From de37fa8f002eccea37b0c2ef1c1ef7ba606aff87 Mon Sep 17 00:00:00 2001
From: KAMADA Ken'ichi <kamada@nanohz.org>
Date: Wed, 14 Dec 2016 22:08:51 +0900
Subject: [PATCH] Test if a constant variable can be used in the match arm.

---
 src/tag.rs | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/src/tag.rs b/src/tag.rs
index 66e75e4..2a5bdc1 100644
--- a/src/tag.rs
+++ b/src/tag.rs
@@ -306,3 +306,24 @@ generate_well_known_tag_constants!(
 
     (InteroperabilityIndex, 0x1, "Interoperability identification"),
 );
+
+#[cfg(test)]
+mod tests {
+    use tag;
+    use super::*;
+
+    // This test checks if Tag constants can be used in patterns.
+    #[test]
+    fn tag_constant_in_pattern() {
+        // Destructuring, which will always work.
+        match Tag(Context::Tiff, 0x132) {
+            Tag(Context::Tiff, 0x132) => {},
+            _ => panic!("failed to match Tag"),
+        }
+        // Matching against a constant.  Test if this compiles.
+        match Tag(Context::Tiff, 0x132) {
+            tag::DateTime => {},
+            _ => panic!("failed to match Tag"),
+        }
+    }
+}