line endings, and resolving an issue where FileSpan.context returned an empty string for point spans at the start of the last line in files without trailing newlines. The changes refactor newline detection and normalization across file.dart, highlighter.dart, and utils.dart, and add corresponding tests. The review feedback highlights a critical issue in the updated == operator for _FileSpan, which omits the text comparison when compared to a SourceSpan, potentially leading to asymmetric equality behavior.

… equality tests

davidmorgan

Thanks for this: the CR handling is a big improvement. I fuzzed every string of up to 5 characters over a, b, \r and \n, and every span in each, as a file span, a span with context and a plain span. highlight(), context and subspan go from 2078 throws and 2247 wrong subspan locations on main to none on this PR. With bare CRs, the highlight output is the same as for the file with LF endings.

Two regressions turn up when you highlight a SourceSpanWithContext subspan that keeps its parent's multi-line context. Both are in the inline comments:

SourceSpanWithContext ctx(String s) {
  final f = SourceFile.fromString(s).span(0, s.length);
  return SourceSpanWithContext(f.start, f.end, f.text, f.context);
}
ctx('ab\r\nabba').subspan(3, 3).highlight(); // main: line 1, caret at col 3. PR: labels `0 | ab`, caret on `abba`.
ctx('a\rb\r\n').subspan(3, 4).highlight();   // main: no throw. PR: RangeError (end).

This existing bug isn't caused by the PR, but it is nearby: ctx('b\r\nb\r').subspan(4, 5).highlight() throws on main as well, and on this PR with a different message.

Also existing: a _FileSpan and a SourceSpan with the same offsets and URL compare equal but have different hashCodes, because one hashes (_start, _end, sourceUrl) and the other the two SourceLocations. The new symmetric-equality test pins that equality without checking hashCode.

…n.hashCode * Restore `findLineStart` empty-text CRLF matching on the line containing `\r\n`. * Add `findSpanLineStart` to locate `SourceSpanWithContext` spans once using end-location and start-line/offset metadata, storing `linesBeforeSpan` on `_Highlight` and preserving trailing empty lines for point spans. * Align `_FileSpan.hashCode` with `SourceSpanMixin.hashCode` (`Object.hash(start, end)`) when comparing equal. * Add explicit `line`/`column` subspan assertions, 4-char `SourceSpanWithContext` subspan highlight fuzz tests, and clean up internal tracker labels in `highlight_test.dart`.

kevmoo · 2026-10-22T15:53:10Z

Thanks for the fuzzing sweep! Addressed all inline comments plus the b\r\nb\r subspan case and _FileSpan.hashCode parity in e0926f8 — PTAL.

…LineCandidate

kevmoo · 2026-10-23T17:14:58Z

Addressed both comments: stripped CR from effectiveLineEnd and removed absolute offset checks entirely (which fixes the heuristic while making the flawed tests obsolete, so they are skipped/removed). PTAL.

…ontext * Add an internal `SubspanWithContext` subclass in `lib/src/utils.dart` so `SourceSpanWithContextExtension.subspan` preserves the exact code-unit start offset within `context` without `Expando` state or heuristic line scoring. * Resolve `SubspanWithContext` line starts directly in `findSpanLineStart` and match `SourceSpanWithContext` candidates by column, text, and end location. * Enable all tests in `test/utils_test.dart` and `test/highlight_test.dart` and add multi-line duplicate-line, CRLF, and exhaustive 4-char CR/LF subspan coverage.

* Delegate the non-`SubspanWithContext` fallback in `findSpanLineStart` to `findLineStart` and remove the redundant `_matchesEndLocation` line scan. * Reuse `_isLineEnd` in `subspanLocations` to avoid duplicating CR/LF line-end checks.

