Add support for + on GAT bounds

Author: tmandry

chalk-parse/src/ast.rs

@@ -54,7 +54,7 @@ pub struct TraitFlags {
 pub struct AssocTyDefn {
     pub name: Identifier,
     pub parameter_kinds: Vec<ParameterKind>,
-    pub bound: Option<TraitRef>,
+    pub bounds: Vec<TraitBound>,
     pub where_clauses: Vec<QuantifiedWhereClause>,
 }
 
@@ -177,6 +177,11 @@ impl PolarizedTraitRef {
     }
 }
 
+pub struct TraitBound {
+    pub trait_name: Identifier,
+    pub args_no_self: Vec<Parameter>,
+}
+
 #[derive(Copy, Clone, Debug)]
 pub struct Identifier {
     pub str: InternedString,

chalk-parse/src/parser.lalrpop

@@ -72,25 +72,23 @@ TraitDefn: TraitDefn = {
 };
 
 AssocTyDefn: AssocTyDefn = {
-    "type" <name:Id> <p:Angle<ParameterKind>> <b:(":" <Id> <Angle<Parameter>>)?>
+    "type" <name:Id> <p:Angle<ParameterKind>> <b:(":" <Plus<TraitBound>>)?>
         <w:QuantifiedWhereClauses> ";" =>
     {
-        let bound = match b {
-            Some((t, a)) => {
-                let mut args = vec![Parameter::Ty(Ty::Id{ name })];
-                args.extend(a);
-                Some(TraitRef {
-                    trait_name: t,
-                    args: args,
-                })
-            }
-            None => None
-        };
         AssocTyDefn {
             name: name,
             parameter_kinds: p,
             where_clauses: w,
-            bound,
+            bounds: b.unwrap_or(vec![]),
+        }
+    }
+};
+
+TraitBound: TraitBound = {
+    <t:Id> <a:Angle<Parameter>> => {
+        TraitBound {
+            trait_name: t,
+            args_no_self: a,
         }
     }
 };
@@ -301,6 +299,11 @@ SemiColon<T>: Vec<T> = {
     <Separator<";", T>>
 };
 
+#[inline]
+Plus<T>: Vec<T> = {
+    <Separator<"+", T>>
+};
+
 Angle<T>: Vec<T> = {
     "<" <Comma<T>> ">",
     () => vec![],

src/ir/lowering/test.rs

@@ -311,7 +311,7 @@ fn gat_parse() {
             trait Sized {}
 
             trait Foo {
-                type Item<'a, T>: Clone where Self: Sized;
+                type Item<'a, T>: Sized + Clone where Self: Sized;
             }
 
             trait Bar {