Obsolete Sized? T

[breaking-change]

Use `T: ?Sized`

Author: nrc

src/libsyntax/parse/obsolete.rs

@@ -22,6 +22,7 @@ use ptr::P;
 /// The specific types of unsupported syntax
 #[derive(Copy, PartialEq, Eq, Hash)]
 pub enum ObsoleteSyntax {
+    Sized,
     OwnedType,
     OwnedExpr,
     OwnedPattern,
@@ -92,7 +93,11 @@ impl<'a> ParserObsoleteMethods for parser::Parser<'a> {
             ObsoleteSyntax::ExternCrateRenaming => (
                 "`extern crate foo = bar` syntax",
                 "write `extern crate bar as foo` instead"
-            )
+            ),
+            ObsoleteSyntax::Sized => (
+                "`Sized? T` syntax for removing the `Sized` bound",
+                "write `T: ?Sized` instead"
+            ),
         };
 
         self.report(sp, kind, kind_str, desc);

src/libsyntax/parse/parser.rs

@@ -4092,8 +4092,8 @@ impl<'a> Parser<'a> {
         // unbound, and it may only be `Sized`. To avoid backtracking and other
         // complications, we parse an ident, then check for `?`. If we find it,
         // we use the ident as the unbound, otherwise, we use it as the name of
-        // type param. Even worse, for now, we need to check for `?` before or
-        // after the bound.
+        // type param. Even worse, we need to check for `?` before or after the
+        // bound.
         let mut span = self.span;
         let mut ident = self.parse_ident();
         let mut unbound = None;
@@ -4102,6 +4102,7 @@ impl<'a> Parser<'a> {
             unbound = Some(tref);
             span = self.span;
             ident = self.parse_ident();
+            self.obsolete(span, ObsoleteSyntax::Sized);
         }
 
         let mut bounds = self.parse_colon_then_ty_param_bounds(BoundParsingMode::Modified);