Commit b27560c4 authored by simonpj's avatar simonpj
Browse files

[project @ 2002-01-31 17:48:26 by simonpj]

Wibbles to yesterdays changes
parent fb18dd5a
......@@ -5,7 +5,7 @@
\begin{code}
module TcInstDcls ( tcInstDecls1, tcIfaceInstDecls1, addInstDFuns,
tcInstDecls2, tcAddDeclCtxt ) where
tcInstDecls2, initInstEnv, tcAddDeclCtxt ) where
#include "HsVersions.h"
......@@ -44,7 +44,8 @@ import PprType ( pprClassPred )
import TcMonoType ( tcHsTyVars, kcHsSigType, tcHsType, tcHsSigType )
import TcUnify ( checkSigTyVars )
import TcSimplify ( tcSimplifyCheck )
import HscTypes ( HomeSymbolTable, DFunId, PersistentCompilerState(..),
import HscTypes ( HomeSymbolTable, DFunId,
PersistentCompilerState(..), PersistentRenamerState,
ModDetails(..), PackageInstEnv
)
import Subst ( substTy, substTheta )
......@@ -160,9 +161,8 @@ Gather up the instance declarations from their various sources
\begin{code}
tcInstDecls1 -- Deal with source-code instance decls
:: PersistentCompilerState
-> HomeSymbolTable -- Contains instances
-> TcEnv -- Contains IdInfo for dfun ids
:: PersistentRenamerState
-> InstEnv -- Imported instance envt
-> (Name -> Maybe Fixity) -- for deriving Show and Read
-> Module -- Module for deriving
-> [RenamedTyClDecl] -- For deriving stuff
......@@ -172,63 +172,52 @@ tcInstDecls1 -- Deal with source-code instance decls
-- for this module
RenamedHsBinds) -- derived instances
tcInstDecls1 pcs hst unf_env get_fixity
this_mod tycl_decls inst_decls
= let
pkg_inst_env = pcs_insts pcs
prs = pcs_PRS pcs
clas_decls = filter isClassDecl tycl_decls
in
tcInstDecls1 prs inst_env get_fixity this_mod
tycl_decls inst_decls
-- The incoming inst_env includes all the imported instances already
= checkNoErrsTc $
-- Stop if addInstInfos etc discovers any errors
-- (they recover, so that we get more than one error each round)
-- (1) Do the ordinary instance declarations
mapNF_Tc tcLocalInstDecl1 inst_decls `thenNF_Tc` \ local_inst_infos ->
let
local_inst_info = catMaybes local_inst_infos
clas_decls = filter isClassDecl tycl_decls
in
-- (2) Instances from generic class declarations
getGenericInstances clas_decls `thenTc` \ generic_inst_info ->
-- Next, construct the instance environment so far, consisting of
-- a) cached non-home-package InstEnv (gotten from pcs) inst_env0
-- b) imported instance decls (not in the home package) inst_env1
-- c) other modules in this package (gotten from hst) inst_env2
-- d) imported instance decls (from this module) inst_env3
-- e) local instance decls inst_env4
-- f) generic instances inst_env5
-- The result of (b) replaces the cached InstEnv in the PCS
--
-- Note that iface_dfuns may contain not only insts that we
-- demand-loaded from interface files, but also instances from
-- the current module in the case where we are loading this
-- module's interface file in GHCi, so we partition the
-- iface_dfuns into non-local and local instances so that we
-- don't end up with home package instances in the PCS.
--
-- There can't be any instance declarations from the home
-- package other than from the current module (with the
-- compilation manager) because they are loaded explicitly by
-- the compilation manager.
let
local_inst_info = catMaybes local_inst_infos
hst_dfuns = foldModuleEnv ((++) . md_insts) [] hst
in
-- pprTrace "tcInstDecls" (vcat [ppr imported_dfuns, ppr hst_dfuns]) $
addInstDFuns pkg_inst_env hst_dfuns `thenNF_Tc` \ inst_env2 ->
addInstInfos inst_env2 local_inst_info `thenNF_Tc` \ inst_env3 ->
addInstInfos inst_env3 generic_inst_info `thenNF_Tc` \ inst_env4 ->
-- a) imported instance decls (from this module) inst_env1
-- b) local instance decls inst_env2
-- c) generic instances final_inst_env
addInstInfos inst_env local_inst_info `thenNF_Tc` \ inst_env1 ->
addInstInfos inst_env1 generic_inst_info `thenNF_Tc` \ inst_env2 ->
-- (3) Compute instances from "deriving" clauses;
-- note that we only do derivings for things in this module;
-- we ignore deriving decls from interfaces!
-- This stuff computes a context for the derived instance decl, so it
-- needs to know about all the instances possible; hence inst_env4
tcDeriving prs this_mod inst_env4
tcDeriving prs this_mod inst_env2
get_fixity tycl_decls `thenTc` \ (deriv_inst_info, deriv_binds) ->
addInstInfos inst_env4 deriv_inst_info `thenNF_Tc` \ final_inst_env ->
addInstInfos inst_env2 deriv_inst_info `thenNF_Tc` \ final_inst_env ->
returnTc (final_inst_env,
generic_inst_info ++ deriv_inst_info ++ local_inst_info,
deriv_binds)
initInstEnv :: PersistentCompilerState -> HomeSymbolTable -> NF_TcM InstEnv
-- Initialise the instance environment from the
-- persistent compiler state and the home symbol table
initInstEnv pcs hst
= let
pkg_inst_env = pcs_insts pcs
hst_dfuns = foldModuleEnv ((++) . md_insts) [] hst
in
addInstDFuns pkg_inst_env hst_dfuns
addInstInfos :: InstEnv -> [InstInfo] -> NF_TcM InstEnv
addInstInfos inst_env infos = addInstDFuns inst_env (map iDFunId infos)
......
