Loading interface files
\begin{code}
+{-# OPTIONS -w #-}
+-- The above warning supression flag is a temporary kludge.
+-- While working on this module you are encouraged to remove it and fix
+-- any warnings in the module. See
+-- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
+-- for details
+
module LoadIface (
loadInterface, loadInterfaceForName, loadWiredInHomeIface,
loadSrcInterface, loadSysInterface, loadOrphanModules,
#include "HsVersions.h"
import {-# SOURCE #-} TcIface( tcIfaceDecl, tcIfaceRules, tcIfaceInst,
- tcIfaceFamInst )
+ tcIfaceFamInst, tcIfaceVectInfo )
import DynFlags
import IfaceSyn
import FamInstEnv
import Name
import NameEnv
-import NameSet
import MkId
import Module
import OccName
import BinIface
import Panic
-import Control.Monad (when)
import Data.List
import Data.Maybe
import Data.IORef
-- | An 'IfM' function to load the home interface for a wired-in thing,
-- so that we're sure that we see its instance declarations and rules
+-- See Note [Loading instances]
loadWiredInHomeIface :: Name -> IfM lcl ()
loadWiredInHomeIface name
= ASSERT( isWiredInName name )
Succeeded iface -> return iface }
\end{code}
+Note [Loading instances]
+~~~~~~~~~~~~~~~~~~~~~~~~
+We need to make sure that we have at least *read* the interface files
+for any module with an instance decl or RULE that we might want.
+
+* If the instance decl is an orphan, we have a whole separate mechanism
+ (loadOprhanModules)
+
+* If the instance decl not an orphan, then the act of looking at the
+ TyCon or Class will force in the defining module for the
+ TyCon/Class, and hence the instance decl
+
+* BUT, if the TyCon is a wired-in TyCon, we don't really need its interface;
+ but we must make sure we read its interface in case it has instances or
+ rules. That is what LoadIface.loadWiredInHomeInterface does. It's called
+ from TcIface.{tcImportDecl, checkWiredInTyCon, ifCHeckWiredInThing}
+
+All of this is done by the type checker. The renamer plays no role.
+(It used to, but no longer.)
+
+
%*********************************************************
%* *
; new_eps_insts <- mapM tcIfaceInst (mi_insts iface)
; new_eps_fam_insts <- mapM tcIfaceFamInst (mi_fam_insts iface)
; new_eps_rules <- tcIfaceRules ignore_prags (mi_rules iface)
+ ; new_eps_vect_info <- tcIfaceVectInfo mod (mkNameEnv new_eps_decls)
+ (mi_vect_info iface)
; let { final_iface = iface {
mi_decls = panic "No mi_decls in PIT",
mi_fam_insts = panic "No mi_fam_insts in PIT",
mi_rules = panic "No mi_rules in PIT"
}
- ; new_eps_vect_info =
- VectInfo {
- vectInfoCCVar = mkNameSet
- (ifaceVectInfoCCVar . mi_vect_info $ iface)
- }
}
; updateEps_ $ \ eps ->
badDepMsg mod
= hang (ptext SLIT("Interface file inconsistency:"))
- 2 (sep [ptext SLIT("home-package module") <+> quotes (ppr mod) <+> ptext SLIT("is mentioned is needed,"),
- ptext SLIT("but is not among the dependencies of interfaces directly imported by the module being compiled")])
+ 2 (sep [ptext SLIT("home-package module") <+> quotes (ppr mod) <+> ptext SLIT("is needed,"),
+ ptext SLIT("but is not listed in the dependencies of the interfaces directly imported by the module being compiled")])
-----------------------------------------------------
-- Loading type/class/value decls
loadDecl ignore_prags mod (_version, decl)
= do { -- Populate the name cache with final versions of all
-- the names associated with the decl
- main_name <- mk_new_bndr mod (ifName decl)
+ main_name <- lookupOrig mod (ifName decl)
-- ; traceIf (text "Loading decl for " <> ppr main_name)
- ; implicit_names <- mapM (mk_new_bndr mod) (ifaceDeclSubBndrs decl)
+ ; implicit_names <- mapM (lookupOrig mod) (ifaceDeclSubBndrs decl)
-- Typecheck the thing, lazily
-- NB. Firstly, the laziness is there in case we never need the
; thing <- forkM doc $ do { bumpDeclStats main_name
; tcIfaceDecl ignore_prags decl }
- -- Populate the type environment with the implicitTyThings too.
- --
- -- Note [Tricky iface loop]
- -- ~~~~~~~~~~~~~~~~~~~~~~~~
- -- The delicate point here is that 'mini-env' should be
- -- buildable from 'thing' without demanding any of the things 'forkM'd
- -- by tcIfaceDecl. For example
- -- class C a where { data T a; op :: T a -> Int }
- -- We return the bindings
- -- [("C", <cls>), ("T", lookup env "T"), ("op", lookup env "op")]
- -- The call (lookup env "T") must return the tycon T without first demanding
- -- op; because getting the latter will look up T, hence loop.
- --
- -- Of course, there is no reason in principle why (lookup env "T") should demand
- -- anything do to with op, but take care:
- -- (a) implicitTyThings, and
- -- (b) getOccName of all the things returned by implicitThings,
- -- must not depend on any of the nested type-checks
- --
- -- All a bit too finely-balanced for my liking.
-
+ -- Populate the type environment with the implicitTyThings too.
