parse type const items

[yPin9]

Adds parser support for the unstable type const syntax from the
min_generic_const_args feature:

#![feature(min_generic_const_args)]
type const FOO: i32 = 2;

Previously rust-analyzer reported 8 syntax errors on this valid (nightly) code.

Closes #22038.

Changes

• rust.ungram: add optional 'type'? before 'const' in the Const rule.
• parser/grammar/items.rs: dispatch type followed by const to consts::konst in both item match sites (covers type const FOO and default type const FOO).
• parser/grammar/items/consts.rs: konst now p.eat(T![type]) before bumping const.
• Inline test type_const added; cargo xtask codegen regenerated AST nodes and test runner.

Test plan

• cargo test -p parser (including new type_const test)
• cargo test -p syntax
• Manual end-to-end check via rust-analyzer parse on the full issue reproduction — zero errors, correct CONST node with TYPE_KW + CONST_KW.
• Negative case (type const: i32 = 2;) still emits errors.

---

Assisted-by: Claude Opus 4.6

[reddevilmidzy]

Hello @yPin9, it seems I am still getting syntax errors in my rust-analyzer. How about you?

[ShoyuVanilla]

Hello @yPin9, it seems I am still getting syntax errors in my rust-analyzer. How about you?

Which version are you on? As this haven't been included in our stable releases (every Monday) yet, the issue wouldn't be fixed unless you are using the nightly release of rust-analyzer or have built it from the source

[reddevilmidzy]

Which version are you on? As this haven't been included in our stable releases (every Monday) yet, the issue wouldn't be fixed unless you are using the nightly release of rust-analyzer or have built it from the source

Ah, when I ran rust-analyzer --version, it showed rust-analyzer 1.97.0-nightly (e9e32aca 2026-04-17), so I thought the changes had been updated, but it seems the changes to r-l/r haven't arrived yet.

[ShoyuVanilla]

Yeah, we usually do subtree updates to rust-lang/rust on every Monday, after stable release

[ShoyuVanilla]

Yeah, we usually do subtree updates to rust-lang/rust on every Monday, after stable release

This is it rust-lang/rust#155556

[reddevilmidzy]

Yeah, we usually do subtree updates to rust-lang/rust on every Monday, after stable release

This is it rust-lang/rust#155556

thanks! I should update it quickly 😁