<div dir="ltr"><pre style="color:rgb(0,0,0);word-wrap:break-word;white-space:pre-wrap">I just saw the error below in a validate with -DDEBUG.  Anyone know about this?</pre><pre style="color:rgb(0,0,0);word-wrap:break-word;white-space:pre-wrap">--- /tmp/ghctest-uhJ8rt/test   spaces/./indexed-types/should_fail/T12041.run/T12041.stderr.normalised 2016-11-09 12:13:38.206501840 +0000
+++ /tmp/ghctest-uhJ8rt/test   spaces/./indexed-types/should_fail/T12041.run/T12041.comp.stderr.normalised      2016-11-09 12:13:38.206501840 +0000
@@ -1,7 +1,17 @@
+ghc: panic! (the 'impossible' happened)
+  (GHC version 8.1.20161109 for x86_64-unknown-linux):
+       ASSERT failed!
+  i_axb
+  Call stack:
+      CallStack (from HasCallStack):
+        prettyCurrentCallStack, called at compiler/utils/Outputable.hs:<line>:<column> in <package-id>:Outputable
+        callStackDoc, called at compiler/utils/Outputable.hs:<line>:<column> in <package-id>:Outputable
+        assertPprPanic, called at compiler/typecheck/TcType.hs:<line>:<column> in <package-id>:TcType
+  Call stack:
+      CallStack (from HasCallStack):
+        prettyCurrentCallStack, called at compiler/utils/Outputable.hs:<line>:<column> in <package-id>:Outputable
+        callStackDoc, called at compiler/utils/Outputable.hs:<line>:<column> in <package-id>:Outputable
+        pprPanic, called at compiler/utils/Outputable.hs:<line>:<column> in <package-id>:Outputable
+        assertPprPanic, called at compiler/typecheck/TcType.hs:<line>:<column> in <package-id>:TcType
 
-T12041.hs:12:15:
-     Expected kind â€˜i -> Constraint’,
-        but â€˜(~) Int’ has kind â€˜* -> Constraint’
-     In the type â€˜(~) Int’
-      In the type instance declaration for â€˜Ob’
-      In the instance declaration for â€˜Category I’
+Please report this as a GHC bug:  <a href="http://www.haskell.org/ghc/reportabug">http://www.haskell.org/ghc/reportabug</a>
*** unexpected failure for T12041(normal)</pre></div>