Support non-ASCII Unicode in grammar rule names#2196
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The grammar currently supports only ASCII rule names. We want to support non-ASCII Unicode symbols such as `⊥` (bottom) since we plan to add that rule. In this commit, we add `is_name_start` and `is_name_continue` predicates that centralize the decision of what can appear in a rule name. `is_name_start` accepts alphabetic characters, underscores, and non-ASCII characters; `is_name_continue` accepts alphanumeric characters, underscores, and non-ASCII characters. We use `is_name_start` in the `parse_expr1` condition that routes to `parse_nonterminal`. The previous condition (`is_alphanumeric`) was slightly misaligned with what `parse_name` actually accepts -- it included digits (which `parse_name` rejects) and excluded underscores (which `parse_name` accepts). Using `is_name_start` makes the dispatch condition match `parse_name` exactly. The `NAMES_RE` regex in `mdbook-spec` encodes the same name-matching logic as a regex pattern, so let's add a comment tying it to the predicates.
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Update books ## rust-embedded/book 4 commits in 99d0341ff4e06757490af8fceee790c4ede50bc0..e88aa4403b4bf2071c8df9509160477e40179099 2026-02-28 20:13:44 UTC to 2026-02-28 20:07:25 UTC - Clarify that a mini usb cable is used on the STM32F3DISCOVERY (rust-embedded/book#381) - Update outdated qemu documentation (rust-embedded/book#403) - Add TRACE32 to Debuggers section (rust-embedded/book#406) - Add a link to Rust for Zephyr (rust-embedded/book#407) ## rust-lang/nomicon 4 commits in b8f254a991b8b7e8f704527f0d4f343a4697dfa9..cc6a6bae8c3bfa389974e533c54694662c1a9de6 2026-02-27 23:27:18 UTC to 2026-02-26 22:57:03 UTC - Fix `Vec::push_all` ptr code in exception-safety (rust-lang/nomicon#418) - Clarify parameter and argument compatibility (rust-lang/nomicon#516) - Improve grammar in Variance section (rust-lang/nomicon#515) - Explicit `extern "C"` ABI for FFI (rust-lang/nomicon#520) ## rust-lang/reference 7 commits in 50a1075e879be75aeec436252c84eef0fad489f4..c49e89cc8c7c2c43ca625a8d5b7ad9a53a9ce978 2026-03-04 15:39:00 UTC to 2026-03-01 06:34:18 UTC - Resolve grammar rules in link reference definitions (rust-lang/reference#2198) - Support non-ASCII Unicode in grammar rule names (rust-lang/reference#2196) - Fix grammar for block comments (rust-lang/reference#2191) - Fix an EN grammar error & add an item to place expr context list (rust-lang/reference#2189) - Align attribute template with applied conventions (rust-lang/reference#2194) - Update shebang (rust-lang/reference#2192) - Remove RESERVED_NUMBER (rust-lang/reference#2193)
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Update books ## rust-embedded/book 4 commits in 99d0341ff4e06757490af8fceee790c4ede50bc0..e88aa4403b4bf2071c8df9509160477e40179099 2026-02-28 20:13:44 UTC to 2026-02-28 20:07:25 UTC - Clarify that a mini usb cable is used on the STM32F3DISCOVERY (rust-embedded/book#381) - Update outdated qemu documentation (rust-embedded/book#403) - Add TRACE32 to Debuggers section (rust-embedded/book#406) - Add a link to Rust for Zephyr (rust-embedded/book#407) ## rust-lang/nomicon 4 commits in b8f254a991b8b7e8f704527f0d4f343a4697dfa9..cc6a6bae8c3bfa389974e533c54694662c1a9de6 2026-02-27 23:27:18 UTC to 2026-02-26 22:57:03 UTC - Fix `Vec::push_all` ptr code in exception-safety (rust-lang/nomicon#418) - Clarify parameter and argument compatibility (rust-lang/nomicon#516) - Improve grammar in Variance section (rust-lang/nomicon#515) - Explicit `extern "C"` ABI for FFI (rust-lang/nomicon#520) ## rust-lang/reference 7 commits in 50a1075e879be75aeec436252c84eef0fad489f4..c49e89cc8c7c2c43ca625a8d5b7ad9a53a9ce978 2026-03-04 15:39:00 UTC to 2026-03-01 06:34:18 UTC - Resolve grammar rules in link reference definitions (rust-lang/reference#2198) - Support non-ASCII Unicode in grammar rule names (rust-lang/reference#2196) - Fix grammar for block comments (rust-lang/reference#2191) - Fix an EN grammar error & add an item to place expr context list (rust-lang/reference#2189) - Align attribute template with applied conventions (rust-lang/reference#2194) - Update shebang (rust-lang/reference#2192) - Remove RESERVED_NUMBER (rust-lang/reference#2193)
