Built-in Natural literals in Core

Add support for built-in Natural literals in Core.

- Replace MachInt,MachWord, LitInteger, etc. with a single LitNumber
  constructor with a LitNumType field
- Support built-in Natural literals
- Add desugar warning for negative literals
- Move Maybe(..) from GHC.Base to GHC.Maybe for module dependency
  reasons

This patch introduces only a few rules for Natural literals (compared
to Integer's rules). Factorization of the built-in rules for numeric
literals will be done in another patch as this one is already big to
review.

Test Plan:
  validate
  test build with integer-simple

Reviewers: hvr, bgamari, goldfire, Bodigrim, simonmar

Reviewed By: bgamari

Subscribers: phadej, simonpj, RyanGlScott, carter, hsyl20, rwbarton,
thomie

GHC Trac Issues: #14170, #14465

Differential Revision: https://phabricator.haskell.org/D4212

1 files changed, 1 insertions, 0 deletions

diff --git a/libraries/base/GHC/Stack/Types.hs b/libraries/base/GHC/Stack/Types.hs
index d40342c9de..4c8a106ae5 100644
--- a/libraries/base/GHC/Stack/Types.hs
+++ b/libraries/base/GHC/Stack/Types.hs
@@ -53,6 +53,7 @@ import GHC.Types (Char, Int)
 -- Make implicit dependency known to build system
 import GHC.Tuple ()
 import GHC.Integer ()
+import GHC.Natural ()
 
 ----------------------------------------------------------------------
 -- Explicit call-stacks built via ImplicitParams