Add support for equality constraints on associated types

1 files changed, 16 insertions, 0 deletions

diff --git a/src/libsyntax/ast_util.rs b/src/libsyntax/ast_util.rs
index 7dba6a57fc4..eec3f69ee64 100644
--- a/src/libsyntax/ast_util.rs
+++ b/src/libsyntax/ast_util.rs
@@ -174,12 +174,28 @@ pub fn ident_to_path(s: Span, identifier: Ident) -> Path {
                 parameters: ast::AngleBracketedParameters(ast::AngleBracketedParameterData {
                     lifetimes: Vec::new(),
                     types: OwnedSlice::empty(),
+                    bindings: OwnedSlice::empty(),
                 })
             }
         ),
     }
 }
 
+// If path is a single segment ident path, return that ident. Otherwise, return
+// None.
+pub fn path_to_ident(path: &Path) -> Option<Ident> {
+    if path.segments.len() != 1 {
+        return None;
+    }
+
+    let segment = &path.segments[0];
+    if !segment.parameters.is_empty() {
+        return None;
+    }
+
+    Some(segment.identifier)
+}
+
 pub fn ident_to_pat(id: NodeId, s: Span, i: Ident) -> P<Pat> {
     P(Pat {
         id: id,