ghc-9.14.1: GHC/Iface/Recomp.hs
{-# LANGUAGE DeriveFunctor #-}
{-# LANGUAGE MultiWayIf #-}
{-# LANGUAGE TupleSections #-}
{-# LANGUAGE LambdaCase #-}
-- | Module for detecting if recompilation is required
module GHC.Iface.Recomp
( checkOldIface
, RecompileRequired(..)
, needsRecompileBecause
, recompThen
, MaybeValidated(..)
, outOfDateItemBecause
, RecompReason (..)
, CompileReason(..)
, recompileRequired
, addFingerprints
, mkSelfRecomp
)
where
import GHC.Prelude
import GHC.Data.FastString
import GHC.Driver.Backend
import GHC.Driver.Env
import GHC.Driver.DynFlags
import GHC.Driver.Ppr
import GHC.Driver.Plugins
import GHC.Iface.Syntax
import GHC.Iface.Recomp.Binary
import GHC.Iface.Recomp.Types
import GHC.Iface.Load
import GHC.Iface.Recomp.Flags
import GHC.Iface.Env
import GHC.Core
import GHC.Tc.Utils.Monad
import GHC.Hs
import GHC.Data.Graph.Directed
import GHC.Data.Maybe
import GHC.Utils.Error
import GHC.Utils.Panic
import GHC.Utils.Outputable as Outputable
import GHC.Utils.Misc as Utils
import GHC.Utils.Binary
import GHC.Utils.Fingerprint
import GHC.Utils.Exception
import GHC.Utils.Logger
import GHC.Utils.Constants (debugIsOn)
import GHC.Types.Annotations
import GHC.Types.Avail
import GHC.Types.Basic ( ImportLevel(..) )
import GHC.Types.Name
import GHC.Types.Name.Env
import GHC.Types.Name.Set
import GHC.Types.SrcLoc
import GHC.Types.Unique.Set
import GHC.Types.Fixity.Env
import GHC.Types.Unique.Map
import GHC.Unit.External
import GHC.Unit.Finder
import GHC.Unit.State
import GHC.Unit.Home
import GHC.Unit.Module
import GHC.Unit.Module.ModIface
import GHC.Unit.Module.ModSummary
import GHC.Unit.Module.Warnings
import GHC.Unit.Module.Deps
import Control.Monad
import Control.Monad.Trans.State
import Data.List (sortBy, sort, sortOn)
import qualified Data.Map as Map
import qualified Data.Set as Set
import Data.Word (Word64)
import Data.Either
--Qualified import so we can define a Semigroup instance
-- but it doesn't clash with Outputable.<>
import qualified Data.Semigroup
import GHC.List (uncons)
import Data.Ord
import Data.Containers.ListUtils
import GHC.Iface.Errors.Ppr
import Data.Functor
import Data.Bifunctor (first)
import GHC.Types.PkgQual
{-
-----------------------------------------------
Recompilation checking
-----------------------------------------------
A complete description of how recompilation checking works can be
found in the wiki commentary:
https://gitlab.haskell.org/ghc/ghc/wikis/commentary/compiler/recompilation-avoidance
Please read the above page for a top-down description of how this all
works. Notes below cover specific issues related to the implementation.
Basic idea:
* In the mi_usages information in an interface, we record the
fingerprint of each free variable of the module
* In mkIface, we compute the fingerprint of each exported thing A.f.
For each external thing that A.f refers to, we include the fingerprint
of the external reference when computing the fingerprint of A.f. So
if anything that A.f depends on changes, then A.f's fingerprint will
change.
Also record any dependent files added with
* addDependentFile
* #include
* -optP-include
* In checkOldIface we compare the mi_usages for the module with
the actual fingerprint for all each thing recorded in mi_usages
-}
data RecompileRequired
-- | everything is up to date, recompilation is not required
= UpToDate
-- | Need to compile the module
| NeedsRecompile !CompileReason
deriving (Eq)
needsRecompileBecause :: RecompReason -> RecompileRequired
needsRecompileBecause = NeedsRecompile . RecompBecause
data MaybeValidated a
-- | The item contained is validated to be up to date
= UpToDateItem a
-- | The item is are absent altogether or out of date, for the reason given.
| OutOfDateItem
!CompileReason
-- ^ the reason we need to recompile.
(Maybe a)
-- ^ The old item, if it exists
deriving (Functor)
instance Outputable a => Outputable (MaybeValidated a) where
ppr (UpToDateItem a) = text "UpToDate" <+> ppr a
ppr (OutOfDateItem r _) = text "OutOfDate: " <+> ppr r
outOfDateItemBecause :: RecompReason -> Maybe a -> MaybeValidated a
outOfDateItemBecause reason item = OutOfDateItem (RecompBecause reason) item
data CompileReason
-- | The .hs file has been touched, or the .o/.hi file does not exist
= MustCompile
-- | The .o/.hi files are up to date, but something else has changed
-- to force recompilation; the String says what (one-line summary)
| RecompBecause !RecompReason
deriving (Eq)
instance Outputable RecompileRequired where
ppr UpToDate = text "UpToDate"
ppr (NeedsRecompile reason) = ppr reason
instance Outputable CompileReason where
ppr MustCompile = text "MustCompile"
ppr (RecompBecause r) = text "RecompBecause" <+> ppr r
instance Semigroup RecompileRequired where
UpToDate <> r = r
mc <> _ = mc
instance Monoid RecompileRequired where
mempty = UpToDate
data RecompReason
= UnitDepRemoved (ImportLevel, UnitId)
| ModulePackageChanged FastString
| SourceFileChanged
| NoSelfRecompInfo
| ThisUnitIdChanged
| ImpurePlugin
| PluginsChanged
| PluginFingerprintChanged
| ModuleInstChanged
| HieMissing
| HieOutdated
| SigsMergeChanged
| ModuleChanged ModuleName
| ModuleRemoved (ImportLevel, UnitId, ModuleName)
| ModuleAdded (ImportLevel, UnitId, ModuleName)
| ModuleChangedRaw ModuleName
| ModuleChangedIface ModuleName
| FileChanged FilePath
| CustomReason String
| FlagsChanged
| LinkFlagsChanged
| OptimFlagsChanged
| HpcFlagsChanged
| MissingBytecode
| MissingObjectFile
| MissingDynObjectFile
| MissingDynHiFile
| MismatchedDynHiFile
| ObjectsChanged
| LibraryChanged
| THWithJS
deriving (Eq)
instance Outputable RecompReason where
ppr = \case
UnitDepRemoved (_lvl, uid) -> ppr uid <+> text "removed"
ModulePackageChanged s -> ftext s <+> text "package changed"
SourceFileChanged -> text "Source file changed"
NoSelfRecompInfo -> text "Old interface lacks recompilation info"
ThisUnitIdChanged -> text "-this-unit-id changed"
ImpurePlugin -> text "Impure plugin forced recompilation"
PluginsChanged -> text "Plugins changed"
PluginFingerprintChanged -> text "Plugin fingerprint changed"
ModuleInstChanged -> text "Implementing module changed"
HieMissing -> text "HIE file is missing"
HieOutdated -> text "HIE file is out of date"
SigsMergeChanged -> text "Signatures to merge in changed"
ModuleChanged m -> ppr m <+> text "changed"
ModuleChangedRaw m -> ppr m <+> text "changed (raw)"
ModuleChangedIface m -> ppr m <+> text "changed (interface)"
ModuleRemoved (_st, _uid, m) -> ppr m <+> text "removed"
ModuleAdded (_st, _uid, m) -> ppr m <+> text "added"
FileChanged fp -> text fp <+> text "changed"
CustomReason s -> text s
FlagsChanged -> text "Flags changed"
LinkFlagsChanged -> text "Flags changed"
OptimFlagsChanged -> text "Optimisation flags changed"
HpcFlagsChanged -> text "HPC flags changed"
MissingBytecode -> text "Missing bytecode"
MissingObjectFile -> text "Missing object file"
MissingDynObjectFile -> text "Missing dynamic object file"
MissingDynHiFile -> text "Missing dynamic interface file"
MismatchedDynHiFile -> text "Mismatched dynamic interface file"
ObjectsChanged -> text "Objects changed"
LibraryChanged -> text "Library changed"
THWithJS -> text "JS backend always recompiles modules using Template Haskell for now (#23013)"
recompileRequired :: RecompileRequired -> Bool
recompileRequired UpToDate = False
recompileRequired _ = True
recompThen :: Monad m => m RecompileRequired -> m RecompileRequired -> m RecompileRequired
recompThen ma mb = ma >>= \case
UpToDate -> mb
rr@(NeedsRecompile _) -> pure rr
checkList :: Monad m => [m RecompileRequired] -> m RecompileRequired
checkList = \case
[] -> return UpToDate
(check : checks) -> check `recompThen` checkList checks
----------------------
-- | Top level function to check if the version of an old interface file
-- is equivalent to the current source file the user asked us to compile.
-- If the same, we can avoid recompilation.