@example

…est, tools, webkit_inspection_protocol Revisions updated by `dart tools/rev_sdk_deps.dart`. core (https://github.com/dart-lang/core/compare/04da676..d7bd45c): d7bd45c1 Wed Oct 28 13:23:54 2026 +0530 Chandra ObulaReddy [args] Wrap separators to usageLineLength (dart-lang/core#1032) 6903c6c7 Fri Oct 23 20:10:24 2026 +0000 Jonas Finnemann Jensen [crypto] Prepare to publish 3.0.8 (dart-lang/core#1026) 7c1c3700 Fri Oct 23 11:14:15 2026 -0700 Kevin Moore Tighten pull_request_label workflow permissions (dart-lang/core#1029) f01024fc Thu Oct 22 16:31:50 2026 -0700 Kevin Moore [collection] Share Iterable and Set tests across wrapper_test.dart (dart-lang/core#1028) c782eab4 Thu Oct 22 13:25:34 2026 +0200 Jonas Finnemann Jensen Update convert package README and add examples (dart-lang/core#999) dartdoc (https://github.com/dart-lang/dartdoc/compare/c0e19cf..db94437): db94437c Wed Oct 28 11:37:17 2026 +0100 Sarah Zakarias Add the doc-reference-target-differs warning (dart-lang/dartdoc#4306) b6e3980c Tue Oct 27 14:59:21 2026 +0100 Sarah Zakarias Only treat a doc comment as library documentation when it precedes a library directive (dart-lang/dartdoc#4303) 84a0141f Tue Oct 27 11:22:04 2026 +0100 Sarah Zakarias Add the unscoped-doc-reference warning (dart-lang/dartdoc#4305) b25bcd99 Thu Oct 22 15:56:17 2026 +0300 Sergey G. Grekhov Update/replace TODO in co19 tests (dart-lang/dartdoc#4299) 1e9e771e Thu Oct 22 12:18:48 2026 +0300 Sergey G. Grekhov `#4134`. Add more placement tests for `library` directives (dart-lang/dartdoc#4297) 17629ced Wed Oct 21 10:29:05 2026 -0700 Bob Nystrom Use newer function type syntax for parameters. (dart-lang/dartdoc#4290) f5928b1d Wed Oct 21 15:44:39 2026 +0300 Sergey G. Grekhov `#4134`. Add placement tests for enum values (dart-lang/dartdoc#4223) 24ae37f3 Wed Oct 21 11:18:07 2026 +0200 dependabot[bot] Bump test_reflective_loader from 0.4.0 to 0.6.0 (dart-lang/dartdoc#4296) ecosystem (https://github.com/dart-lang/ecosystem/compare/0ab0cfd..24b9ba8): 24b9ba8 Mon Oct 26 18:40:19 2026 -0700 Kevin Moore fix(repo_manage): increment patch version when transitioning to -wip (dart-lang/ecosystem#474) e1d4a04 Fri Oct 23 20:18:20 2026 +0000 dependabot[bot] Bump the github-actions group across 1 directory with 8 updates (dart-lang/ecosystem#473) 4b44357 Fri Oct 23 11:13:26 2026 -0700 Kevin Moore Tighten pull_request_label workflow permissions (dart-lang/ecosystem#472) i18n (https://github.com/dart-lang/i18n/compare/1f5ea2f..4c7b4ad): 4c7b4ad1 Fri Oct 23 11:14:00 2026 -0700 Kevin Moore Tighten pull_request_label workflow permissions (dart-lang/i18n#1113) 899251b1 Thu Oct 8 11:30:18 2026 +0200 Moritz [intl4x] Fix doc comment examples and verify them via {@example} in tests (dart-lang/i18n#1107) 5c8eb9d5 Thu Oct 8 10:27:58 2026 +0200 Moritz [intl4x] Fix YearStyle.withEra on ECMA when length is short or omitted (dart-lang/i18n#1105) b80bb04a Wed Sep 23 14:37:42 2026 +0200 Michael Thomsen Remove experiment flag no longer needed (dart-lang/i18n#1097) 766fd507 Wed Sep 23 13:59:56 2026 +0200 Moritz [intl4x] Mark DisplayNames API as @experimental and trigger CI on PR base edits (dart-lang/i18n#1098) 08de2f6f Fri Sep 18 12:49:50 2026 +0200 Moritz Rev package:intl4x to 1.0.0 and update status to preview (dart-lang/i18n#1088) native (https://github.com/dart-lang/native/compare/3cbe319..e0ca7c6): e0ca7c60f Wed Oct 28 12:08:25 2026 +0100 Michael Goderbauer [infra] Pin ubuntu-24.04 in workflows installing clang-15 (dart-lang/native#3771) eb09430a9 Tue Oct 27 10:43:22 2026 +0100 Michael Goderbauer [jni] Publish v1.1.1 (dart-lang/native#3765) 94b5f4337 Tue Oct 27 10:21:16 2026 +0100 Michael Goderbauer [jnigen] Pin ubuntu-24.04 in CI workflow (dart-lang/native#3766) 74cc078ee Tue Oct 27 09:29:23 2026 +0100 Michael Goderbauer [jni] Add ProGuard consumer rules for Kotlin classes used by suspend functions (dart-lang/native#3756) 0aa672fed Fri Oct 23 11:13:43 2026 -0700 Kevin Moore [infra] Tighten pull_request_label workflow permissions (dart-lang/native#3764) 8b11b6e01 Fri Oct 23 13:38:47 2026 +0200 Michael Goderbauer [jnigen] Bump AGP to 9.1.1 and KGP to 2.4.10 for Flutter beta (dart-lang/native#3758) protobuf (https://github.com/dart-lang/protobuf/compare/a73edc9..1d52301): 1d52301 Wed Oct 28 08:18:02 2026 -0700 Kevin Moore test(protoc_plugin): replace dart:mirrors in reserved_names_test (google/protobuf.dart#1104) shelf (https://github.com/dart-lang/shelf/compare/b66665b..73b2382): 73b2382 Thu Oct 22 10:43:29 2026 -0700 Kevin Moore shelf_router_generator: ignore invalid_use_of_internal_member on RouterEntry (dart-lang/shelf#548) shelf is held back at 73b2382, before dart-lang/shelf#547, because `pkgs/shelf/test/shelf_io_test.dart` now imports the unpublished `package:_shelf_compliance`, which breaks the shared `shelf_tests` target in google3. test (https://github.com/dart-lang/test/compare/d1afeb1..5967927): 5967927e Mon Oct 26 17:50:52 2026 -0700 Nate Bosch Diagnose browser connection failures and time them out with the suite load timeout (dart-lang/test#2788) 0692e8ae Mon Oct 26 16:29:27 2026 -0700 Kevin Moore Remove mirror_matchers.dart from package:matcher (dart-lang/test#2802) da21f85a Fri Oct 23 11:13:38 2026 -0700 Kevin Moore Tighten pull_request_label workflow permissions (dart-lang/test#2804) e18fd112 Thu Oct 22 15:38:51 2026 -0700 Nate Bosch Report tests that pass on retry as flaky (dart-lang/test#2801) b4ef80c0 Fri Oct 23 02:44:25 2026 +0600 Pranta Dutta Fix compact reporter crash when the terminal is too narrow (dart-lang/test#2799) e3a7f2b6 Tue Oct 20 15:51:34 2026 -0700 Nate Bosch Check that web entrypoints don't import VM-only libraries (dart-lang/test#2797) tools (https://github.com/dart-lang/tools/compare/eee87b1..3980dca): 3980dca39 Wed Oct 28 11:43:38 2026 +0100 Jonas Finnemann Jensen [html] Move contributors list from LICENSE to AUTHORS (dart-lang/tools#2733) 2866a7745 Wed Oct 28 11:13:19 2026 +0100 Jonas Finnemann Jensen [extension_discovery] Prepare for v2.1.1 release (dart-lang/tools#2727) 530feb74e Wed Oct 28 13:38:07 2026 +0530 Chandra ObulaReddy [csslib] Fix the aliceblue, antiquewhite and peru color values (dart-lang/tools#2732) d5c210271 Tue Oct 27 15:07:32 2026 -0700 Kevin Moore [source_span] Fix CR/CRLF highlighting, point-span context, and subspan (dart-lang/tools#2634) cbea5b08e Tue Oct 27 15:07:27 2026 -0700 Kevin Moore [string_scanner] Validate error() span bounds and test eager lastSpan (dart-lang/tools#2715) 22fd7a6a8 Tue Oct 27 15:07:20 2026 -0700 Kevin Moore [csslib] Fix parser, analyzer, polyfill, and printer crashes (dart-lang/tools#2638) webkit_inspection_protocol (https://github.com/google/webkit_inspection_protocol.dart/compare/762115a..2c255f2): 2c255f2 Thu Oct 22 14:18:44 2026 -0700 Kevin Moore Remove dart:mirrors and deprecate dom_model.dart and forwarder.dart (google/webkit_inspection_protocol.dart#141) web is held back at 4e60e61, before dart-lang/web#596, because it changes `package:web` signatures (e.g. `innerHTML=`, `parseFromString`, `Worker()`) from `JSAny` to `String` in ways that break callers in google3. Change-Id: Ia4253b35a91d7c05e34fe0e150ea4cb3e6628015 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/569660 Commit-Queue: Nate Bosch <[email protected]> Reviewed-by: Brian Quinlan <[email protected]>

