Output better debug infromation on internal error in extractDecl

This will make investigation of haskell#979 easier
watashi · Dec 13, 2018 · c62ade2 · c62ade2
1 parent d66a17f
commit c62ade2
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/haddock-api/src/Haddock/Interface/Create.hs b/haddock-api/src/Haddock/Interface/Create.hs
@@ -1112,7 +1112,9 @@ extractDecl declMap name decl
             in case matches of
               [d0] -> extractDecl declMap name (noLoc . InstD noExt $ DataFamInstD noExt d0)
               _ -> error "internal: extractDecl (ClsInstD)"
-      _ -> error "internal: extractDecl"
+      _ -> O.pprPanic "extractDecl" $
+        O.text "Unhandled decl for" O.<+> O.ppr name O.<> O.text ":"
+        O.$$ O.nest 4 (O.ppr decl)
 
 
 extractPatternSyn :: Name -> Name -> [LHsType GhcRn] -> [LConDecl GhcRn] -> LSig GhcRn