--
-- We return on the outside whether the interface file is up to date, providing
-- evidence that is with a `ModIface`. In the case that it isn't, we may also
-- return a found or provided `ModIface`. Why we don't always return the old
-- one, if it exists, is unclear to me, except that I tried it and some tests
-- failed (see #18205).
checkOldIface
:: HscEnv
-> ModSummary
-> Maybe ModIface -- Old interface from compilation manager, if any
-> IO (MaybeValidated ModIface)
checkOldIface hsc_env mod_summary maybe_iface
= do let dflags = hsc_dflags hsc_env
let logger = hsc_logger hsc_env
showPass logger $
"Checking old interface for " ++
(showPpr dflags $ ms_mod mod_summary) ++
" (use -ddump-hi-diffs for more details)"
initIfaceCheck (text "checkOldIface") hsc_env $
check_old_iface hsc_env mod_summary maybe_iface
check_old_iface
:: HscEnv
-> ModSummary
-> Maybe ModIface
-> IfG (MaybeValidated ModIface)
check_old_iface hsc_env mod_summary maybe_iface
= let dflags = hsc_dflags hsc_env
logger = hsc_logger hsc_env
getIface =
case maybe_iface of
Just {} -> do
trace_if logger (text "We already have the old interface for" <+>
ppr (ms_mod mod_summary))
return maybe_iface
Nothing -> loadIface dflags (msHiFilePath mod_summary)
loadIface read_dflags iface_path = do
let ncu = hsc_NC hsc_env
read_result <- readIface (hsc_hooks hsc_env) logger read_dflags ncu (ms_mod mod_summary) iface_path
case read_result of
Failed err -> do
let msg = readInterfaceErrorDiagnostic err
trace_if logger
$ vcat [ text "FYI: cannot read old interface file:"
, nest 4 msg ]
trace_hi_diffs logger $
vcat [ text "Old interface file was invalid:"
, nest 4 msg ]
return Nothing
Succeeded iface -> do
trace_if logger (text "Read the interface file" <+> text iface_path)
return $ Just iface
check_dyn_hi :: ModIface
-> IfG (MaybeValidated ModIface)
-> IfG (MaybeValidated ModIface)
check_dyn_hi normal_iface recomp_check | gopt Opt_BuildDynamicToo dflags = do
res <- recomp_check
case res of
UpToDateItem _ -> do
maybe_dyn_iface <- liftIO $ loadIface (setDynamicNow dflags) (msDynHiFilePath mod_summary)
case maybe_dyn_iface of
Nothing -> return $ outOfDateItemBecause MissingDynHiFile Nothing
Just dyn_iface | mi_iface_hash dyn_iface
/= mi_iface_hash normal_iface
-> return $ outOfDateItemBecause MismatchedDynHiFile Nothing
Just {} -> return res
_ -> return res
check_dyn_hi _ recomp_check = recomp_check
src_changed
| gopt Opt_ForceRecomp dflags = True
| otherwise = False
in do
when src_changed $
liftIO $ trace_hi_diffs logger (nest 4 $ text "Recompilation check turned off")
case src_changed of
-- If the source has changed and we're in interactive mode,
-- avoid reading an interface; just return the one we might
-- have been supplied with.
True | not (backendWritesFiles $ backend dflags) ->
return $ OutOfDateItem MustCompile maybe_iface
-- Try and read the old interface for the current module
-- from the .hi file left from the last time we compiled it
True -> do
maybe_iface' <- liftIO $ getIface
return $ OutOfDateItem MustCompile maybe_iface'
False -> do
maybe_iface' <- liftIO $ getIface
case maybe_iface' of
-- We can't retrieve the iface
Nothing -> return $ OutOfDateItem MustCompile Nothing
-- We have got the old iface; check its versions
-- even in the SourceUnmodifiedAndStable case we
-- should check versions because some packages
-- might have changed or gone away.
Just iface ->
case mi_self_recomp_info iface of
Nothing -> return $ outOfDateItemBecause NoSelfRecompInfo Nothing
Just sr_info -> check_dyn_hi iface $ checkVersions hsc_env mod_summary iface sr_info
-- | Check if a module is still the same 'version'.
--
-- This function is called in the recompilation checker after we have
-- determined that the module M being checked hasn't had any changes
-- to its source file since we last compiled M. So at this point in general
-- two things may have changed that mean we should recompile M:
-- * The interface export by a dependency of M has changed.
-- * The compiler flags specified this time for M have changed
-- in a manner that is significant for recompilation.
-- We return not just if we should recompile the object file but also
-- if we should rebuild the interface file.
checkVersions :: HscEnv
-> ModSummary
-> ModIface -- Old interface
-> IfaceSelfRecomp
-> IfG (MaybeValidated ModIface)
checkVersions hsc_env mod_summary iface self_recomp
= do { liftIO $ trace_hi_diffs logger
(text "Considering whether compilation is required for" <+>
ppr (mi_module iface) <> colon)
-- readIface will have verified that the UnitId matches,
-- but we ALSO must make sure the instantiation matches up. See
-- test case bkpcabal04!
; hsc_env <- getTopEnv
; if mi_sr_src_hash self_recomp /= ms_hs_hash mod_summary
then return $ outOfDateItemBecause SourceFileChanged Nothing else do {
; if not (isHomeModule home_unit (mi_module iface))
then return $ outOfDateItemBecause ThisUnitIdChanged Nothing else do {
; recomp <- liftIO $ checkFlagHash hsc_env (mi_module iface) self_recomp
`recompThen` checkOptimHash hsc_env self_recomp
`recompThen` checkHpcHash hsc_env self_recomp
`recompThen` checkMergedSignatures hsc_env mod_summary self_recomp
`recompThen` checkHsig logger home_unit mod_summary iface
`recompThen` pure (checkHie dflags mod_summary)
; case recomp of (NeedsRecompile reason) -> return $ OutOfDateItem reason Nothing ; _ -> do {
; recomp <- checkDependencies hsc_env mod_summary iface
; case recomp of (NeedsRecompile reason) -> return $ OutOfDateItem reason (Just iface) ; _ -> do {
; recomp <- checkPlugins (hsc_plugins hsc_env) self_recomp
; case recomp of (NeedsRecompile reason) -> return $ OutOfDateItem reason Nothing ; _ -> do {
-- Source code unchanged and no errors yet... carry on
--
-- First put the dependent-module info, read from the old
-- interface, into the envt, so that when we look for
-- interfaces we look for the right one (.hi or .hi-boot)
--
-- It's just temporary because either the usage check will succeed
-- (in which case we are done with this module) or it'll fail (in which
-- case we'll compile the module from scratch anyhow).
when (isOneShot (ghcMode (hsc_dflags hsc_env))) $ do {
; updateEps_ $ \eps -> eps { eps_is_boot = mkModDeps $ dep_boot_mods (mi_deps iface) }
}
; recomp <- checkList [checkModUsage (hsc_FC hsc_env) u
| u <- mi_sr_usages self_recomp]
; case recomp of (NeedsRecompile reason) -> return $ OutOfDateItem reason (Just iface) ; _ -> do {
; return $ UpToDateItem iface
}}}}}}}
where
logger = hsc_logger hsc_env
dflags = hsc_dflags hsc_env
home_unit = hsc_home_unit hsc_env
-- | Check if any plugins are requesting recompilation
checkPlugins :: Plugins -> IfaceSelfRecomp -> IfG RecompileRequired
checkPlugins plugins self_recomp = liftIO $ do
recomp <- recompPlugins plugins
let new_fingerprint = fingerprintPluginRecompile recomp
let old_fingerprint = mi_sr_plugin_hash self_recomp
return $ pluginRecompileToRecompileRequired old_fingerprint new_fingerprint recomp
recompPlugins :: Plugins -> IO PluginRecompile
recompPlugins plugins = mconcat <$> mapM pluginRecompile' (pluginsWithArgs plugins)
fingerprintPlugins :: Plugins -> IO Fingerprint
fingerprintPlugins plugins = fingerprintPluginRecompile <$> recompPlugins plugins
fingerprintPluginRecompile :: PluginRecompile -> Fingerprint
fingerprintPluginRecompile recomp = case recomp of
NoForceRecompile -> fingerprintString "NoForceRecompile"
ForceRecompile -> fingerprintString "ForceRecompile"
-- is the chance of collision worth worrying about?
-- An alternative is to fingerprintFingerprints [fingerprintString
-- "maybeRecompile", fp]
MaybeRecompile fp -> fp
pluginRecompileToRecompileRequired
:: Fingerprint -> Fingerprint -> PluginRecompile -> RecompileRequired
pluginRecompileToRecompileRequired old_fp new_fp pr
| old_fp == new_fp =
case pr of
NoForceRecompile -> UpToDate
-- we already checked the fingerprint above so a mismatch is not possible
-- here, remember that: `fingerprint (MaybeRecomp x) == x`.
MaybeRecompile _ -> UpToDate
-- when we have an impure plugin in the stack we have to unconditionally
-- recompile since it might integrate all sorts of crazy IO results into
-- its compilation output.
ForceRecompile -> needsRecompileBecause ImpurePlugin
| old_fp `elem` magic_fingerprints ||
new_fp `elem` magic_fingerprints
-- The fingerprints do not match either the old or new one is a magic
-- fingerprint. This happens when non-pure plugins are added for the first
-- time or when we go from one recompilation strategy to another: (force ->
-- no-force, maybe-recomp -> no-force, no-force -> maybe-recomp etc.)
--
-- For example when we go from ForceRecomp to NoForceRecomp
-- recompilation is triggered since the old impure plugins could have
-- changed the build output which is now back to normal.
= needsRecompileBecause PluginsChanged
| otherwise =
case pr of
-- even though a plugin is forcing recompilation the fingerprint changed
-- which would cause recompilation anyways so we report the fingerprint
-- change instead.
