3 files changed, 14 insertions, 4 deletions
diff --git a/src/libsyntax/ext/quote.rs b/src/libsyntax/ext/quote.rs
index e46bd7ac4bc..f1b52fa33c3 100644
--- a/src/libsyntax/ext/quote.rs
+++ b/src/libsyntax/ext/quote.rs
@@ -85,14 +85,14 @@ pub mod rt {
     */
 
     // FIXME: Move this trait to pprust and get rid of *_to_str?
-    pub trait ToSource for Sized? {
+    pub trait ToSource {
         // Takes a thing and generates a string containing rust code for it.
         fn to_source(&self) -> String;
     }
 
     // FIXME (Issue #16472): This should go away after ToToken impls
     // are revised to go directly to token-trees.
-    trait ToSourceWithHygiene for Sized? : ToSource {
+    trait ToSourceWithHygiene : ToSource {
         // Takes a thing and generates a string containing rust code
         // for it, encoding Idents as special byte sequences to
         // maintain hygiene across serialization and deserialization.
diff --git a/src/libsyntax/parse/obsolete.rs b/src/libsyntax/parse/obsolete.rs
index 75b2c17b81b..f4606a4e6da 100644
--- a/src/libsyntax/parse/obsolete.rs
+++ b/src/libsyntax/parse/obsolete.rs
@@ -24,6 +24,7 @@ use ptr::P;
 /// The specific types of unsupported syntax
 #[derive(Copy, PartialEq, Eq, Hash)]
 pub enum ObsoleteSyntax {
+    ObsoleteForSized,
     ObsoleteOwnedType,
     ObsoleteOwnedExpr,
     ObsoleteOwnedPattern,
@@ -56,6 +57,11 @@ impl<'a> ParserObsoleteMethods for parser::Parser<'a> {
     /// Reports an obsolete syntax non-fatal error.
     fn obsolete(&mut self, sp: Span, kind: ObsoleteSyntax) {
         let (kind_str, desc) = match kind {
+            ObsoleteForSized => (
+                "for Sized?",
+                "no longer required. Traits (and their `Self` type) do not have the `Sized` bound \
+                 by default",
+            ),
             ObsoleteProcType => (
                 "the `proc` type",
                 "use unboxed closures instead",
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 9b3df744317..2eb77489c6e 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -5052,6 +5052,7 @@ impl<'a> Parser<'a> {
         // re-jigged shortly in any case, so leaving the hacky version for now.
         if self.eat_keyword(keywords::For) {
             let span = self.span;
+
             let mut ate_question = false;
             if self.eat(&token::Question) {
                 ate_question = true;
@@ -5069,8 +5070,11 @@ impl<'a> Parser<'a> {
                     "expected `?Sized` after `for` in trait item");
                 return None;
             }
-            let tref = Parser::trait_ref_from_ident(ident, span);
-            Some(tref)
+            let _tref = Parser::trait_ref_from_ident(ident, span);
+
+            self.obsolete(span, ObsoleteForSized);
+
+            None
         } else {
             None
         }