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Update books ## rust-embedded/book 4 commits in 99d0341ff4e06757490af8fceee790c4ede50bc0..e88aa4403b4bf2071c8df9509160477e40179099 2026-02-28 20:13:44 UTC to 2026-02-28 20:07:25 UTC - Clarify that a mini usb cable is used on the STM32F3DISCOVERY (rust-embedded/book#381) - Update outdated qemu documentation (rust-embedded/book#403) - Add TRACE32 to Debuggers section (rust-embedded/book#406) - Add a link to Rust for Zephyr (rust-embedded/book#407) ## rust-lang/nomicon 4 commits in b8f254a991b8b7e8f704527f0d4f343a4697dfa9..cc6a6bae8c3bfa389974e533c54694662c1a9de6 2026-02-27 23:27:18 UTC to 2026-02-26 22:57:03 UTC - Fix `Vec::push_all` ptr code in exception-safety (rust-lang/nomicon#418) - Clarify parameter and argument compatibility (rust-lang/nomicon#516) - Improve grammar in Variance section (rust-lang/nomicon#515) - Explicit `extern "C"` ABI for FFI (rust-lang/nomicon#520) ## rust-lang/reference 7 commits in 50a1075e879be75aeec436252c84eef0fad489f4..c49e89cc8c7c2c43ca625a8d5b7ad9a53a9ce978 2026-03-04 15:39:00 UTC to 2026-03-01 06:34:18 UTC - Resolve grammar rules in link reference definitions (rust-lang/reference#2198) - Support non-ASCII Unicode in grammar rule names (rust-lang/reference#2196) - Fix grammar for block comments (rust-lang/reference#2191) - Fix an EN grammar error & add an item to place expr context list (rust-lang/reference#2189) - Align attribute template with applied conventions (rust-lang/reference#2194) - Update shebang (rust-lang/reference#2192) - Remove RESERVED_NUMBER (rust-lang/reference#2193)
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Rollup merge of #153619 - rustbot:docs-update, r=ehuss Update books ## rust-embedded/book 4 commits in 99d0341ff4e06757490af8fceee790c4ede50bc0..e88aa4403b4bf2071c8df9509160477e40179099 2026-02-28 20:13:44 UTC to 2026-02-28 20:07:25 UTC - Clarify that a mini usb cable is used on the STM32F3DISCOVERY (rust-embedded/book#381) - Update outdated qemu documentation (rust-embedded/book#403) - Add TRACE32 to Debuggers section (rust-embedded/book#406) - Add a link to Rust for Zephyr (rust-embedded/book#407) ## rust-lang/nomicon 4 commits in b8f254a991b8b7e8f704527f0d4f343a4697dfa9..cc6a6bae8c3bfa389974e533c54694662c1a9de6 2026-02-27 23:27:18 UTC to 2026-02-26 22:57:03 UTC - Fix `Vec::push_all` ptr code in exception-safety (rust-lang/nomicon#418) - Clarify parameter and argument compatibility (rust-lang/nomicon#516) - Improve grammar in Variance section (rust-lang/nomicon#515) - Explicit `extern "C"` ABI for FFI (rust-lang/nomicon#520) ## rust-lang/reference 7 commits in 50a1075e879be75aeec436252c84eef0fad489f4..c49e89cc8c7c2c43ca625a8d5b7ad9a53a9ce978 2026-03-04 15:39:00 UTC to 2026-03-01 06:34:18 UTC - Resolve grammar rules in link reference definitions (rust-lang/reference#2198) - Support non-ASCII Unicode in grammar rule names (rust-lang/reference#2196) - Fix grammar for block comments (rust-lang/reference#2191) - Fix an EN grammar error & add an item to place expr context list (rust-lang/reference#2189) - Align attribute template with applied conventions (rust-lang/reference#2194) - Update shebang (rust-lang/reference#2192) - Remove RESERVED_NUMBER (rust-lang/reference#2193)
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The grammar currently supports only ASCII rule names. We want to support non-ASCII Unicode symbols such as
⊥(bottom) since we plan to add that rule.In this commit, we add
is_name_startandis_name_continuepredicates that centralize the decision of what can appear in a rule name.is_name_startaccepts alphabetic characters, underscores, and non-ASCII characters;is_name_continueaccepts alphanumeric characters, underscores, and non-ASCII characters.We use
is_name_startin theparse_expr1condition that routes toparse_nonterminal. The previous condition (is_alphanumeric) was slightly misaligned with whatparse_nameactually accepts -- it included digits (whichparse_namerejects) and excluded underscores (whichparse_nameaccepts). Usingis_name_startmakes the dispatch condition matchparse_nameexactly.The
NAMES_REregex inmdbook-specencodes the same name-matching logic as a regex pattern, so let's add a comment tying it to the predicates.cc @ehuss