......@@ -52,7 +52,7 @@ import TcEnv ( TcEnv, RecTcEnv, InstInfo(iDFunId), tcExtendGlobalValEnv, tcLook
import TcRules ( tcIfaceRules, tcSourceRules )
import TcForeign ( tcForeignImports, tcForeignExports )
import TcIfaceSig ( tcInterfaceSigs )
import TcInstDcls ( tcInstDecls1, tcIfaceInstDecls1, addInstDFuns, tcInstDecls2 )
import TcInstDcls ( tcInstDecls1, tcIfaceInstDecls1, addInstDFuns, initInstEnv, tcInstDecls2 )
import TcUnify ( unifyTauTy )
import TcSimplify ( tcSimplifyTop, tcSimplifyInfer )
import TcTyClsDecls ( tcTyAndClassDecls )
......@@ -111,7 +111,7 @@ typecheckStmt dflags pcs hst ic_type_env unqual this_mod names (stmt, iface_decl
tcSetDefaultTys defaultDefaultTys $
-- Typecheck the extra declarations
tcExtraDecls pcs this_mod iface_decls `thenTc` \ (new_pcs, env) ->
tcExtraDecls pcs hst this_mod iface_decls `thenTc` \ (new_pcs, env) ->
tcSetEnv env $
tcExtendGlobalTypeEnv ic_type_env $
......@@ -245,7 +245,7 @@ typecheckExpr dflags pcs hst ic_type_env unqual this_mod (expr, decls)
tcSetDefaultTys defaultDefaultTys $
-- Typecheck the extra declarations
tcExtraDecls pcs this_mod decls `thenTc` \ (new_pcs, env) ->
tcExtraDecls pcs hst this_mod decls `thenTc` \ (new_pcs, env) ->
-- Now typecheck the expression
tcSetEnv env $
......@@ -296,15 +296,17 @@ typecheckExtraDecls
typecheckExtraDecls dflags pcs hst unqual this_mod decls
= typecheck dflags pcs hst unqual $
tcExtraDecls pcs this_mod decls `thenTc` \ (new_pcs, _) ->
tcExtraDecls pcs hst this_mod decls `thenTc` \ (new_pcs, _) ->
returnTc new_pcs
tcExtraDecls :: PersistentCompilerState
-> HomeSymbolTable
-> Module
-> [RenamedHsDecl]
-> TcM (PersistentCompilerState, TcEnv)
-- Returned environment includes instances
tcExtraDecls pcs this_mod decls
tcExtraDecls pcs hst this_mod decls
= tcIfaceImports this_mod decls `thenTc` \ (env, all_things, dfuns, rules) ->
addInstDFuns (pcs_insts pcs) dfuns `thenNF_Tc` \ new_pcs_insts ->
let
......@@ -317,8 +319,11 @@ tcExtraDecls pcs this_mod decls
pcs_rules = new_pcs_rules
}
in
-- Add the new instances
tcSetEnv env (tcSetInstEnv new_pcs_insts tcGetEnv) `thenNF_Tc` \ new_env ->
-- Initialise the instance environment
tcSetEnv env (
initInstEnv new_pcs hst `thenNF_Tc` \ inst_env ->
tcSetInstEnv inst_env tcGetEnv
) `thenNF_Tc` \ new_env ->
returnTc (new_pcs, new_env)
\end{code}
......@@ -386,10 +391,11 @@ tcModule pcs hst get_fixity this_mod decls
tcSetEnv env1 $
-- Do the source-language instances, including derivings
tcInstDecls1 new_pcs hst unf_env
initInstEnv new_pcs hst `thenNF_Tc` \ inst_env1 ->
tcInstDecls1 (pcs_PRS new_pcs) inst_env1
get_fixity this_mod
tycl_decls src_inst_decls `thenTc` \ (inst_env, inst_info, deriv_binds) ->
tcSetInstEnv inst_env $
tycl_decls src_inst_decls `thenTc` \ (inst_env2, inst_info, deriv_binds) ->
tcSetInstEnv inst_env2 $
-- Foreign import declarations next
traceTc (text "Tc4") `thenNF_Tc_`
......
......@@ -1738,7 +1738,6 @@ tcSimplifyDeriv tyvars theta
simpleReduceLoop doc reduceMe wanteds `thenTc` \ (frees, _, irreds) ->
ASSERT( null frees ) -- reduceMe never returns Free
doptsTc Opt_AllowUndecidableInstances `thenNF_Tc` \ undecidable_ok ->
let
tv_set = mkVarSet tvs
simpl_theta = map dictPred irreds -- reduceMe squashes all non-dicts
......@@ -1746,8 +1745,11 @@ tcSimplifyDeriv tyvars theta
check_pred pred
-- Check that the returned dictionaries are all of form (C a b)
-- (where a, b are type variables).
-- Unless we have -fallow-undecidable-instances.
| not undecidable_ok && not (isTyVarClassPred pred)
-- At one time we allowed this if we had -fallow-undecidable-instances,
-- but that risks non-termination in the 'deriving' context-inference
-- fixpoint loop. If you want fancy stuff you just have to write the
-- instance decl yourself.
| not (isTyVarClassPred pred)
= addErrTc (noInstErr pred)
-- Check for a bizarre corner case, when the derived instance decl should
......
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