feat(css): add support for `sass()` in SCSS conditional expressions by denbezrukov · Pull Request #9414 · biomejs/biome

denbezrukov · 2026-03-09T08:28:19Z

Summary

Improves SCSS expression parsing for two Sass syntax gaps.

Biome now keeps unparenthesized !important inside SCSS variable values instead of misparsing it
as a variable modifier, and it recognizes if(sass(...): ...; else: ...;) in SCSS files.

Test Plan

new tests

changeset-bot · 2026-03-09T08:28:26Z

⚠️ No Changeset found

Latest commit: 8134566

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

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github-actions · 2026-03-09T08:31:54Z

Parser conformance results on

js/262

Test result	`main` count	This PR count	Difference
Total	53009	53009	0
Passed	51789	51789	0
Failed	1178	1178	0
Panics	42	42	0
Coverage	97.70%	97.70%	0.00%

jsx/babel

Test result	`main` count	This PR count	Difference
Total	38	38	0
Passed	37	37	0
Failed	1	1	0
Panics	0	0	0
Coverage	97.37%	97.37%	0.00%

markdown/commonmark

Test result	`main` count	This PR count	Difference
Total	652	652	0
Passed	652	652	0
Failed	0	0	0
Panics	0	0	0
Coverage	100.00%	100.00%	0.00%

symbols/microsoft

Test result	`main` count	This PR count	Difference
Total	5466	5466	0
Passed	1915	1915	0
Failed	3551	3551	0
Panics	0	0	0
Coverage	35.03%	35.03%	0.00%

ts/babel

Test result	`main` count	This PR count	Difference
Total	636	636	0
Passed	568	568	0
Failed	68	68	0
Panics	0	0	0
Coverage	89.31%	89.31%	0.00%

ts/microsoft

Test result	`main` count	This PR count	Difference
Total	18875	18875	0
Passed	13014	13014	0
Failed	5860	5860	0
Panics	1	1	0
Coverage	68.95%	68.95%	0.00%

codspeed-hq · 2026-03-09T08:35:09Z

Merging this PR will not alter performance

✅ 29 untouched benchmarks
⏩ 187 skipped benchmarks¹

_{Comparing db/scss-if (8134566) with main (77fe3a4)}

187 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. ↩

coderabbitai · 2026-03-09T08:37:13Z

No actionable comments were generated in the recent review. 🎉

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📥 Commits

Reviewing files that changed from the base of the PR and between 8ceea05 and dcc26fe.

⛔ Files ignored due to path filters (5)

crates/biome_css_parser/tests/css_test_suite/error/function/if.css.snap is excluded by !**/*.snap and included by **
crates/biome_css_parser/tests/css_test_suite/error/function/scss_qualified_function.css.snap is excluded by !**/*.snap and included by **
crates/biome_css_parser/tests/css_test_suite/error/property/bracketed_value_separators.css.snap is excluded by !**/*.snap and included by **
crates/biome_css_parser/tests/css_test_suite/error/scss/declaration/invalid-modifier.scss.snap is excluded by !**/*.snap and included by **
crates/biome_css_parser/tests/css_test_suite/error/scss/declaration/modifier-recovery.scss.snap is excluded by !**/*.snap and included by **

📒 Files selected for processing (3)

crates/biome_css_parser/src/syntax/parse_error.rs
crates/biome_css_parser/tests/css_test_suite/error/scss/declaration/invalid-modifier.scss
crates/biome_css_parser/tests/css_test_suite/error/scss/declaration/modifier-recovery.scss

💤 Files with no reviewable changes (3)

crates/biome_css_parser/src/syntax/parse_error.rs
crates/biome_css_parser/tests/css_test_suite/error/scss/declaration/invalid-modifier.scss
crates/biome_css_parser/tests/css_test_suite/error/scss/declaration/modifier-recovery.scss

Walkthrough

Adds SCSS sass(...) support to the CSS if() pipeline: new grammar node CssIfSassTest, lexer keyword sass, parser detection and parsing for sass tests (with SCSS expression options and variable-modifier awareness), formatter rule and wiring for the new node, test cases exercising the syntax, and small re-exports to share helper predicates across SCSS declaration parsing.

Possibly related PRs

feat(css): add support for parsing and formatting the CSS if function #8111: Prior work on CSS if() parsing/formatting that this change extends by adding the CssIfSassTest variant.
refactor(css_parser): split function parser into modules #9325: Refactors function/call parsing (function detection helpers) that this PR augments to recognise sass(...) as an if-test start.
feat(css): improve scss declaration modifier recovery #9352: Changes SCSS variable-modifier parsing and introduces helpers (is_at_scss_variable_modifier_start) used by the new SCSS expression parsing paths.

Suggested labels

L-SCSS

Suggested reviewers

ematipico
dyc3

🚥 Pre-merge checks | ✅ 2

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main change: adding support for `sass()` within SCSS conditional expressions, which is reflected throughout the changeset.
Description check	✅ Passed	The description relates to the changeset by mentioning SCSS variable value parsing and `if(sass(...))` support, though it could be more detailed about the specific implementation.