ForceRecompile -> needsRecompileBecause PluginFingerprintChanged
_ -> needsRecompileBecause PluginFingerprintChanged
where
magic_fingerprints =
[ fingerprintString "NoForceRecompile"
, fingerprintString "ForceRecompile"
]
-- | Check if an hsig file needs recompilation because its
-- implementing module has changed.
checkHsig :: Logger -> HomeUnit -> ModSummary -> ModIface -> IO RecompileRequired
checkHsig logger home_unit mod_summary iface = do
let outer_mod = ms_mod mod_summary
inner_mod = homeModuleNameInstantiation home_unit (moduleName outer_mod)
massert (isHomeModule home_unit outer_mod)
case inner_mod == mi_semantic_module iface of
True -> up_to_date logger (text "implementing module unchanged")
False -> return $ needsRecompileBecause ModuleInstChanged
-- | Check if @.hie@ file is out of date or missing.
checkHie :: DynFlags -> ModSummary -> RecompileRequired
checkHie dflags mod_summary =
let hie_date_opt = ms_hie_date mod_summary
hi_date = ms_iface_date mod_summary
in if not (gopt Opt_WriteHie dflags)
then UpToDate
else case (hie_date_opt, hi_date) of
(Nothing, _) -> needsRecompileBecause HieMissing
(Just hie_date, Just hi_date)
| hie_date < hi_date
-> needsRecompileBecause HieOutdated
_ -> UpToDate
-- | Check the flags haven't changed
checkFlagHash :: HscEnv -> Module -> IfaceSelfRecomp -> IO RecompileRequired
checkFlagHash hsc_env iface_mod self_recomp = do
let logger = hsc_logger hsc_env
let FingerprintWithValue old_fp old_flags = mi_sr_flag_hash self_recomp
let (new_fp, new_flags) = fingerprintDynFlags hsc_env iface_mod putNameLiterally
if old_fp == new_fp
then up_to_date logger (text "Module flags unchanged")
else do
-- Do not perform this computation unless -ddump-hi-diffs is on
let diffs = case old_flags of
Nothing -> pure [missingExtraFlagInfo]
Just old_flags -> checkIfaceFlags old_flags new_flags
out_of_date logger FlagsChanged (fmap vcat diffs)
checkIfaceFlags :: IfaceDynFlags -> IfaceDynFlags -> IO [SDoc]
checkIfaceFlags (IfaceDynFlags a1 a2 a3 a4 a5 a6 a7 a8 a9 a10 a11 a12 a13 a14)
(IfaceDynFlags b1 b2 b3 b4 b5 b6 b7 b8 b9 b10 b11 b12 b13 b14) =
flip execStateT [] $ do
check_one "main is" (ppr . fmap (fmap (text @SDoc))) a1 b1
check_one_simple "safemode" a2 b2
check_one_simple "lang" a3 b3
check_one_simple "exts" a4 b4
check_one_simple "cpp option" a5 b5
check_one_simple "js option" a6 b6
check_one_simple "cmm option" a7 b7
check_one "paths" (ppr . map (text @SDoc)) a8 b8
check_one_simple "prof" a9 b9
check_one_simple "ticky" a10 b10
check_one_simple "codegen" a11 b11
check_one_simple "fat iface" a12 b12
check_one_simple "debug level" a13 b13
check_one_simple "caller cc filter" a14 b14
where
diffSimple p a b = vcat [text "before:" <+> p a
, text "after:" <+> p b ]
check_one_simple s a b = check_one s ppr a b
check_one s p a b = do
let a' = computeFingerprint putNameLiterally a
let b' = computeFingerprint putNameLiterally b
if a' == b' then pure () else modify (([ text s <+> text "flags changed"] ++ [diffSimple p a b]) ++)
-- | Check the optimisation flags haven't changed
checkOptimHash :: HscEnv -> IfaceSelfRecomp -> IO RecompileRequired
checkOptimHash hsc_env iface = do
let logger = hsc_logger hsc_env
let old_hash = mi_sr_opt_hash iface
let !new_hash = fingerprintOptFlags (hsc_dflags hsc_env)
putNameLiterally
if | old_hash == new_hash
-> up_to_date logger (text "Optimisation flags unchanged")
| gopt Opt_IgnoreOptimChanges (hsc_dflags hsc_env)
-> up_to_date logger (text "Optimisation flags changed; ignoring")
| otherwise
-> out_of_date_hash logger OptimFlagsChanged
(text " Optimisation flags have changed")
old_hash new_hash
-- | Check the HPC flags haven't changed
checkHpcHash :: HscEnv -> IfaceSelfRecomp -> IO RecompileRequired
checkHpcHash hsc_env self_recomp = do
let logger = hsc_logger hsc_env
let old_hash = mi_sr_hpc_hash self_recomp
let !new_hash = fingerprintHpcFlags (hsc_dflags hsc_env)
putNameLiterally
if | old_hash == new_hash
-> up_to_date logger (text "HPC flags unchanged")
| gopt Opt_IgnoreHpcChanges (hsc_dflags hsc_env)
-> up_to_date logger (text "HPC flags changed; ignoring")
| otherwise
-> out_of_date_hash logger HpcFlagsChanged
(text " HPC flags have changed")
old_hash new_hash
-- Check that the set of signatures we are merging in match.
-- If the -unit-id flags change, this can change too.
checkMergedSignatures :: HscEnv -> ModSummary -> IfaceSelfRecomp -> IO RecompileRequired
checkMergedSignatures hsc_env mod_summary self_recomp = do
let logger = hsc_logger hsc_env
let unit_state = hsc_units hsc_env
let old_merged = sort [ mod | UsageMergedRequirement{ usg_mod = mod } <- mi_sr_usages self_recomp ]
new_merged = case lookupUniqMap (requirementContext unit_state)
(ms_mod_name mod_summary) of
Nothing -> []
Just r -> sort $ map (instModuleToModule unit_state) r
if old_merged == new_merged
then up_to_date logger (text "signatures to merge in unchanged" $$ ppr new_merged)
else return $ needsRecompileBecause SigsMergeChanged
-- If the direct imports of this module are resolved to targets that
-- are not among the dependencies of the previous interface file,
-- then we definitely need to recompile. This catches cases like
-- - an exposed package has been upgraded
-- - we are compiling with different package flags
-- - a home module that was shadowing a package module has been removed
-- - a new home module has been added that shadows a package module
-- See bug #1372.
--
-- Returns (RecompBecause <reason>) if recompilation is required.
checkDependencies :: HscEnv -> ModSummary -> ModIface -> IfG RecompileRequired
checkDependencies hsc_env summary iface
= do
res_normal <- classify_import (findImportedModule hsc_env)
([(st, p, m) | (st, p, m) <- (ms_textual_imps summary)]
++
[(NormalLevel, NoPkgQual, m) | m <- ms_srcimps summary ])
res_plugin <- classify_import (\mod _ -> findPluginModule hsc_env mod)
[(st, p, m) | (st, p, m) <- (ms_plugin_imps summary) ]
case sequence (res_normal ++ res_plugin) of
Left recomp -> return $ NeedsRecompile recomp
Right es -> do
let (hs, ps) = partitionEithers es
liftIO $
check_mods (sort hs) prev_dep_mods
`recompThen`
let allPkgDeps = sortBy (comparing snd) $ nubOrdOn snd ps
in check_packages allPkgDeps prev_dep_pkgs
where
classify_import :: (ModuleName -> t -> IO FindResult)
-> [(ImportLevel, t, GenLocated l ModuleName)]
-> IfG
[Either
CompileReason (Either (ImportLevel, UnitId, ModuleName) (FastString, (ImportLevel, UnitId)))]
classify_import find_import imports =
liftIO $ traverse (\(st, mb_pkg, L _ mod) ->
let reason = ModuleChanged mod
in classify st reason <$> find_import mod mb_pkg)
imports
logger = hsc_logger hsc_env
all_home_units = hsc_all_home_unit_ids hsc_env
prev_dep_mods = map (\(IfaceImportLevel s,u, a) -> (s, u, gwib_mod a)) $ Set.toAscList $ dep_direct_mods (mi_deps iface)
prev_dep_pkgs = Set.toAscList (Set.union (Set.map (first tcImportLevel) (dep_direct_pkgs (mi_deps iface)))
(Set.map ((SpliceLevel),) (dep_plugin_pkgs (mi_deps iface))))
classify st _ (Found _ mod)
| (toUnitId $ moduleUnit mod) `elem` all_home_units = Right (Left ((st, toUnitId $ moduleUnit mod, moduleName mod)))
| otherwise = Right (Right (moduleNameFS (moduleName mod), (st, toUnitId $ moduleUnit mod)))
classify _ reason _ = Left (RecompBecause reason)
check_mods :: [(ImportLevel, UnitId, ModuleName)] -> [(ImportLevel, UnitId, ModuleName)] -> IO RecompileRequired
check_mods [] [] = return UpToDate
check_mods [] (old:_) = do
-- This case can happen when a module is change from HPT to package import
trace_hi_diffs logger $
text "module no longer" <+> quotes (ppr old) <+>
text "in dependencies"
return $ needsRecompileBecause $ ModuleRemoved old
check_mods (new:news) olds
| Just (old, olds') <- uncons olds
, new == old = check_mods (dropWhile (== new) news) olds'
| otherwise = do
trace_hi_diffs logger $
text "imported module " <> quotes (ppr new) <>
text " not among previous dependencies"
return $ needsRecompileBecause $ ModuleAdded new
check_packages :: [(FastString, (ImportLevel, UnitId))] -> [(ImportLevel, UnitId)] -> IO RecompileRequired
check_packages [] [] = return UpToDate
check_packages [] (old:_) = do
trace_hi_diffs logger $
text "package " <> quotes (ppr old) <>
text "no longer in dependencies"
return $ needsRecompileBecause $ UnitDepRemoved old
check_packages ((new_name, (new_unit)):news) olds
| Just (old, olds') <- uncons olds
, new_unit == old = check_packages (dropWhile ((== new_unit) . snd) news) olds'
| otherwise = do
trace_hi_diffs logger $
text "imported package" <+> ftext new_name <+> ppr new_unit <+>
text "not among previous dependencies"
return $ needsRecompileBecause $ ModulePackageChanged new_name
needInterface :: Module -> (ModIface -> IO RecompileRequired)
-> IfG RecompileRequired
needInterface mod continue
= do
mb_recomp <- tryGetModIface
"need version info for"
mod
case mb_recomp of
Nothing -> return $ NeedsRecompile MustCompile
Just iface -> liftIO $ continue iface
tryGetModIface :: String -> Module -> IfG (Maybe ModIface)
tryGetModIface doc_msg mod
= do -- Load the imported interface if possible
logger <- getLogger
let doc_str = sep [text doc_msg, ppr mod]
liftIO $ trace_hi_diffs logger (text "Checking interface for module" <+> ppr mod <+> ppr (moduleUnit mod))
mb_iface <- loadInterface doc_str mod ImportBySystem
-- Load the interface, but don't complain on failure;
-- Instead, get an Either back which we can test
case mb_iface of
Failed _ -> do
liftIO $ trace_hi_diffs logger (sep [text "Couldn't load interface for module", ppr mod])
return Nothing
-- Couldn't find or parse a module mentioned in the
-- old interface file. Don't complain: it might
-- just be that the current module doesn't need that
-- import and it's been deleted
Succeeded iface -> pure $ Just iface
-- | Given the usage information extracted from the old
-- M.hi file for the module being compiled, figure out
-- whether M needs to be recompiled.
