Merge #31

31: extended_key_value_attributes r=jonas-schievink a=Veykril

see rust-lang/rust#78835, allows arbitrary expressions instead of just literals

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 = "1.12.2"
+version = "1.13.0"
 license = "MIT OR Apache-2.0"
 repository = "https://github.com/matklad/ungrammar"
 authors = ["Aleksey Kladov <aleksey.kladov@gmail.com>"]

rust.ungram

@@ -298,7 +298,7 @@ Visibility =
   'pub' ('(' 'in'? Path ')')?
 
 Attr =
-  '#' '!'? '[' Path ('=' Literal | TokenTree)? ']'
+  '#' '!'? '[' Path ('=' Expr | TokenTree)? ']'
 
 //****************************//
 // Statements and Expressions //