+ --
+ -- Note [Tricky iface loop]
+ -- ~~~~~~~~~~~~~~~~~~~~~~~~
+ -- Summary: The delicate point here is that 'mini-env' must be
+ -- buildable from 'thing' without demanding any of the things
+ -- 'forkM'd by tcIfaceDecl.
+ --
+ -- In more detail: Consider the example
+ -- data T a = MkT { x :: T a }
+ -- The implicitTyThings of T are: [ <datacon MkT>, <selector x>]
+ -- (plus their workers, wrappers, coercions etc etc)
+ --
+ -- We want to return an environment
+ -- [ "MkT" -> <datacon MkT>, "x" -> <selector x>, ... ]
+ -- (where the "MkT" is the *Name* associated with MkT, etc.)
+ --
+ -- We do this by mapping the implict_names to the associated
+ -- TyThings. By the invariant on ifaceDeclSubBndrs and
+ -- implicitTyThings, we can use getOccName on the implicit
+ -- TyThings to make this association: each Name's OccName should
+ -- be the OccName of exactly one implictTyThing. So the key is
+ -- to define a "mini-env"
+ --
+ -- [ 'MkT' -> <datacon MkT>, 'x' -> <selector x>, ... ]
+ -- where the 'MkT' here is the *OccName* associated with MkT.
+ --
+ -- However, there is a subtlety: due to how type checking needs
+ -- to be staged, we can't poke on the forkM'd thunks inside the
+ -- implictTyThings while building this mini-env.
+ -- If we poke these thunks too early, two problems could happen:
+ -- (1) When processing mutually recursive modules across
+ -- hs-boot boundaries, poking too early will do the
+ -- type-checking before the recursive knot has been tied,
+ -- so things will be type-checked in the wrong
+ -- environment, and necessary variables won't be in
+ -- scope.
+ --
+ -- (2) Looking up one OccName in the mini_env will cause
+ -- others to be looked up, which might cause that
+ -- original one to be looked up again, and hence loop.
+ --
+ -- The code below works because of the following invariant:
+ -- getOccName on a TyThing does not force the suspended type
+ -- checks in order to extract the name. For example, we don't
+ -- poke on the "T a" type of <selector x> on the way to
+ -- extracting <selector x>'s OccName. Of course, there is no
+ -- reason in principle why getting the OccName should force the
+ -- thunks, but this means we need to be careful in
+ -- implicitTyThings and its helper functions.
+ --
+ -- All a bit too finely-balanced for my liking.
+
+ -- This mini-env and lookup function mediates between the
+ -- *Name*s n and the map from *OccName*s to the implicit TyThings
; let mini_env = mkOccEnv [(getOccName t, t) | t <- implicitTyThings thing]
lookup n = case lookupOccEnv mini_env (getOccName n) of
Just thing -> thing
Nothing ->
pprPanic "loadDecl" (ppr main_name <+> ppr n $$ ppr (decl))
- ; returnM $ (main_name, thing) : [(n, lookup n) | n <- implicit_names]
+ ; returnM $ (main_name, thing) :
+ -- uses the invariant that implicit_names and
+ -- implictTyThings are bijective
+ [(n, lookup n) | n <- implicit_names]
}
- -- We build a list from the *known* names, with (lookup n) thunks
- -- as the TyThings. That way we can extend the PTE without poking the
- -- thunks
where
- -- mk_new_bndr allocates in the name cache the final canonical
- -- name for the thing, with the correct
- -- * parent
- -- * location
- -- imported name, to fix the module correctly in the cache
- mk_new_bndr mod occ
- = newGlobalBinder mod occ
- (importedSrcLoc (showSDoc (ppr (moduleName mod))))
- -- ToDo: qualify with the package name if necessary
-
doc = ptext SLIT("Declaration for") <+> ppr (ifName decl)
bumpDeclStats :: Name -> IfL () -- Record that one more declaration has actually been used
<+> ppr (mi_mod_vers iface) <+> pp_sub_vers
<+> (if mi_orphan iface then ptext SLIT("[orphan module]") else empty)
<+> (if mi_finsts iface then ptext SLIT("[family instance module]") else empty)
+ <+> (if mi_hpc iface then ptext SLIT("[hpc]") else empty)
<+> integer opt_HiVersion
<+> ptext SLIT("where")
, vcat (map pprExport (mi_exports iface))
, vcat (map ppr (mi_insts iface))
, vcat (map ppr (mi_fam_insts iface))
, vcat (map ppr (mi_rules iface))
+ , pprVectInfo (mi_vect_info iface)
, pprDeprecs (mi_deprecs iface)
- ]
+ ]
where
pp_boot | mi_boot iface = ptext SLIT("[boot]")
| otherwise = empty
where
pprFix (occ,fix) = ppr fix <+> ppr occ
+pprVectInfo :: IfaceVectInfo -> SDoc
+pprVectInfo (IfaceVectInfo { ifaceVectInfoVar = vars
+ , ifaceVectInfoTyCon = tycons
+ , ifaceVectInfoTyConReuse = tyconsReuse
+ }) =
+ vcat
+ [ ptext SLIT("vectorised variables:") <+> hsep (map ppr vars)
+ , ptext SLIT("vectorised tycons:") <+> hsep (map ppr tycons)
+ , ptext SLIT("vectorised reused tycons:") <+> hsep (map ppr tyconsReuse)
+ ]
+
pprDeprecs NoDeprecs = empty
pprDeprecs (DeprecAll txt) = ptext SLIT("Deprecate all") <+> doubleQuotes (ftext txt)
pprDeprecs (DeprecSome prs) = ptext SLIT("Deprecate") <+> vcat (map pprDeprec prs)