idris: patch 0.9.14 to workaround a bug

pkgs/development/compilers/idris/default.nix

@@ -26,6 +26,7 @@ cabal.mkDerivation (self: {
   buildTools = [ happy ];
   extraLibraries = [ boehmgc gmp ];
   configureFlags = "-fllvm -fgmp -fffi";
+  patches = [ ./trifecta-fix.patch ];
   meta = {
     homepage = "http://www.idris-lang.org/";
     description = "Functional Programming Language with Dependent Types";

pkgs/development/compilers/idris/trifecta-fix.patch

@@ -0,0 +1,15 @@
+diff --git a/src/Idris/AbsSyntaxTree.hs b/src/Idris/AbsSyntaxTree.hs
+index 76df969..076f1ff 100644
+--- a/src/Idris/AbsSyntaxTree.hs
++++ b/src/Idris/AbsSyntaxTree.hs
+@@ -194,6 +194,10 @@ data IState = IState {
+     idris_callswho :: Maybe (M.Map Name [Name])
+    }
+
++-- Required for parsers library, and therefore trifecta
++instance Show IState where
++  show = const "{internal state}"
++
+ data SizeChange = Smaller | Same | Bigger | Unknown
+     deriving (Show, Eq)
+ {-!