fix(parse/tailwind): fix lexing variants that start with numbers #7966
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WalkthroughThe Tailwind parser's lexer has been updated to recognise digits as valid characters for starting base token names, alongside ASCII letters. Previously, only letters could initiate a base name. A corresponding test case has been added to verify parsing of Tailwind classes beginning with numeric characters, such as "2xl:table". Suggested labels
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🧹 Nitpick comments (1)
crates/biome_tailwind_parser/tests/tailwind_specs/ok/variants/starts-with-number.txt (1)
1-1: Good test case, consider expanding coverage.The test correctly demonstrates parsing of a digit-starting variant (
2xl:table). Consider adding a few more cases to strengthen coverage: chained variants (e.g.,2xl:hover:table), other numeric breakpoints (3xl:flex), or with modifiers (2xl:text-lg/relaxed).
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crates/biome_tailwind_parser/tests/tailwind_specs/ok/variants/starts-with-number.txt.snapis excluded by!**/*.snapand included by**
📒 Files selected for processing (2)
crates/biome_tailwind_parser/src/lexer/mod.rs(1 hunks)crates/biome_tailwind_parser/tests/tailwind_specs/ok/variants/starts-with-number.txt(1 hunks)
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**/*.{rs,toml}
📄 CodeRabbit inference engine (CONTRIBUTING.md)
Format Rust and TOML files before committing (e.g., via
just f)
Files:
crates/biome_tailwind_parser/src/lexer/mod.rs
**/*.rs
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Files:
crates/biome_tailwind_parser/src/lexer/mod.rs
🧠 Learnings (14)
📓 Common learnings
Learnt from: ematipico
Repo: biomejs/biome PR: 7852
File: crates/biome_css_parser/src/syntax/property/mod.rs:161-168
Timestamp: 2025-10-25T07:22:18.540Z
Learning: In the Biome CSS parser, lexer token emission should not be gated behind parser options like `is_tailwind_directives_enabled()`. The lexer must emit correct tokens regardless of parser options to enable accurate diagnostics and error messages when the syntax is used incorrectly.
📚 Learning: 2025-10-15T09:22:15.851Z
Learnt from: CR
Repo: biomejs/biome PR: 0
File: crates/biome_formatter/CONTRIBUTING.md:0-0
Timestamp: 2025-10-15T09:22:15.851Z
Learning: Applies to crates/biome_formatter/tests/spec_tests.rs : In tests/spec_tests.rs, generate tests with `tests_macros::gen_tests! {"tests/specs/html/**/*.html", crate::spec_test::run, ""}`
Applied to files:
crates/biome_tailwind_parser/tests/tailwind_specs/ok/variants/starts-with-number.txt
📚 Learning: 2025-10-24T21:24:58.650Z
Learnt from: CR
Repo: biomejs/biome PR: 0
File: crates/biome_analyze/CONTRIBUTING.md:0-0
Timestamp: 2025-10-24T21:24:58.650Z
Learning: Applies to crates/biome_analyze/crates/*_analyze/tests/specs/**/{invalid*,valid*}.* : Name snapshot test files with invalid* and valid* prefixes to indicate reported vs non-reported cases
Applied to files:
crates/biome_tailwind_parser/tests/tailwind_specs/ok/variants/starts-with-number.txt
📚 Learning: 2025-10-15T09:22:15.851Z
Learnt from: CR
Repo: biomejs/biome PR: 0
File: crates/biome_formatter/CONTRIBUTING.md:0-0
Timestamp: 2025-10-15T09:22:15.851Z
Learning: Applies to crates/biome_formatter/tests/** : Create a tests directory containing a specs subfolder and the files spec_test.rs, spec_tests.rs, and language.rs
Applied to files:
crates/biome_tailwind_parser/tests/tailwind_specs/ok/variants/starts-with-number.txt
📚 Learning: 2025-10-24T21:24:58.650Z
Learnt from: CR
Repo: biomejs/biome PR: 0
File: crates/biome_analyze/CONTRIBUTING.md:0-0
Timestamp: 2025-10-24T21:24:58.650Z
Learning: Applies to crates/biome_analyze/crates/*_analyze/**/src/**/lint/**/*.rs : Use options/full_options/use_options code block modifiers as specified to demonstrate configuration in docs; keep modifier order consistent
Applied to files:
crates/biome_tailwind_parser/tests/tailwind_specs/ok/variants/starts-with-number.txt
📚 Learning: 2025-10-24T21:24:58.650Z
Learnt from: CR
Repo: biomejs/biome PR: 0
File: crates/biome_analyze/CONTRIBUTING.md:0-0
Timestamp: 2025-10-24T21:24:58.650Z
Learning: Applies to crates/biome_analyze/crates/*_analyze/**/src/**/lint/**/*.rs : Avoid avoidable string allocations; compare against &str or TokenText rather than allocating Strings
Applied to files:
crates/biome_tailwind_parser/src/lexer/mod.rs
📚 Learning: 2025-10-15T09:22:46.002Z
Learnt from: CR
Repo: biomejs/biome PR: 0
File: crates/biome_js_formatter/CONTRIBUTING.md:0-0
Timestamp: 2025-10-15T09:22:46.002Z