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🧪 Generate unit tests (beta)

Create PR with unit tests
Post copyable unit tests in a comment
Commit unit tests in branch db/scss-if

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coderabbitai

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@crates/biome_css_parser/src/syntax/scss/expression/mod.rs`:
- Around line 63-70: The recovery logic must also stop before variable modifiers
so modifiers like "!default" / "!global" aren't consumed into a malformed
expression: update the recovery boundary to mirror variable_value's boundary
(i.e., respect stops_before_variable_modifiers). Specifically, modify the
recovery path that currently uses recovery_end_ts() so it checks for variable
modifiers and treats them as stopping tokens (or pass the same end_ts that
includes that stop), and apply the same change to the other analogous
constructor(s) referenced around lines 91-93; refer to variable_value,
recovery_end_ts, and the stops_before_variable_modifiers flag when locating
where to add the stop-for-modifiers check.

ℹ️ Review info

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Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 4c76c3bf-7179-407e-8692-bb8c1199d771

📥 Commits

Reviewing files that changed from the base of the PR and between 9c95b13 and 426c6aa.

⛔ Files ignored due to path filters (10)

crates/biome_css_factory/src/generated/node_factory.rs is excluded by !**/generated/**, !**/generated/** and included by **
crates/biome_css_factory/src/generated/syntax_factory.rs is excluded by !**/generated/**, !**/generated/** and included by **
crates/biome_css_formatter/tests/specs/css/scss/expression/edge-cases.scss.snap is excluded by !**/*.snap and included by **
crates/biome_css_parser/tests/css_test_suite/error/function/if.css.snap is excluded by !**/*.snap and included by **
crates/biome_css_parser/tests/css_test_suite/ok/scss/value/if-disambiguation.scss.snap is excluded by !**/*.snap and included by **
crates/biome_css_parser/tests/css_test_suite/ok/scss/value/list-important-item.scss.snap is excluded by !**/*.snap and included by **
crates/biome_css_syntax/src/generated/kind.rs is excluded by !**/generated/**, !**/generated/** and included by **
crates/biome_css_syntax/src/generated/macros.rs is excluded by !**/generated/**, !**/generated/** and included by **
crates/biome_css_syntax/src/generated/nodes.rs is excluded by !**/generated/**, !**/generated/** and included by **
crates/biome_css_syntax/src/generated/nodes_mut.rs is excluded by !**/generated/**, !**/generated/** and included by **

📒 Files selected for processing (21)

crates/biome_css_formatter/src/css/any/if_test.rs
crates/biome_css_formatter/src/css/auxiliary/if_sass_test.rs
crates/biome_css_formatter/src/css/auxiliary/mod.rs
crates/biome_css_formatter/src/generated.rs
crates/biome_css_formatter/tests/specs/css/scss/expression/edge-cases.scss
crates/biome_css_parser/src/lexer/mod.rs
crates/biome_css_parser/src/lexer/tests.rs
crates/biome_css_parser/src/syntax/scss/declaration/mod.rs
crates/biome_css_parser/src/syntax/scss/declaration/variable.rs
crates/biome_css_parser/src/syntax/scss/declaration/variable_modifier.rs
crates/biome_css_parser/src/syntax/scss/expression/list.rs
crates/biome_css_parser/src/syntax/scss/expression/mod.rs
crates/biome_css_parser/src/syntax/scss/mod.rs
crates/biome_css_parser/src/syntax/value/function/call.rs
crates/biome_css_parser/src/syntax/value/if.rs
crates/biome_css_parser/tests/css_test_suite/error/function/if.css
crates/biome_css_parser/tests/css_test_suite/ok/scss/value/if-disambiguation.scss
crates/biome_css_parser/tests/css_test_suite/ok/scss/value/list-important-item.scss
crates/biome_grit_patterns/src/grit_target_language/css_target_language/generated_mappings.rs
xtask/codegen/css.ungram
xtask/codegen/src/css_kinds_src.rs

crates/biome_css_parser/src/syntax/scss/expression/mod.rs

crates/biome_css_parser/tests/css_test_suite/error/function/if.css.snap

…cs parsing

feat(css): add support for sass() in SCSS conditional expressions

426c6aa

github-actions bot added A-Parser Area: parser A-Formatter Area: formatter A-Tooling Area: internal tools L-CSS Language: CSS L-Grit Language: GritQL labels Mar 9, 2026

[autofix.ci] apply automated fixes

8ceea05

coderabbitai bot reviewed Mar 9, 2026

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crates/biome_css_parser/src/syntax/scss/expression/mod.rs Show resolved Hide resolved

ematipico reviewed Mar 9, 2026

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crates/biome_css_parser/tests/css_test_suite/error/function/if.css.snap Outdated Show resolved Hide resolved

denbezrukov added 2 commits March 9, 2026 12:00

fix(css): remove invalid SCSS modifier handling and improve diagnosti…

dcc26fe

…cs parsing

fix(css): remove redundant SCSS syntax hints

8134566

ematipico approved these changes Mar 9, 2026

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denbezrukov merged commit 0536fd3 into main Mar 9, 2026
18 checks passed

denbezrukov deleted the db/scss-if branch March 9, 2026 10:48

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feat(css): add support for `sass()` in SCSS conditional expressions#9414

feat(css): add support for `sass()` in SCSS conditional expressions#9414
denbezrukov merged 4 commits intomainfrom
db/scss-if

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denbezrukov commented Mar 9, 2026

Summary

Test Plan

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github-actions bot commented Mar 9, 2026

Parser conformance results on

js/262

jsx/babel

markdown/commonmark

symbols/microsoft

ts/babel

ts/microsoft

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Merging this PR will not alter performance

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Walkthrough

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