checkModUsage :: FinderCache -> Usage -> IfG RecompileRequired
checkModUsage _ UsagePackageModule{
usg_mod = mod,
usg_mod_hash = old_mod_hash } = do
logger <- getLogger
needInterface mod $ \iface -> do
let reason = ModuleChanged (moduleName mod)
checkModuleFingerprint logger reason old_mod_hash (mi_mod_hash iface)
-- We only track the ABI hash of package modules, rather than
-- individual entity usages, so if the ABI hash changes we must
-- recompile. This is safe but may entail more recompilation when
-- a dependent package has changed.
checkModUsage _ UsageMergedRequirement{ usg_mod = mod, usg_mod_hash = old_mod_hash } = do
logger <- getLogger
needInterface mod $ \iface -> do
let reason = ModuleChangedRaw (moduleName mod)
checkModuleFingerprint logger reason old_mod_hash (mi_mod_hash iface)
checkModUsage _ UsageHomeModuleInterface{ usg_mod_name = mod_name
, usg_unit_id = uid
, usg_iface_hash = old_mod_hash } = do
let mod = mkModule (RealUnit (Definite uid)) mod_name
logger <- getLogger
needInterface mod $ \iface -> do
let reason = ModuleChangedIface mod_name
checkIfaceFingerprint logger reason old_mod_hash (mi_iface_hash iface)
checkModUsage _ UsageHomeModule{
usg_mod_name = mod_name,
usg_unit_id = uid,
usg_mod_hash = old_mod_hash,
usg_exports = maybe_imported_exports,
usg_entities = old_decl_hash }
= do
let mod = mkModule (RealUnit (Definite uid)) mod_name
logger <- getLogger
needInterface mod $ \iface -> do
let
new_mod_hash = mi_mod_hash iface
new_decl_hash = mi_hash_fn iface
reason = ModuleChanged (moduleName mod)
liftIO $ do
-- CHECK MODULE
recompile <- checkModuleFingerprint logger reason old_mod_hash new_mod_hash
if not (recompileRequired recompile)
then return UpToDate
else checkList
[ -- CHECK EXPORT LIST; see Note [When to recompile when export lists change?]
checkHomeModImport logger reason maybe_imported_exports iface
, -- CHECK USED ITEMS ONE BY ONE
checkList [ checkEntityUsage logger reason new_decl_hash u
| u <- old_decl_hash]
, up_to_date logger (text " Great! The bits I use are up to date")
]
checkModUsage fc UsageFile{ usg_file_path = file,
usg_file_hash = old_hash,
usg_file_label = mlabel } =
liftIO $
handleIO handler $ do
new_hash <- lookupFileCache fc $ unpackFS file
if (old_hash /= new_hash)
then return recomp
else return UpToDate
where
reason = FileChanged $ unpackFS file
recomp = needsRecompileBecause $ fromMaybe reason $ fmap CustomReason mlabel
handler = if debugIsOn
then \e -> pprTrace "UsageFile" (text (show e)) $ return recomp
else \_ -> return recomp -- if we can't find the file, just recompile, don't fail
-- | We are importing a module whose exports have changed.
-- Does this require recompilation?
--
-- See Note [When to recompile when export lists change?]
checkHomeModImport :: Logger -> RecompReason -> Maybe HomeModImport -> ModIface -> IO RecompileRequired
checkHomeModImport _ _ Nothing _ = return UpToDate
checkHomeModImport logger reason
(Just (HomeModImport old_orphan_like_hash old_avails))
iface
-- (1) Orphans (of the module we are importing or of its dependencies)
-- have changed: recompilation is required.
--
-- See Note [Orphan-like hash].
| old_orphan_like_hash /= new_orphan_like_hash
= out_of_date_hash logger reason (text " Orphan-likes changed")
old_orphan_like_hash new_orphan_like_hash
| otherwise
-- (2) Is there a change in the set of entities we are importing?
= case old_avails of
-- (a) Whole module import: recompile if the export hash
-- of the module we are importing has changed.
HMIA_Implicit old_avails_hash
| old_avails_hash /= new_avails_hash
-> out_of_date_hash logger reason (text " Export list changed")
old_orphan_like_hash new_orphan_like_hash
| otherwise
-> return UpToDate
-- (b) Explicit imports: recompile if there is a change in the
-- set of imported items.
HMIA_Explicit
{ hmia_imported_avails = DetOrdAvails imps
, hmia_parents_with_implicits = parents_of_implicits
} ->
case checkNewExportedAvails new_exports parents_of_implicits imps of
[] -> return UpToDate
changes@(_:_) ->
do trace_hi_diffs logger $
hang (text "Export list changed")
2 (ppr changes)
return $ needsRecompileBecause reason
where
new_orphan_like_hash = mi_orphan_like_hash iface
new_avails_hash = mi_export_avails_hash iface
new_exports = mi_exports iface
-- | The exported avails of a module have changed. Should this cause recompilation
-- of a module that imports it?
--
-- This is only about export/import lists; checking for changes in the definitions
-- of used identifiers is done later (see 'checkEntityUsage').
--
-- See Note [When to recompile when export lists change?].
checkNewExportedAvails :: [AvailInfo] -> NameSet -> [AvailInfo] -> [AvailInfo]
checkNewExportedAvails new_avails parents_of_implicits imported_avails
= concatMap go imported_avails
where
go a@(Avail n) =
case lookupNameEnv env n of
Nothing -> [a]
Just {} -> []
go a@(AvailTC n ns) =
case lookupNameEnv env n of
Nothing -> [a]
Just a' ->
case a' of
Avail {} -> [a]
AvailTC _ ns'
| n `elemNameSet` parents_of_implicits
->
-- We are dealing with an export item of the form @T(..)@.
-- If the set of subordinate names has changed at all, we must
-- recompile.
if mkNameSet ns == mkNameSet ns'
then []
else [a]
| otherwise
->
-- We are dealing with an import item of the form @T(K,x,y)@.
-- Just check that all the names we are explicitly importing
-- continue to be exported. It's OK if T has more children
-- than it used to.
if all (`elem` ns') ns
then []
else [a]
env = availsToNameEnv new_avails
{- Note [When to recompile when export lists change?]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Suppose module N imports module M, and the exports of M change. Does this
require recompiling N?
Suppose for example that we have:
module M (foo) where
foo = 3
module N where
import M
bar = foo + 1
baz = 2 * bar
If we add an identifier to the export list of M, we must recompile N because
this might introduce name clashes, e.g. changing M to:
module M (foo, bar) where
foo = 3
bar = 7
will cause N to no longer compile because of a name clash involving 'bar'.
However, if N had an explicit import list:
module N where
import M(foo)
bar = foo + 1
baz = 2 * bar
then it *does not matter* that 'M' starts exporting 'bar'; 'N' is unaffected.
This justifies the following approach for deciding whether a change in exports
should lead to recompilation.
(1) If the orphan instances exported by M change, or if the orphans of
dependencies of M change, we must recompile N.
See Note [Orphan-like hash]
(2) Otherwise, look at all the import declarations that import M.
(a) If there is a whole module import, or an "import hiding" import,
then we must recompile N when the avails exported from M change
(such a change is detected by using the 'mi_export_avails_hash').
(b) Otherwise, all imports are explicit imports, but not every identifier
is necessarily explicitly imported, as we might have an import of
the form @import M(T(..))@.
We proceed by comparing what we are importing from M against the
new exports of M. We recompile unless the following two conditions
are both satisfied:
C1. Every explicitly imported identifier continues to be exported.
C2. For every parent P in an import item of the form @P(..)@,
the set of subordinates exported by P has not changed.
Note that this import check is done purely on the basis of the Names involved,
unlike the subsequent recompilation check done in 'checkEntityUsage' which
checks that the definitions of used identifiers have not changed.
Note [Orphan-like hash]
~~~~~~~~~~~~~~~~~~~~~~~
The orphan-like hash extends the orphan hash to include other entities that
also cause recompilation downstream upon changing.
The hash includes:
(1) orphan class and family instances
(2) exported named defaults (these are very similar to orphan instances)
(3) non-orphan type family instances, including those of dependencies
(4) the Safe Haskell safety of the module
Why do we need to do this? For (3), suppose we have:
module A where
type instance F Int = Bool
module B where
import A
module C where
import B
The family instance consistency check for C depends on the dep_finsts of
B. If we rename module A to A2, when the dep_finsts of B changes, we need
to make sure that C gets rebuilt. Effectively, the dep_finsts are part of
the exports of B, because C always considers them when checking
consistency.
A full discussion is in #12723.
We do NOT need to hash dep_orphs, because this is implied by
dep_orphan_hashes, and we do not need to hash ordinary (non-orphan) class
instances, because there is no eager consistency check as there is with type
families. For this reason, we don't currently store a hash of non-orphan class
instances.
-}
------------------------
checkModuleFingerprint
:: Logger
-> RecompReason
-> Fingerprint
-> Fingerprint
-> IO RecompileRequired
checkModuleFingerprint logger reason old_mod_hash new_mod_hash
| new_mod_hash == old_mod_hash
= up_to_date logger (text "Module fingerprint unchanged")
| otherwise
= out_of_date_hash logger reason (text " Module fingerprint has changed")
old_mod_hash new_mod_hash
checkIfaceFingerprint
:: Logger
-> RecompReason
-> Fingerprint
-> Fingerprint
-> IO RecompileRequired
checkIfaceFingerprint logger reason old_mod_hash new_mod_hash
| new_mod_hash == old_mod_hash
= up_to_date logger (text "Iface fingerprint unchanged")
| otherwise
= out_of_date_hash logger reason (text " Iface fingerprint has changed")
old_mod_hash new_mod_hash
------------------------
checkEntityUsage :: Logger
-> RecompReason
-> (OccName -> Maybe (OccName, Fingerprint))
-> (OccName, Fingerprint)
-> IO RecompileRequired
checkEntityUsage logger reason new_hash (name,old_hash) = do
case new_hash name of
-- We used it before, but it ain't there now
Nothing -> out_of_date logger reason (pure $ sep [text "No longer exported:", ppr name])
-- It's there, but is it up to date?