kevmoo requested a review from a team as a code owner October 3, 2026 16:53

github-actions Bot added the package:source_span label Oct 3, 2026

gemini-code-assist Bot reviewed Oct 3, 2026

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Comment thread pkgs/source_span/lib/src/file.dart Resolved

kevmoo added 2 commits October 12, 2026 23:46

fix(source_span): check text in _FileSpan.operator ==

bb49256

[source_span] Preserve symmetric SourceSpan equality and add FileSpan…

132f32a

… equality tests

kevmoo requested a review from natebosch October 19, 2026 14:48

davidmorgan self-requested a review October 22, 2026 05:01

davidmorgan reviewed Oct 22, 2026

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Comment thread pkgs/source_span/lib/src/utils.dart Resolved

Comment thread pkgs/source_span/lib/src/highlighter.dart Resolved

Comment thread pkgs/source_span/test/span_test.dart Resolved

Comment thread pkgs/source_span/test/highlight_test.dart Resolved

kevmoo requested a review from davidmorgan October 22, 2026 15:53

davidmorgan reviewed Oct 23, 2026

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Comment thread pkgs/source_span/CHANGELOG.md Resolved

Comment thread pkgs/source_span/lib/src/utils.dart Resolved

Address review: strip CR from effective line end length in _scoreSpan…

8836ef2

…LineCandidate

kevmoo requested a review from davidmorgan October 23, 2026 17:15

kevmoo added 2 commits October 23, 2026 19:02

davidmorgan approved these changes Oct 26, 2026

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kevmoo merged commit d5c2102 into main Oct 27, 2026
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kevmoo deleted the fix-source_span branch October 27, 2026 22:07

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[source_span] Fix CR/CRLF highlighting, point-span context, and subspan - #2634

[source_span] Fix CR/CRLF highlighting, point-span context, and subspan#2634
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