Explicit Specificity

Implementation for Ticket #16393.
Explicit specificity allows users to manually create inferred type variables,
by marking them with braces.
This way, the user determines which variables can be instantiated through
visible type application.

The additional syntax is included in the parser, allowing users to write
braces in type variable binders (type signatures, data constructors etc).
This information is passed along through the renamer and verified in the
type checker.
The AST for type variable binders, data constructors, pattern synonyms,
partial signatures and Template Haskell has been updated to include the
specificity of type variables.

Minor notes:
- Bumps haddock submodule
- Disables pattern match checking in GHC.Iface.Type with GHC 8.8

1 files changed, 3 insertions, 3 deletions

diff --git a/compiler/GHC/Hs/Instances.hs b/compiler/GHC/Hs/Instances.hs
index f30e07a50e..a003a6b885 100644
--- a/compiler/GHC/Hs/Instances.hs
+++ b/compiler/GHC/Hs/Instances.hs
@@ -392,9 +392,9 @@ deriving instance Data (HsPatSigType GhcRn)
 deriving instance Data (HsPatSigType GhcTc)
 
 -- deriving instance (DataIdLR p p) => Data (HsTyVarBndr p)
-deriving instance Data (HsTyVarBndr GhcPs)
-deriving instance Data (HsTyVarBndr GhcRn)
-deriving instance Data (HsTyVarBndr GhcTc)
+deriving instance (Data flag) => Data (HsTyVarBndr flag GhcPs)
+deriving instance (Data flag) => Data (HsTyVarBndr flag GhcRn)
+deriving instance (Data flag) => Data (HsTyVarBndr flag GhcTc)
 
 -- deriving instance (DataIdLR p p) => Data (HsType p)
 deriving instance Data (HsType GhcPs)