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{-# LANGUAGE ScopedTypeVariables #-}
{-
(c) The University of Glasgow 2006
(c) The GRASP/AQUA Project, Glasgow University, 1993-1998
A ``lint'' pass to check for Core correctness.
See Note [Core Lint guarantee].
-}
module GHC.Core.Lint.Interactive (
interactiveInScope,
) where
import GHC.Prelude
import GHC.Runtime.Context
import GHC.Core.Coercion
import GHC.Core.TyCo.FVs
import GHC.Core.InstEnv ( instanceDFunId, instEnvElts )
import GHC.Types.Id
import GHC.Types.TypeEnv
interactiveInScope :: InteractiveContext -> [Var]
-- In GHCi we may lint expressions, or bindings arising from 'deriving'
-- clauses, that mention variables bound in the interactive context.
-- These are Local things (see Note [Interactively-bound Ids in GHCi] in GHC.Runtime.Context).
-- So we have to tell Lint about them, lest it reports them as out of scope.
--
-- We do this by find local-named things that may appear free in interactive
-- context. This function is pretty revolting and quite possibly not quite right.
-- When we are not in GHCi, the interactive context (hsc_IC hsc_env) is empty
-- so this is a (cheap) no-op.
--
-- See #8215 for an example
interactiveInScope ictxt
= tyvars ++ ids
where
-- C.f. GHC.Tc.Module.setInteractiveContext, Desugar.deSugarExpr
(cls_insts, _fam_insts) = ic_instances ictxt
te1 = mkTypeEnvWithImplicits (ic_tythings ictxt)
te = extendTypeEnvWithIds te1 (map instanceDFunId $ instEnvElts cls_insts)
ids = typeEnvIds te
tyvars = tyCoVarsOfTypesList $ map idType ids
-- Why the type variables? How can the top level envt have free tyvars?
-- I think it's because of the GHCi debugger, which can bind variables
-- f :: [t] -> [t]
-- where t is a RuntimeUnk (see TcType)
|
