Simplify GenericParams grammar #1795
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The definition of GenericParams had separate productions for the cases of zero params and one-or-more params. Merge those two cases, to make the railroad diagram clearer.
This makes it easier to read the production from left to right: a GenericParam, zero or more (comma followed by GenericParam), optional trailing comma.
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Update books ## rust-lang/nomicon 1 commits in 0c10c30cc54736c5c194ce98c50e2de84eeb6e79..c76a20f0d987145dcedf05c5c073ce8d91f2e82a 2025-04-15 20:54:57 UTC to 2025-04-15 20:54:57 UTC - Say that dereferencing a pointer to a ZST is no longer undefined (rust-lang/nomicon#467) ## rust-lang/reference 7 commits in 3340922df189bddcbaad17dc3927d51a76bcd5ed..3bf3402aea982b876eb56c87da17b0685c6461d5 2025-04-18 13:44:45 UTC to 2025-04-17 17:27:01 UTC - Use `cfg(false)` instead of `cfg(FALSE)` (rust-lang/reference#1763) - Add `cfg(true)` and `cfg(false)` to conditional compilation (RFC 3695) (rust-lang/reference#1762) - Refactor rendering with `RenderCtx` (rust-lang/reference#1796) - attributes/codegen: update aarch64 features (rust-lang/reference#1791) - Simplify GenericParams grammar (rust-lang/reference#1795) - Add rule identifiers for the ABI chapter (rust-lang/reference#1793) - Remove broken footnote links from grammar summary (rust-lang/reference#1794)
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Update books ## rust-lang/nomicon 1 commits in 0c10c30cc54736c5c194ce98c50e2de84eeb6e79..c76a20f0d987145dcedf05c5c073ce8d91f2e82a 2025-04-15 20:54:57 UTC to 2025-04-15 20:54:57 UTC - Say that dereferencing a pointer to a ZST is no longer undefined (rust-lang/nomicon#467) ## rust-lang/reference 7 commits in 3340922df189bddcbaad17dc3927d51a76bcd5ed..3bf3402aea982b876eb56c87da17b0685c6461d5 2025-04-18 13:44:45 UTC to 2025-04-17 17:27:01 UTC - Use `cfg(false)` instead of `cfg(FALSE)` (rust-lang/reference#1763) - Add `cfg(true)` and `cfg(false)` to conditional compilation (RFC 3695) (rust-lang/reference#1762) - Refactor rendering with `RenderCtx` (rust-lang/reference#1796) - attributes/codegen: update aarch64 features (rust-lang/reference#1791) - Simplify GenericParams grammar (rust-lang/reference#1795) - Add rule identifiers for the ABI chapter (rust-lang/reference#1793) - Remove broken footnote links from grammar summary (rust-lang/reference#1794)
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Rollup merge of rust-lang#140124 - rustbot:docs-update, r=ehuss Update books ## rust-lang/nomicon 1 commits in 0c10c30cc54736c5c194ce98c50e2de84eeb6e79..c76a20f0d987145dcedf05c5c073ce8d91f2e82a 2025-04-15 20:54:57 UTC to 2025-04-15 20:54:57 UTC - Say that dereferencing a pointer to a ZST is no longer undefined (rust-lang/nomicon#467) ## rust-lang/reference 7 commits in 3340922df189bddcbaad17dc3927d51a76bcd5ed..3bf3402aea982b876eb56c87da17b0685c6461d5 2025-04-18 13:44:45 UTC to 2025-04-17 17:27:01 UTC - Use `cfg(false)` instead of `cfg(FALSE)` (rust-lang/reference#1763) - Add `cfg(true)` and `cfg(false)` to conditional compilation (RFC 3695) (rust-lang/reference#1762) - Refactor rendering with `RenderCtx` (rust-lang/reference#1796) - attributes/codegen: update aarch64 features (rust-lang/reference#1791) - Simplify GenericParams grammar (rust-lang/reference#1795) - Add rule identifiers for the ABI chapter (rust-lang/reference#1793) - Remove broken footnote links from grammar summary (rust-lang/reference#1794)
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Update books ## rust-lang/nomicon 1 commits in 0c10c30cc54736c5c194ce98c50e2de84eeb6e79..c76a20f0d987145dcedf05c5c073ce8d91f2e82a 2025-04-15 20:54:57 UTC to 2025-04-15 20:54:57 UTC - Say that dereferencing a pointer to a ZST is no longer undefined (rust-lang/nomicon#467) ## rust-lang/reference 7 commits in 3340922df189bddcbaad17dc3927d51a76bcd5ed..3bf3402aea982b876eb56c87da17b0685c6461d5 2025-04-18 13:44:45 UTC to 2025-04-17 17:27:01 UTC - Use `cfg(false)` instead of `cfg(FALSE)` (rust-lang/reference#1763) - Add `cfg(true)` and `cfg(false)` to conditional compilation (RFC 3695) (rust-lang/reference#1762) - Refactor rendering with `RenderCtx` (rust-lang/reference#1796) - attributes/codegen: update aarch64 features (rust-lang/reference#1791) - Simplify GenericParams grammar (rust-lang/reference#1795) - Add rule identifiers for the ABI chapter (rust-lang/reference#1793) - Remove broken footnote links from grammar summary (rust-lang/reference#1794)
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When reading through the grammar, I found it surprising that GenericParams had
two separate alternatives, one for the empty case and one for the one-or-more
case. That seemed to obfuscate that GenericParams contains zero-or-more
GenericParam. This structure likely arose in order to express the optional
trailing comma correctly; however, it's possible to express that in another
way.
Rework
GenericParamsto have a single production that uses?, which thendeduplicates the surrounding
<and>, and (in my opinion) simplifies thehandling of the trailing comma.