Use proper hygiene for `Parsers` and `Rule`

2 files changed, 8 insertions, 2 deletions

diff --git a/dhall_syntax/src/lib.rs b/dhall_syntax/src/lib.rs
index fb12af4..1636c8b 100644
--- a/dhall_syntax/src/lib.rs
+++ b/dhall_syntax/src/lib.rs
@@ -3,6 +3,7 @@
 #![feature(try_blocks)]
 #![feature(never_type)]
 #![feature(proc_macro_hygiene)]
+#![feature(type_alias_enum_variants)]
 #![allow(
     clippy::many_single_char_names,
     clippy::should_implement_trait,
diff --git a/dhall_syntax/src/parser.rs b/dhall_syntax/src/parser.rs
index fac6ecc..b1e429b 100644
--- a/dhall_syntax/src/parser.rs
+++ b/dhall_syntax/src/parser.rs
@@ -30,7 +30,7 @@ pub type ParseResult<T> = Result<T, ParseError>;
 #[derive(Debug, Clone)]
 struct ParseInput<'input, Rule>
 where
-    Rule: std::fmt::Debug + Copy + std::hash::Hash + Ord,
+    Rule: pest::RuleType,
 {
     pair: Pair<'input, Rule>,
     original_input_str: Rc<str>,
@@ -70,6 +70,11 @@ impl<'input> ParseInput<'input, Rule> {
     }
 }
 
+// Used to retrieve the `Rule` enum associated with the `Self` type in `parse_children`.
+trait PestConsumer {
+    type RuleEnum: pest::RuleType;
+}
+
 fn debug_pair(pair: Pair<Rule>) -> String {
     use std::fmt::Write;
     let mut s = String::new();
@@ -226,7 +231,7 @@ lazy_static::lazy_static! {
 
 struct Parsers;
 
-#[make_parser]
+#[make_parser(Rule)]
 impl Parsers {
     fn EOI(_: ParseInput<Rule>) -> ParseResult<()> {
         Ok(())