Just (_, new_hash)
| new_hash == old_hash
-> do trace_hi_diffs logger (text " Up to date" <+> ppr name <+> parens (ppr new_hash))
return UpToDate
| otherwise
-> out_of_date_hash logger reason (text " Out of date:" <+> ppr name) old_hash new_hash
up_to_date :: Logger -> SDoc -> IO RecompileRequired
up_to_date logger msg = trace_hi_diffs logger msg >> return UpToDate
out_of_date :: Logger -> RecompReason -> IO SDoc -> IO RecompileRequired
out_of_date logger reason msg = trace_hi_diffs_io logger msg >> return (needsRecompileBecause reason)
out_of_date_hash :: Logger -> RecompReason -> SDoc -> Fingerprint -> Fingerprint -> IO RecompileRequired
out_of_date_hash logger reason msg old_hash new_hash
= out_of_date logger reason (pure $ hsep [msg, ppr old_hash, text "->", ppr new_hash])
-- ---------------------------------------------------------------------------
-- Compute fingerprints for the interface
{- Note [Fingerprinting IfaceDecls]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The general idea here is that we first examine the 'IfaceDecl's and determine
the recursive groups of them. We then walk these groups in dependency order,
serializing each contained 'IfaceDecl' to a "Binary" buffer which we then
hash using MD5 to produce a fingerprint for the group.
However, the serialization that we use is a bit funny: we override the @putName@
operation with our own which serializes the hash of a 'Name' instead of the
'Name' itself. This ensures that the fingerprint of a decl changes if anything
in its transitive closure changes. This trick is why we must be careful about
traversing in dependency order: we need to ensure that we have hashes for
everything referenced by the decl which we are fingerprinting.
Moreover, we need to be careful to distinguish between serialization of binding
Names (e.g. the ifName field of a IfaceDecl) and non-binding (e.g. the ifInstCls
field of a IfaceClsInst): only in the non-binding case should we include the
fingerprint; in the binding case we shouldn't since it is merely the name of the
thing that we are currently fingerprinting.
Note [Fingerprinting recursive groups]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The fingerprinting of a single recursive group is a rather subtle affair, as
seen in #18733.
How not to fingerprint
----------------------
Prior to fixing #18733 we used the following (flawed) scheme to fingerprint a
group in hash environment `hash_env0`:
1. extend hash_env0, giving each declaration in the group the fingerprint 0
2. use this environment to hash the declarations' ABIs, resulting in
group_fingerprint
3. produce the final hash environment by extending hash_env0, mapping each
declaration of the group to group_fingerprint
However, this is wrong. Consider, for instance, a program like:
data A = ARecu B | ABase String deriving (Show)
data B = BRecu A | BBase Int deriving (Show)
info :: B
info = BBase 1
A consequence of (3) is that A and B will have the same fingerprint. This means
that if the user changes `info` to:
info :: A
info = ABase "hello"
The program's ABI fingerprint will not change despite `info`'s type, and
therefore ABI, being clearly different.
However, the incorrectness doesn't end there: (1) means that all recursive
occurrences of names within the group will be given the same fingerprint. This
means that the group's fingerprint won't change if we change an occurrence of A
to B.
Surprisingly, this bug (#18733) lurked for many years before being uncovered.
How we now fingerprint
----------------------
As seen above, the fingerprinting function must ensure that a groups
fingerprint captures the structure of within-group occurrences. The scheme that
we use is:
0. To ensure determinism, sort the declarations into a stable order by
declaration name
1. Extend hash_env0, giving each declaration in the group a sequential
fingerprint (e.g. 0, 1, 2, ...).
2. Use this environment to hash the declarations' ABIs, resulting in
group_fingerprint.
Since we included the sequence number in step (1) programs identical up to
transposition of recursive occurrences are distinguishable, avoiding the
second issue mentioned above.
3. Produce the final environment by extending hash_env, mapping each
declaration of the group to the hash of (group_fingerprint, i), where
i is the position of the declaration in the stable ordering.
Including i in the hash ensures that the first issue noted above is
avoided.
-}
-- | Compute the information needed for self-recompilation checking. This
-- information can be computed before the backend phase.
mkSelfRecomp :: HscEnv -> Module -> Fingerprint -> [Usage] -> IO IfaceSelfRecomp
mkSelfRecomp hsc_env this_mod src_hash usages = do
let dflags = hsc_dflags hsc_env
let dyn_flags_info = fingerprintDynFlags hsc_env this_mod putNameLiterally
let opt_hash = fingerprintOptFlags dflags putNameLiterally
let hpc_hash = fingerprintHpcFlags dflags putNameLiterally
plugin_hash <- fingerprintPlugins (hsc_plugins hsc_env)
let include_detailed_flags (flag_hash, flags) =
if gopt Opt_WriteSelfRecompFlags dflags
then FingerprintWithValue flag_hash (Just flags)
else FingerprintWithValue flag_hash Nothing
return (IfaceSelfRecomp
{ mi_sr_flag_hash = include_detailed_flags dyn_flags_info
, mi_sr_hpc_hash = hpc_hash
, mi_sr_opt_hash = opt_hash
, mi_sr_plugin_hash = plugin_hash
, mi_sr_src_hash = src_hash
, mi_sr_usages = usages })
-- | Add fingerprints for top-level declarations to a 'ModIface'.
--
-- See Note [Fingerprinting IfaceDecls]
addFingerprints
:: HscEnv
-> PartialModIface
-> IO ModIface
addFingerprints hsc_env iface0 = do
(abiHashes, caches, decls_w_hashes) <- addAbiHashes hsc_env (mi_mod_info iface0) (mi_public iface0) (mi_deps iface0)
-- put the declarations in a canonical order, sorted by OccName
let sorted_decls :: [(Fingerprint, IfaceDecl)]
sorted_decls = Map.elems $ Map.fromList $
[(getOccName d, e) | e@(_, d) <- decls_w_hashes]
-- This key is safe because mi_extra_decls contains tidied things.
getOcc (IfGblTopBndr b) = getOccName b
getOcc (IfLclTopBndr fs _ _ details) =
case details of
IfRecSelId { ifRecSelFirstCon = first_con }
-> mkRecFieldOccFS (getOccFS first_con) (ifLclNameFS fs)
_ -> mkVarOccFS (ifLclNameFS fs)
binding_key (IfaceNonRec b _) = IfaceNonRec (getOcc b) ()
binding_key (IfaceRec bs) = IfaceRec (map (\(b, _) -> (getOcc b, ())) bs)
sorted_extra_decls :: Maybe IfaceSimplifiedCore
sorted_extra_decls = mi_simplified_core iface0 <&> \simpl_core ->
IfaceSimplifiedCore (sortOn binding_key (mi_sc_extra_decls simpl_core)) (mi_sc_foreign simpl_core)
-- The interface hash depends on:
-- - the ABI hash, plus
-- - the things which can affect whether a module is recompiled
-- - the module level annotations,
-- - deps (home and external packages, dependent files)
let !iface_hash = computeFingerprint putNameLiterally
(mi_abi_mod_hash abiHashes,
mi_self_recomp_info iface0,
mi_deps iface0)
let final_iface = completePartialModIface iface0 iface_hash
sorted_decls sorted_extra_decls abiHashes caches
--
return final_iface
-- The ABI hash should depend on everything in IfacePublic
-- This is however computed in a very convoluted way, so be careful your
-- addition ends up in the right place. In essence all this function does is
-- compute a hash of the arguments.
--
-- Why the convoluted way? Hashing individual declarations allows us to do fine-grained
-- recompilation checking for home package modules, which record precisely what they use
-- from each module.
addAbiHashes :: HscEnv -> IfaceModInfo -> PartialIfacePublic -> Dependencies -> IO (IfaceAbiHashes, IfaceCache, [(Fingerprint, IfaceDecl)])
addAbiHashes hsc_env info
iface_public
deps = do
eps <- hscEPS hsc_env
let
-- If you have arrived here by accident then congratulations,
-- you have discovered the ABI hash. Your reward is to update the ABI hash to
-- account for your change to the interface file. Omitting your field using a
-- wildcard may lead to some unfortunate consequences.
IfacePublic
exports fixities warns anns decls
defaults insts fam_insts rules
trust _trust_pkg -- TODO: trust_pkg ignored
complete
_cache
()
= iface_public
-- And these fields of deps should be in IfacePublic, but in good time.
Dependencies _ _ _ sig_mods trusted_pkgs boot_mods orph_mods fis_mods = deps
decl_warn_fn = mkIfaceDeclWarnCache (fromIfaceWarnings warns)
export_warn_fn = mkIfaceExportWarnCache (fromIfaceWarnings $ warns)
fix_fn = mkIfaceFixCache fixities
this_mod = mi_mod_info_module info
semantic_mod = mi_mod_info_semantic_module info
(non_orph_insts, orph_insts) = mkOrphMap ifInstOrph insts
(non_orph_rules, orph_rules) = mkOrphMap ifRuleOrph rules
(non_orph_fis, orph_fis) = mkOrphMap ifFamInstOrph fam_insts
complete_matches = mkIfaceCompleteMap complete
ann_fn = mkIfaceAnnCache anns
-- The ABI of a declaration represents everything that is made
-- visible about the declaration that a client can depend on.
-- see IfaceDeclABI below.
declABI :: IfaceDecl -> IfaceDeclABI
-- TODO: I'm not sure if this should be semantic_mod or this_mod.
