Syntax: Support dyn traits.

cc rust-lang#284

Author: ehuss

RustEnhanced.sublime-syntax

@@ -437,6 +437,8 @@ contexts:
           __m(?:64|128|256)[di]? # __m512 should come later
         )\b
       scope: storage.type.rust
+    - match: '\bdyn\b(?!\s*::)(?=\s*(?:\(|''?{{identifier}}))'
+      scope: storage.type.trait.rust
 
   generic-angles:
     - meta_scope: meta.generic.rust

syntax_test_rust.rs

@@ -1442,3 +1442,47 @@ struct S (
 //              ^ meta.struct punctuation.definition.group.end
 //                ^^^ meta.struct storage.type
 );
+
+// dyn trait
+fn f(x: dyn T, y: Box<dyn T + 'static>, z: &dyn T,
+//      ^^^ meta.function.parameters storage.type.trait
+//                    ^^^ meta.function.parameters meta.generic storage.type.trait
+//                                          ^^^ meta.function.parameters storage.type.trait
+     f: &dyn Fn(CrateNum) -> bool) -> dyn T {
+//       ^^^ meta.function.parameters storage.type.trait
+//                                    ^^^ meta.function.return-type storage.type.trait
+    let x: &(dyn 'static + Display) = &BYTE;
+//           ^^^ meta.group storage.type.trait
+    let y: Box<dyn Display + 'static> = Box::new(BYTE);
+//             ^^^ meta.generic storage.type.trait
+    let _: &dyn (Display) = &BYTE;
+//          ^^^ storage.type.trait
+    let _: &dyn (::std::fmt::Display) = &BYTE;
+//          ^^^ storage.type.trait
+    const DT: &'static dyn C = &V;
+//                     ^^^ storage.type.trait
+    struct S {
+        f: dyn T
+//         ^^^ meta.struct storage.type.trait
+    }
+    type D4 = dyn (::module::Trait);
+//            ^^^ storage.type.trait
+}
+
+// dyn is not a keyword in all situations (a "weak" keyword).
+type A0 = dyn;
+//        ^^^ -storage.type.trait
+type A1 = dyn::dyn;
+//        ^^^^^ meta.path -storage.type.trait
+//             ^^^ -storage.type.trait
+type A2 = dyn<dyn, dyn>;
+//        ^^^ meta.generic -storage.type.trait
+//            ^^^ meta.generic -storage.type.trait
+//                 ^^^ meta.generic -storage.type.trait
+// This is incorrect.  `identifier` should not match on the keyword `as`.
+// However, avoiding keywords is a little complicated and slow.
+type A3 = dyn<<dyn as dyn>::dyn>;
+//        ^^^ meta.generic -storage.type.trait
+//             ^^^ meta.generic storage.type.trait
+//                    ^^^ meta.generic -storage.type.trait
+//                          ^^^ meta.generic -storage.type.trait