---

yaml
---
r: 219294
b: refs/heads/snap-stage3
c: 34d5b54
h: refs/heads/master
v: v3

Author: Marwes

[refs]

@@ -1,6 +1,6 @@
 ---
 refs/heads/master: c044791d80ea0dc5c4b57b6030a67b69f8510239
-refs/heads/snap-stage3: 7721d46bd76967e73a04b7944651094d3d2f9274
+refs/heads/snap-stage3: 34d5b5450cf8728321a77f3e32393197fd66a325
 refs/heads/try: b53c0f93eedcdedd4fd89bccc5a3a09d1c5cd23e
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/tags/release-0.2: c870d2dffb391e14efb05aa27898f1f6333a9596

branches/snap-stage3/src/libsyntax/ext/deriving/generic/mod.rs

@@ -1042,10 +1042,12 @@ impl<'a> MethodDef<'a> {
     /// variants where all of the variants match, and one catch-all for
     /// when one does not match.
 
+    /// As an optimization we generate code which checks whether all variants
+    /// match first which makes llvm see that C-like enums can be compiled into
+    /// a simple equality check (for PartialEq).
+
     /// The catch-all handler is provided access the variant index values
-    /// for each of the self-args, carried in precomputed variables. (Nota
-    /// bene: the variant index values are not necessarily the
-    /// discriminant values.  See issue #15523.)
+    /// for each of the self-args, carried in precomputed variables.
 
     /// ```{.text}
     /// let __self0_vi = unsafe {