-- See also Note [Identity versus semantic module]
declABI decl = (this_mod, decl, extras)
where extras = declExtras fix_fn ann_fn non_orph_rules non_orph_insts
non_orph_fis top_lvl_name_env complete_matches decl
-- This is used for looking up the Name of a default method
-- from its OccName. See Note [default method Name]
top_lvl_name_env =
mkOccEnv [ (nameOccName nm, nm)
| IfaceId { ifName = nm } <- decls ]
-- Dependency edges between declarations in the current module.
-- This is computed by finding the free external names of each
-- declaration, including IfaceDeclExtras (things that a
-- declaration implicitly depends on).
edges :: [ Node OccName IfaceDeclABI ]
edges = [ DigraphNode abi (getOccName decl) out
| decl <- decls
, let abi = declABI decl
, let out = localOccs $ freeNamesDeclABI abi
]
name_module n = assertPpr (isExternalName n) (ppr n) (nameModule n)
localOccs =
map (getParent . getOccName)
-- NB: names always use semantic module, so
-- filtering must be on the semantic module!
-- See Note [Identity versus semantic module]
. filter ((== semantic_mod) . name_module)
. nonDetEltsUniqSet
-- It's OK to use nonDetEltsUFM as localOccs is only
-- used to construct the edges and
-- stronglyConnCompFromEdgedVertices is deterministic
-- even with non-deterministic order of edges as
-- explained in Note [Deterministic SCC] in GHC.Data.Graph.Directed.
where getParent :: OccName -> OccName
getParent occ = lookupOccEnv parent_map occ `orElse` occ
-- maps OccNames to their parents in the current module.
-- e.g. a reference to a constructor must be turned into a reference
-- to the TyCon for the purposes of calculating dependencies.
parent_map :: OccEnv OccName
parent_map = foldl' extend emptyOccEnv decls
where extend env d =
extendOccEnvList env [ (b,n) | b <- ifaceDeclImplicitBndrs d ]
where n = getOccName d
-- Strongly-connected groups of declarations, in dependency order
groups :: [SCC IfaceDeclABI]
groups = stronglyConnCompFromEdgedVerticesOrd edges
global_hash_fn = mkHashFun hsc_env eps
-- How to output Names when generating the data to fingerprint.
-- Here we want to output the fingerprint for each top-level
-- Name, whether it comes from the current module or another
-- module. In this way, the fingerprint for a declaration will
-- change if the fingerprint for anything it refers to (transitively)
-- changes.
mk_put_name :: OccEnv (OccName,Fingerprint)
-> WriteBinHandle -> Name -> IO ()
mk_put_name local_env bh name
| isWiredInName name = putNameLiterally bh name
-- wired-in names don't have fingerprints
| otherwise
= assertPpr (isExternalName name) (ppr name) $
let hash | nameModule name /= semantic_mod = global_hash_fn name
-- Get it from the REAL interface!!
-- This will trigger when we compile an hsig file
-- and we know a backing impl for it.
-- See Note [Identity versus semantic module]
| semantic_mod /= this_mod
, not (isHoleModule semantic_mod) = global_hash_fn name
| otherwise = return (snd (lookupOccEnv local_env (getOccName name)
`orElse` pprPanic "urk! lookup local fingerprint"
(ppr name $$ ppr local_env)))
-- This panic indicates that we got the dependency
-- analysis wrong, because we needed a fingerprint for
-- an entity that wasn't in the environment. To debug
-- it, turn the panic into a trace, uncomment the
-- pprTraces below, run the compile again, and inspect
-- the output and the generated .hi file with
-- --show-iface.
in hash >>= put_ bh
-- take a strongly-connected group of declarations and compute
-- its fingerprint.
fingerprint_group :: (OccEnv (OccName,Fingerprint),
[(Fingerprint,IfaceDecl)])
-> SCC IfaceDeclABI
-> IO (OccEnv (OccName,Fingerprint),
[(Fingerprint,IfaceDecl)])
fingerprint_group (local_env, decls_w_hashes) (AcyclicSCC abi)
= do let hash_fn = mk_put_name local_env
decl = abiDecl abi
--pprTrace "fingerprinting" (ppr (ifName decl) ) $ do
let !hash = computeFingerprint hash_fn abi
env' <- extend_hash_env local_env (hash,decl)
return (env', (hash,decl) : decls_w_hashes)
fingerprint_group (local_env, decls_w_hashes) (CyclicSCC abis)
= do let stable_abis = sortBy cmp_abiNames abis
stable_decls = map abiDecl stable_abis
local_env1 <- foldM extend_hash_env local_env
(zip (map mkRecFingerprint [0..]) stable_decls)
-- See Note [Fingerprinting recursive groups]
let hash_fn = mk_put_name local_env1
-- pprTrace "fingerprinting" (ppr (map ifName decls) ) $ do
-- put the cycle in a canonical order
let !hash = computeFingerprint hash_fn stable_abis
let pairs = zip (map (bumpFingerprint hash) [0..]) stable_decls
-- See Note [Fingerprinting recursive groups]
local_env2 <- foldM extend_hash_env local_env pairs
return (local_env2, pairs ++ decls_w_hashes)
-- Make a fingerprint from the ordinal position of a binding in its group.
mkRecFingerprint :: Word64 -> Fingerprint
mkRecFingerprint i = Fingerprint 0 i
bumpFingerprint :: Fingerprint -> Word64 -> Fingerprint
bumpFingerprint fp n = fingerprintFingerprints [ fp, mkRecFingerprint n ]
-- we have fingerprinted the whole declaration, but we now need
-- to assign fingerprints to all the OccNames that it binds, to
-- use when referencing those OccNames in later declarations.
--
extend_hash_env :: OccEnv (OccName,Fingerprint)
-> (Fingerprint,IfaceDecl)
-> IO (OccEnv (OccName,Fingerprint))
extend_hash_env env0 (hash,d) =
return (foldr (\(b,fp) env -> extendOccEnv env b (b,fp)) env0
(ifaceDeclFingerprints hash d))
--
(local_env, decls_w_hashes) <-
foldM fingerprint_group (emptyOccEnv, []) groups
-- The export hash of a module depends on the orphan hashes of the
-- orphan modules below us in the dependency tree. This is the way
-- that changes in orphans get propagated all the way up the
-- dependency tree.
--
-- NB: do not filter out non-home-package modules!
-- See Note [Take into account non-home package orphan modules].
let orph_mods_no_self
= filter (/= this_mod) -- Note [Do not update EPS with your own hi-boot]
$ orph_mods
dep_orphan_hashes <- getOrphanHashes hsc_env orph_mods_no_self
let !orphan_hash = computeFingerprint (mk_put_name local_env)
(map ifDFun orph_insts, orph_rules, orph_fis)
-- Hash of the transitive things in dependencies
let !dep_hash = computeFingerprint putNameLiterally
( sig_mods, boot_mods
, trusted_pkgs -- Trusted packages are like orphans
, fis_mods -- See Note [Orphan-like hash]
)
-- The export list hash doesn't depend on the fingerprints of
-- the Names it mentions, only the Names themselves, hence putNameLiterally.
--
-- As per Note [When to recompile when export lists change?], there are two
-- separate considerations:
--
-- (1) If there is a change in exported orphan instances, we must recompile.
--
-- In fact, we must include slightly more items here than only the orphan
-- instances defined in the current module; see Note [Orphan-like hash].
--
-- (2) If there is a change in the exported avails, this may or may not
-- require recompilation downstream, depending on what is imported.
-- In the case that the downstream module has a whole module import,
-- then we recompile when any exports change, by looking at export_hash.
let
-- (1) Orphan-like information, see Note [Orphan-like hash].
!orphan_like_hash =
computeFingerprint putNameLiterally
( orphan_hash, dep_hash, dep_orphan_hashes
, defaults -- Changes in exported named defaults cause recompilation
, trust -- Change of Safe Haskell mode causes recompilation
)
-- (2) Exported avails
!exported_avails_hash = computeFingerprint putNameLiterally exports
-- the ABI hash depends on:
-- - decls
-- - export list
-- - orphans
-- - deprecations
-- - flag abi hash
let !mod_hash = computeFingerprint putNameLiterally
(sort (map fst decls_w_hashes),
exported_avails_hash,
orphan_like_hash, -- includes orphan_hash
ann_fn AnnModule,
warns)
-- Surely the ABI depends on "module" annotations?
-- Also named defaults
let
final_iface_exts = IfaceAbiHashes
{ mi_abi_mod_hash = mod_hash
, mi_abi_orphan = not ( all ifRuleAuto orph_rules
-- See Note [Orphans and auto-generated rules]
&& null orph_insts
&& null orph_fis)
, mi_abi_finsts = not (null fam_insts)
, mi_abi_export_avails_hash = exported_avails_hash
, mi_abi_orphan_like_hash = orphan_like_hash
, mi_abi_orphan_hash = orphan_hash
}
caches = IfaceCache
{ mi_cache_decl_warn_fn = decl_warn_fn
, mi_cache_export_warn_fn = export_warn_fn
, mi_cache_fix_fn = fix_fn
, mi_cache_hash_fn = lookupOccEnv local_env
}
return (final_iface_exts, caches, decls_w_hashes)
where
{- Note [Take into account non-home package orphan modules]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We need to take into account all orphan modules, not just those that are from
the home package.
Historically, we filtered out orphan modules which were not from the home
package, justifying it by saying that "we'd pick up the ABI hashes of the
external module instead". This is wrong.
Suppose that we have:
module External where
instance Show (a -> b)
module Home1 where
import External
module Home2 where
import Home1
The export hash of Home1 needs to reflect the orphan instances of
External. It's true that Home1 will get rebuilt if the orphans
of External, but we also need to make sure Home2 gets rebuilt
as well. See #12733 for more details.
Note [Do not update EPS with your own hi-boot]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When your hs-boot file includes an orphan instance declaration, you may find
that the dep_orphs of a module you import contains reference to yourself.
