#15367: Misleading error message when unboxed tuples used in sums without -XUnboxedTuples -------------------------------------+------------------------------------- Reporter: osa1 | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.4.3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{ $ cat lib.hs {-# LANGUAGE UnboxedSums #-} module Lib where type Foo = (# (# Int, Int #) | Int #) $ ghc lib.hs [1 of 1] Compiling Lib ( lib.hs, lib.o ) lib.hs:5:1: error: • Illegal unboxed tuple type as function argument: (# Int, Int #) • In the type synonym declaration for ‘Foo’ | 5 | type Foo = (# (# Int, Int #) | Int #) | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ }}} But there's nothing illegal about this type, we just need to enable `UnboxedTuples`. The error message is misleading. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15367 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler