Merge #24

24: Fix incorrect rust.ungram rules for `Impl` and `RecordExprField` r=matklad a=Veykril

Regarding RecordExprField see https://rust-lang.zulipchat.com/#narrow/stream/185405-t-compiler.2Fwg-rls-2.2E0/topic/RecordExprField.20parse.20vs.20ungrammar.20definition
Regarding `const` position in `Impl` see https://github.com/oli-obk/rfcs/blob/const_generic_const_fn_bounds/text/0000-const-generic-const-fn-bounds.md#generic-bounds

Co-authored-by: Lukas Wirth <lukastw97@gmail.com>

Author: bors[bot]

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "ungrammar"
 description = "A DSL for describing concrete syntax trees"
-version = "1.9.2"
+version = "1.9.3"
 license = "MIT OR Apache-2.0"
 repository = "https://github.com/matklad/ungrammar"
 authors = ["Aleksey Kladov <aleksey.kladov@gmail.com>"]

rust.ungram

@@ -251,7 +251,7 @@ AssocItem =
 Impl =
   Attr* Visibility?
   'default'? 'unsafe'?
-  'impl' 'const'? GenericParamList? ('!'? trait:Type 'for')? self_ty:Type WhereClause?
+  'impl' GenericParamList? ('const'? '!'? trait:Type 'for')? self_ty:Type WhereClause?
   AssocItemList
 
 ExternBlock =
@@ -418,7 +418,7 @@ RecordExprFieldList =
   '}'
 
 RecordExprField =
-  Attr* NameRef (':' Expr)?
+  Attr* (NameRef ':')? Expr
 
 CallExpr =
   Attr* Expr ArgList