DO NOT actually load this module or add it to the orphan hashes: you're going
to provide the orphan instances yourself, no need to consult hs-boot; if you do
load the interface into EPS, you will see a duplicate orphan instance.
See also #10182.
-}
-- | Retrieve the orphan hashes 'mi_orphan_hash' for a list of modules
-- (in particular, the orphan modules which are transitively imported by the
-- current module).
--
-- Q: Why do we need the hash at all, doesn't the list of transitively
-- imported orphan modules suffice?
--
-- A: If one of our transitive imports adds a new orphan instance, our
-- export hash must change so that modules which import us rebuild. If we just
-- hashed the [Module], the hash would not change even when a new instance was
-- added to a module that already had an orphan instance.
--
-- Q: Why don't we just hash the orphan hashes of our direct dependencies?
-- Why the full transitive closure?
--
-- A: Suppose we have these modules:
--
-- module A where
-- instance Show (a -> b) where
-- module B where
-- import A -- **
-- module C where
-- import A
-- import B
--
-- Whether or not we add or remove the import to A in B affects the
-- orphan hash of B. But it shouldn't really affect the orphan hash
-- of C. If we hashed only direct dependencies, there would be no
-- way to tell that the net effect was a wash, and we'd be forced
-- to recompile C and everything else.
getOrphanHashes :: HscEnv -> [Module] -> IO [Fingerprint]
getOrphanHashes hsc_env mods = do
let
dflags = hsc_dflags hsc_env
ctx = initSDocContext dflags defaultUserStyle
get_orph_hash mod = do
iface <- initIfaceLoad hsc_env . withIfaceErr ctx
$ loadInterface (text "getOrphanHashes") mod ImportBySystem
return (mi_orphan_hash iface)
mapM get_orph_hash mods
{-
************************************************************************
* *
The ABI of an IfaceDecl
* *
************************************************************************
Note [The ABI of an IfaceDecl]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The ABI of a declaration consists of:
(a) the full name of the identifier (inc. module and package,
because these are used to construct the symbol name by which
the identifier is known externally).
(b) the declaration itself, as exposed to clients. That is, the
definition of an Id is included in the fingerprint only if
it is made available as an unfolding in the interface.
(c) the fixity of the identifier (if it exists)
(d) for Ids: rules
(e) for classes: instances, fixity & rules for methods
(f) for datatypes: instances, fixity & rules for constrs
Items (c)-(f) are not stored in the IfaceDecl, but instead appear
elsewhere in the interface file. But they are *fingerprinted* with
the declaration itself. This is done by grouping (c)-(f) in IfaceDeclExtras,
and fingerprinting that as part of the declaration.
-}
type IfaceDeclABI = (Module, IfaceDecl, IfaceDeclExtras)
data IfaceDeclExtras
= IfaceIdExtras IfaceIdExtras
| IfaceDataExtras
(Maybe Fixity) -- Fixity of the tycon itself (if it exists)
[IfaceInstABI] -- Local class and family instances of this tycon
-- See Note [Orphans] in GHC.Core.InstEnv
[AnnPayload] -- Annotations of the type itself
[IfaceIdExtras] -- For each constructor: fixity, RULES and annotations
| IfaceClassExtras
(Maybe Fixity) -- Fixity of the class itself (if it exists)
[IfaceInstABI] -- Local instances of this class *or*
-- of its associated data types
-- See Note [Orphans] in GHC.Core.InstEnv
[AnnPayload] -- Annotations of the type itself
[IfaceIdExtras] -- For each class method: fixity, RULES and annotations
[IfExtName] -- Default methods. If a module
-- mentions a class, then it can
-- instantiate the class and thereby
-- use the default methods, so we must
-- include these in the fingerprint of
-- a class.
| IfaceSynonymExtras (Maybe Fixity) [AnnPayload]
| IfaceFamilyExtras (Maybe Fixity) [IfaceInstABI] [AnnPayload]
| IfacePatSynExtras (Maybe Fixity) [IfaceCompleteMatchABI] -- ^ COMPLETE pragmas that this PatSyn appears in
| IfaceOtherDeclExtras
data IfaceIdExtras
= IdExtras
(Maybe Fixity) -- Fixity of the Id (if it exists)
[IfaceRule] -- Rules for the Id
[AnnPayload] -- Annotations for the Id
[IfaceCompleteMatchABI] -- See Note [Fingerprinting complete matches] for why this is in IdExtras
-- When hashing a class or family instance, we hash only the
-- DFunId or CoAxiom, because that depends on all the
-- information about the instance.
--
type IfaceInstABI = IfExtName -- Name of DFunId or CoAxiom that is evidence for the instance
-- See Note [Fingerprinting complete matches]
type IfaceCompleteMatchABI = (Fingerprint, Maybe IfExtName)
abiDecl :: IfaceDeclABI -> IfaceDecl
abiDecl (_, decl, _) = decl
cmp_abiNames :: IfaceDeclABI -> IfaceDeclABI -> Ordering
cmp_abiNames abi1 abi2 = getOccName (abiDecl abi1) `compare`
getOccName (abiDecl abi2)
freeNamesDeclABI :: IfaceDeclABI -> NameSet
freeNamesDeclABI (_mod, decl, extras) =
freeNamesIfDecl decl `unionNameSet` freeNamesDeclExtras extras
freeNamesDeclExtras :: IfaceDeclExtras -> NameSet
freeNamesDeclExtras (IfaceIdExtras id_extras)
= freeNamesIdExtras id_extras
freeNamesDeclExtras (IfaceDataExtras _ insts _ subs)
= unionNameSets (mkNameSet insts : map freeNamesIdExtras subs)
freeNamesDeclExtras (IfaceClassExtras _ insts _ subs defms)
= unionNameSets $
mkNameSet insts : mkNameSet defms : map freeNamesIdExtras subs
freeNamesDeclExtras (IfaceSynonymExtras _ _)
= emptyNameSet
freeNamesDeclExtras (IfaceFamilyExtras _ insts _)
= mkNameSet insts
freeNamesDeclExtras (IfacePatSynExtras _ complete)
= unionNameSets (map freeNamesIfaceCompleteABI complete)
freeNamesDeclExtras IfaceOtherDeclExtras
= emptyNameSet
freeNamesIdExtras :: IfaceIdExtras -> NameSet
freeNamesIdExtras (IdExtras _ rules _ complete) =
unionNameSets (map freeNamesIfRule rules ++ map freeNamesIfaceCompleteABI complete)
-- | Extract free names from a COMPLETE pragma ABI
freeNamesIfaceCompleteABI :: IfaceCompleteMatchABI -> NameSet
freeNamesIfaceCompleteABI (_, mb_ty) = case mb_ty of
Nothing -> emptyNameSet
Just ty -> unitNameSet ty
instance Outputable IfaceDeclExtras where
ppr IfaceOtherDeclExtras = Outputable.empty
ppr (IfaceIdExtras extras) = ppr_id_extras extras
ppr (IfaceSynonymExtras fix anns) = vcat [ppr fix, ppr anns]
ppr (IfaceFamilyExtras fix finsts anns) = vcat [ppr fix, ppr finsts, ppr anns]
ppr (IfaceDataExtras fix insts anns stuff)
= vcat [ppr fix, ppr_insts insts, ppr anns,
ppr_id_extras_s stuff]
ppr (IfaceClassExtras fix insts anns stuff defms) =
vcat [ppr fix, ppr_insts insts, ppr anns,
ppr_id_extras_s stuff, ppr defms]
ppr (IfacePatSynExtras fix complete) = vcat [ppr fix, ppr complete]
ppr_insts :: [IfaceInstABI] -> SDoc
ppr_insts _ = text "<insts>"
ppr_id_extras_s :: [IfaceIdExtras] -> SDoc
ppr_id_extras_s stuff = vcat (map ppr_id_extras stuff)
ppr_id_extras :: IfaceIdExtras -> SDoc
ppr_id_extras (IdExtras fix rules anns complete) = ppr fix $$ vcat (map ppr rules) $$ vcat (map ppr anns) $$ vcat (map ppr complete)
-- This instance is used only to compute fingerprints
instance Binary IfaceDeclExtras where
get _bh = panic "no get for IfaceDeclExtras"
put_ bh (IfaceIdExtras extras) = do
putByte bh 1; put_ bh extras
put_ bh (IfaceDataExtras fix insts anns cons) = do
putByte bh 2; put_ bh fix; put_ bh insts; put_ bh anns; put_ bh cons
put_ bh (IfaceClassExtras fix insts anns methods defms) = do
putByte bh 3
put_ bh fix
put_ bh insts
put_ bh anns
put_ bh methods
put_ bh defms
put_ bh (IfaceSynonymExtras fix anns) = do
putByte bh 4; put_ bh fix; put_ bh anns
put_ bh (IfaceFamilyExtras fix finsts anns) = do
putByte bh 5; put_ bh fix; put_ bh finsts; put_ bh anns
put_ bh (IfacePatSynExtras fix complete) = do
putByte bh 6; put_ bh fix; put_ bh complete
put_ bh IfaceOtherDeclExtras = putByte bh 7
instance Binary IfaceIdExtras where
get _bh = panic "no get for IfaceIdExtras"
put_ bh (IdExtras fix rules anns complete) = do { put_ bh fix; put_ bh rules; put_ bh anns; put_ bh complete }
declExtras :: (OccName -> Maybe Fixity)
-> (AnnCacheKey -> [AnnPayload])
-> OccEnv [IfaceRule]
-> OccEnv [IfaceClsInst]
-> OccEnv [IfaceFamInst]
-> OccEnv IfExtName -- lookup default method names
-> OccEnv [IfaceCompleteMatchABI] -- lookup complete matches
-> IfaceDecl
-> IfaceDeclExtras
declExtras fix_fn ann_fn rule_env inst_env fi_env dm_env complete_env decl
= case decl of
IfaceId{} -> IfaceIdExtras (id_extras n)
IfaceData{ifCons=cons} ->
IfaceDataExtras (fix_fn n)
(map ifFamInstAxiom (lookupOccEnvL fi_env n) ++
map ifDFun (lookupOccEnvL inst_env n))
(ann_fn (AnnOccName n))
(map (id_extras . occName . ifConName) (visibleIfConDecls cons))
IfaceClass{ifBody = IfConcreteClass { ifSigs=sigs, ifATs=ats }} ->
IfaceClassExtras (fix_fn n) insts (ann_fn (AnnOccName n)) meths defms
where
insts = (map ifDFun $ (concatMap at_extras ats)
++ lookupOccEnvL inst_env n)
-- Include instances of the associated types
-- as well as instances of the class (#5147)
meths = [id_extras (getOccName op) | IfaceClassOp op _ _ <- sigs]
-- Names of all the default methods (see Note [default method Name])
defms = [ dmName
| IfaceClassOp bndr _ (Just _) <- sigs
, let dmOcc = mkDefaultMethodOcc (nameOccName bndr)
, Just dmName <- [lookupOccEnv dm_env dmOcc] ]
IfaceSynonym{} -> IfaceSynonymExtras (fix_fn n)
(ann_fn (AnnOccName n))
IfaceFamily{} -> IfaceFamilyExtras (fix_fn n)
(map ifFamInstAxiom (lookupOccEnvL fi_env n))
(ann_fn (AnnOccName n))
IfacePatSyn{} -> IfacePatSynExtras (fix_fn n) (lookup_complete_match n)
_other -> IfaceOtherDeclExtras
where
n = getOccName decl
id_extras occ = IdExtras (fix_fn occ) (lookupOccEnvL rule_env occ) (ann_fn (AnnOccName occ)) (lookup_complete_match occ)
at_extras (IfaceAT decl _) = lookupOccEnvL inst_env (getOccName decl)
lookup_complete_match occ = lookupOccEnvL complete_env occ
{- Note [default method Name] (see also #15970)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The Names for the default methods aren't available in Iface syntax.
