Auto merge of #21019 - nikomatsakis:issue-20871-ret-as-assoc-type, r=nrc

Fixes https://github.com/rust-lang/rust/issues/20871

r? @aturon (at least until we decide definitively if this is a good idea)

3 files changed, 12 insertions, 3 deletions

diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index 4f6cd8ad356..4dada5bc81e 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -347,6 +347,9 @@ impl AngleBracketedParameterData {
 /// A path like `Foo(A,B) -> C`
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Show)]
 pub struct ParenthesizedParameterData {
+    /// Overall span
+    pub span: Span,
+
     /// `(A,B)`
     pub inputs: Vec<P<Ty>>,
 
diff --git a/src/libsyntax/fold.rs b/src/libsyntax/fold.rs
index bf822599a88..a1362f5382c 100644
--- a/src/libsyntax/fold.rs
+++ b/src/libsyntax/fold.rs
@@ -536,9 +536,10 @@ pub fn noop_fold_parenthesized_parameter_data<T: Folder>(data: ParenthesizedPara
                                                          fld: &mut T)
                                                          -> ParenthesizedParameterData
 {
-    let ParenthesizedParameterData { inputs, output } = data;
+    let ParenthesizedParameterData { inputs, output, span } = data;
     ParenthesizedParameterData { inputs: inputs.move_map(|ty| fld.fold_ty(ty)),
-                                 output: output.map(|ty| fld.fold_ty(ty)) }
+                                 output: output.map(|ty| fld.fold_ty(ty)),
+                                 span: fld.new_span(span) }
 }
 
 pub fn noop_fold_local<T: Folder>(l: P<Local>, fld: &mut T) -> P<Local> {
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index fbea265597c..4c1ae532d13 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -1796,6 +1796,8 @@ impl<'a> Parser<'a> {
                     bindings: OwnedSlice::from_vec(bindings),
                 })
             } else if self.eat(&token::OpenDelim(token::Paren)) {
+                let lo = self.last_span.lo;
+
                 let inputs = self.parse_seq_to_end(
                     &token::CloseDelim(token::Paren),
                     seq_sep_trailing_allowed(token::Comma),
@@ -1807,9 +1809,12 @@ impl<'a> Parser<'a> {
                     None
                 };
 
+                let hi = self.last_span.hi;
+
                 ast::ParenthesizedParameters(ast::ParenthesizedParameterData {
+                    span: mk_sp(lo, hi),
                     inputs: inputs,
-                    output: output_ty
+                    output: output_ty,
                 })
             } else {
                 ast::PathParameters::none()