Implement the proposed -XQualifiedDo extension

Co-authored-by: Facundo Domínguez <facundo.dominguez@tweag.io>

QualifiedDo is implemented using the same placeholders for operation names in
the AST that were devised for RebindableSyntax. Whenever the renamer checks
which names to use for do syntax, it first checks if the do block is qualified
(e.g. M.do { stmts }), in which case it searches for qualified names in
the module M.

This allows users to write

    {-# LANGUAGE QualifiedDo #-}
    import qualified SomeModule as M

    f x = M.do           -- desugars to:
      y <- M.return x    -- M.return x M.>>= \y ->
      M.return y         -- M.return y M.>>
      M.return y         -- M.return y

See Note [QualifiedDo] and the users' guide for more details.

Issue #18214

Proposal:
https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0216-qualified-do.rst

Since we change the constructors `ITdo` and `ITmdo` to carry the new module
name, we need to bump the haddock submodule to account or the new shape of
these constructors.

1 files changed, 8 insertions, 0 deletions

diff --git a/compiler/GHC/Hs/Instances.hs b/compiler/GHC/Hs/Instances.hs
index c66488e770..87ded0d22d 100644
--- a/compiler/GHC/Hs/Instances.hs
+++ b/compiler/GHC/Hs/Instances.hs
@@ -315,6 +315,14 @@ deriving instance Data (ApplicativeArg GhcPs)
 deriving instance Data (ApplicativeArg GhcRn)
 deriving instance Data (ApplicativeArg GhcTc)
 
+deriving instance Data (HsStmtContext GhcPs)
+deriving instance Data (HsStmtContext GhcRn)
+deriving instance Data (HsStmtContext GhcTc)
+
+deriving instance Data (HsMatchContext GhcPs)
+deriving instance Data (HsMatchContext GhcRn)
+deriving instance Data (HsMatchContext GhcTc)
+
 -- deriving instance (DataIdLR p p) => Data (HsSplice p)
 deriving instance Data (HsSplice GhcPs)
 deriving instance Data (HsSplice GhcRn)