* We originally start with a DefMethInfo from the class, contain a
Name for the default method
* We turn that into Iface syntax as a DefMethSpec which lacks a Name
entirely. Why? Because the Name can be derived from the method name
(in GHC.IfaceToCore), so doesn't need to be serialised into the interface
file.
But now we have to get the Name back, because the class declaration's
fingerprint needs to depend on it (this was the bug in #15970). This
is done in a slightly convoluted way:
* Then, in addFingerprints we build a map that maps OccNames to Names
* We pass that map to declExtras which laboriously looks up in the map
(using the derived occurrence name) to recover the Name we have just
thrown away.
-}
lookupOccEnvL :: OccEnv [v] -> OccName -> [v]
lookupOccEnvL env k = lookupOccEnv env k `orElse` []
{-
-- for testing: use the md5sum command to generate fingerprints and
-- compare the results against our built-in version.
fp' <- oldMD5 dflags bh
if fp /= fp' then pprPanic "computeFingerprint" (ppr fp <+> ppr fp')
else return fp
oldMD5 dflags bh = do
tmp <- newTempName dflags CurrentModule "bin"
writeBinMem bh tmp
tmp2 <- newTempName dflags CurrentModule "md5"
let cmd = "md5sum " ++ tmp ++ " >" ++ tmp2
r <- system cmd
case r of
ExitFailure _ -> throwGhcExceptionIO (PhaseFailed cmd r)
ExitSuccess -> do
hash_str <- readFile tmp2
return $! readHexFingerprint hash_str
-}
----------------------
-- mkOrphMap partitions instance decls or rules into
-- (a) an OccEnv for ones that are not orphans,
-- mapping the local OccName to a list of its decls
-- (b) a list of orphan decls
mkOrphMap :: (decl -> IsOrphan) -- Extract orphan status from decl
-> [decl] -- Sorted into canonical order
-> (OccEnv [decl], -- Non-orphan decls associated with their key;
-- each sublist in canonical order
[decl]) -- Orphan decls; in canonical order
mkOrphMap get_key decls
= foldl' go (emptyOccEnv, []) decls
where
go (non_orphs, orphs) d
| NotOrphan occ <- get_key d
= (extendOccEnv_Acc (:) Utils.singleton non_orphs occ d, orphs)
| otherwise = (non_orphs, d:orphs)
-- -----------------------------------------------------------------------------
-- Look up parents and versions of Names
-- This is like a global version of the mi_hash_fn field in each ModIface.
-- Given a Name, it finds the ModIface, and then uses mi_hash_fn to get
-- the parent and version info.
mkHashFun
:: HscEnv -- needed to look up versions
-> ExternalPackageState -- ditto
-> (Name -> IO Fingerprint)
mkHashFun hsc_env eps name
| isHoleModule orig_mod
= lookup (mkHomeModule home_unit (moduleName orig_mod))
| otherwise
= lookup orig_mod
where
home_unit = hsc_home_unit hsc_env
dflags = hsc_dflags hsc_env
hpt = hsc_HUG hsc_env
pit = eps_PIT eps
ctx = initSDocContext dflags defaultUserStyle
occ = nameOccName name
orig_mod = nameModule name
lookup mod = do
massertPpr (isExternalName name) (ppr name)
iface <- lookupIfaceByModule hpt pit mod >>= \case
Just iface -> return iface
Nothing ->
-- This can occur when we're writing out ifaces for
-- requirements; we didn't do any /real/ typechecking
-- so there's no guarantee everything is loaded.
-- Kind of a heinous hack.
initIfaceLoad hsc_env . withIfaceErr ctx
$ withoutDynamicNow
-- If you try and load interfaces when dynamic-too
-- enabled then it attempts to load the dyn_hi and hi
-- interface files. Backpack doesn't really care about
-- dynamic object files as it isn't doing any code
-- generation so -dynamic-too is turned off.
-- Some tests fail without doing this (such as T16219),
-- but they fail because dyn_hi files are not found for
-- one of the dependencies (because they are deliberately turned off)
-- Why is this check turned off here? That is unclear but
-- just one of the many horrible hacks in the backpack
-- implementation.
$ loadInterface (text "lookupVers2") mod ImportBySystem
return $ snd (mi_hash_fn iface occ `orElse`
pprPanic "lookupVers1" (ppr mod <+> ppr occ))
{- Note [Fingerprinting complete matches]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The presence or absence of COMPLETE pragmas influences the programs we generate,
and not just error messages, because pattern fallibility information feeds into
the desugaring of do notation (e.g. whether to use 'fail' from 'MonadFail').
As far as recompilation checking is concerned, there are two questions we need
to answer:
Usage: When is a COMPLETE pragma used?
Fingerprinting: What is the Fingerprint of a COMPLETE pragma, i.e. when
do we consider a COMPLETE pragma to have changed?
Usage
There isn't a straightforward way to compute which COMPLETE pragmas are
"used" during pattern-match checking. So we have to come up with a conservative
approximation.
The most conservative option is to consider a COMPLETE pragma to always be
used, much like we treat orphan class instances today. This means that any
change at all would require recompilation.
A slightly finer grained option, which is what is currently implemented, is to
consider a COMPLETE pragma to be used only when the importing module actually
mentions at least one of the constructors in the COMPLETE pragma.
Tested in: RecompCompletePragma
Fingerprinting
Most conservatively, the fingerprint of a COMPLETE pragma would be the hash of
all the constructors it mentions (together with the hash of the result TyCon,
if any).
However, for the purposes of the pattern-match checker, we only really care
about the Names of the constructors in a COMPLETE pragma; it doesn't matter
what the definitions of the constructors are. The above criterion would
pessimistically lead to recompilation in the following scenario:
module M where
pattern MyJust :: a -> Maybe a
pattern MyJust a = Just a
pattern MyNothing :: Maybe a
pattern MyNothing = Nothing
{-# COMPLETE MyJust, MyNothing #-}
module N where
import M
f :: Maybe Int -> Int
f (MyJust x) = x; f _ = 0
In this example, if we change the definition of the 'MyNothing' pattern, then
we will recompile 'M', because 'N' uses the 'MyJust' constructor, 'MyJust'
appears in the imported {-# COMPLETE MyJust, MyNothing #-} pragma, and
'MyNothing' has changed.
However, this is needless: the RHS of the pattern synonym declaration for
'MyNothing' is completely irrelevant to 'N'. So, to avoid this extraneous
recompilation, we implement the following finer-grained criterion: the
Fingerprint of a COMPLETE pragma is the hash of the 'Name's of the mentioned
constructors (hashed together with the Fingerprint of the result TyCon, if any).
Tested in: RecompCompleteIndependence.
-}
-- | Make a map from OccNames of pattern synonyms or data constructors to a list
-- of COMPLETE pragmas relevant for that OccName.
-- See Note [Fingerprinting complete matches]
mkIfaceCompleteMap :: [IfaceCompleteMatch] -> OccEnv [IfaceCompleteMatchABI]
mkIfaceCompleteMap complete =
mkOccEnv_C (++) $
concatMap (\m@(IfaceCompleteMatch syns _) ->
let complete_abi = mkIfaceCompleteMatchABI m
in [(getOccName syn, [complete_abi]) | syn <- syns]
) complete
where
mkIfaceCompleteMatchABI (IfaceCompleteMatch syns ty) =
(computeFingerprint putNameLiterally syns, ty)
data AnnCacheKey = AnnModule | AnnOccName OccName
-- | Creates cached lookup for the 'mi_anns' field of ModIface
mkIfaceAnnCache :: [IfaceAnnotation] -> AnnCacheKey -> [AnnPayload]
mkIfaceAnnCache anns
= \n -> case n of
AnnModule -> module_anns
AnnOccName occn -> lookupOccEnv env occn `orElse` []
where
(module_anns, occ_anns) = partitionEithers $ map classify anns
classify (IfaceAnnotation target value) =
case target of
NamedTarget occn -> Right (occn, [value])
ModuleTarget _ -> Left value
-- flipping (++), so the first argument is always short
env = mkOccEnv_C (flip (++)) occ_anns