Put slicing syntax behind a feature gate.

[breaking-change]

If you are using slicing syntax you will need to add #![feature(slicing_syntax)] to your crate.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/libsyntax/feature_gate.rs b/src/libsyntax/feature_gate.rs
index ca6d488772c..38de2a9c284 100644
--- a/src/libsyntax/feature_gate.rs
+++ b/src/libsyntax/feature_gate.rs
@@ -70,6 +70,7 @@ static KNOWN_FEATURES: &'static [(&'static str, Status)] = &[
     ("tuple_indexing", Active),
     ("associated_types", Active),
     ("visible_private_types", Active),
+    ("slicing_syntax", Active),
 
     ("if_let", Active),
 
@@ -362,6 +363,11 @@ impl<'a, 'v> Visitor<'v> for Context<'a> {
                 self.gate_feature("if_let", e.span,
                                   "`if let` syntax is experimental");
             }
+            ast::ExprSlice(..) => {
+                self.gate_feature("slicing_syntax",
+                                  e.span,
+                                  "slicing syntax is experimental");
+            }
             _ => {}
         }
         visit::walk_expr(self, e);