Add `box_patterns` feature gate.

Switch feature-gate checker from `box_syntax` to `box_patterns` when
visiting a pattern.

(Having to opt into both `box_syntax` and `box_patterns` seemed
unnecessary.)

[breaking-change]

diff --git a/src/libsyntax/feature_gate.rs b/src/libsyntax/feature_gate.rs
index 72bbe1adfaa123730558b895fdcadad0d63ccc0e..07d331d25bee7d2fccc3e0e52dac8f1a7c16a620 100644 (file)
--- a/src/libsyntax/feature_gate.rs
+++ b/src/libsyntax/feature_gate.rs
@@ -126,6 +126,9 @@
 
     // Allows using #![no_std]
     ("no_std", "1.0.0", Active),
+
+    // Allows using `box` in patterns; RFC 469
+    ("box_patterns", "1.0.0", Active),
 ];
 
 enum Status {
@@ -486,7 +489,7 @@ fn visit_pat(&mut self, pattern: &ast::Pat) {
                                    `[0, ..xs, 0]` are experimental")
             }
             ast::PatBox(..) => {
-                self.gate_feature("box_syntax",
+                self.gate_feature("box_patterns",
                                   pattern.span,
                                   "box pattern syntax is experimental in alpha release");
             }