Learning: Applies to crates/biome_js_formatter/**/*.rs : For non-mandatory tokens, use the provided helper constructors (e.g., `token`, `space_token`, `dynamic_token`)
Applied to files:
crates/biome_tailwind_parser/src/lexer/mod.rs
📚 Learning: 2025-10-15T09:24:31.042Z
Learnt from: CR
Repo: biomejs/biome PR: 0
File: crates/biome_parser/CONTRIBUTING.md:0-0
Timestamp: 2025-10-15T09:24:31.042Z
Learning: Applies to crates/biome_parser/crates/**/src/lexer/mod.rs : Create a lexer module at crates/<parser_crate>/src/lexer/mod.rs
Applied to files:
crates/biome_tailwind_parser/src/lexer/mod.rs
📚 Learning: 2025-10-15T09:24:31.042Z
Learnt from: CR
Repo: biomejs/biome PR: 0
File: crates/biome_parser/CONTRIBUTING.md:0-0
Timestamp: 2025-10-15T09:24:31.042Z
Learning: Lexer must implement the biome_parser::Lexer trait
Applied to files:
crates/biome_tailwind_parser/src/lexer/mod.rs
📚 Learning: 2025-10-15T09:22:46.002Z
Learnt from: CR
Repo: biomejs/biome PR: 0
File: crates/biome_js_formatter/CONTRIBUTING.md:0-0
Timestamp: 2025-10-15T09:22:46.002Z
Learning: Applies to crates/biome_js_formatter/**/*.rs : Do not attempt to fix code; if a mandatory token/node is missing, return `None` instead
Applied to files:
crates/biome_tailwind_parser/src/lexer/mod.rs
📚 Learning: 2025-10-15T09:22:46.002Z
Learnt from: CR
Repo: biomejs/biome PR: 0
File: crates/biome_js_formatter/CONTRIBUTING.md:0-0
Timestamp: 2025-10-15T09:22:46.002Z
Learning: Applies to crates/biome_js_formatter/**/*.rs : When a token is mandatory and present in the AST, use the AST-provided token (e.g., `node.l_paren_token().format()`) instead of emitting a static token
Applied to files:
crates/biome_tailwind_parser/src/lexer/mod.rs
📚 Learning: 2025-10-25T07:22:18.540Z
Learnt from: ematipico
Repo: biomejs/biome PR: 7852
File: crates/biome_css_parser/src/syntax/property/mod.rs:161-168
Timestamp: 2025-10-25T07:22:18.540Z
Learning: In the Biome CSS parser, lexer token emission should not be gated behind parser options like `is_tailwind_directives_enabled()`. The lexer must emit correct tokens regardless of parser options to enable accurate diagnostics and error messages when the syntax is used incorrectly.
Applied to files:
crates/biome_tailwind_parser/src/lexer/mod.rs
📚 Learning: 2025-10-24T21:24:58.650Z
Learnt from: CR
Repo: biomejs/biome PR: 0
File: crates/biome_analyze/CONTRIBUTING.md:0-0
Timestamp: 2025-10-24T21:24:58.650Z
Learning: Applies to crates/biome_analyze/crates/*_analyze/**/src/**/lint/**/*.rs : Set the language field in declare_lint_rule! to the most appropriate dialect (js/jsx/ts/tsx)
Applied to files:
crates/biome_tailwind_parser/src/lexer/mod.rs
📚 Learning: 2025-10-24T21:24:58.650Z
Learnt from: CR
Repo: biomejs/biome PR: 0
File: crates/biome_analyze/CONTRIBUTING.md:0-0
Timestamp: 2025-10-24T21:24:58.650Z
Learning: Applies to crates/biome_analyze/crates/*_analyze/**/src/**/lint/**/*.rs : Prefer conventional naming families when applicable: use<Framework>..., noConstant<Concept>, noDuplicate<Concept>, noEmpty<Concept>, noExcessive<Concept>, noRedundant<Concept>, noUnused<Concept>, noUseless<Concept>, noInvalid<Concept>, useValid<Concept>, noUnknown<Concept>, noMisleading<Concept>, noRestricted<Concept>, noUndeclared<Concept>, noUnsafe<Concept>, useConsistent<Concept>, useShorthand<Concept>
Applied to files:
crates/biome_tailwind_parser/src/lexer/mod.rs
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- GitHub Check: Documentation
- GitHub Check: Lint project (depot-windows-2022)
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🔇 Additional comments (2)
crates/biome_tailwind_parser/src/lexer/mod.rs (2)
84-84: Asymmetry is intentional and correct — verified against Tailwind's actual syntax rules.Tailwind CSS doesn't support negative variants with digit-starting base names like
-2xl:text-lg. Negative signs apply to utilities (e.g.-mt-4), not variant names, and variant prefixes that start with digits must come before the utility. Line 84's restriction to alphabetic characters after the negative sign is therefore correct—there's no intentional asymmetry, just proper adherence to Tailwind's syntax.
61-61: Change correctly enables numeric breakpoint variants.The modification at line 61 from
is_ascii_alphabetic()tois_ascii_alphanumeric()is spot-on. The test filestarts-with-number.txtconfirms this handles2xl:tableand similar digit-starting Tailwind breakpoint variants properly.The asymmetry with line 84 (which remains alphabetic-only in the
consume_token_saw_negative()function) is intentional and correct—negative breakpoint variants aren't valid in Tailwind, so that path doesn't need digit support.
Summary
Fixes lexing for candidates that look like
2xl:text-lgTest Plan
added tests
Docs