Commit 13ff0b7c authored by Edward Z. Yang's avatar Edward Z. Yang Committed by Edward Z. Yang
Browse files

Fix #15594 (--abi-hash with Backpack sometimes fails)

Summary:
For holes, its necessary to "see through" the instantiation
of the hole to get accurate family instance dependencies.
For example, if B imports <A>, and <A> is instantiated with
F, we must grab and include all of the dep_finsts from
F to have an accurate transitive dep_finsts list.

However, we MUST NOT do this for regular modules.
First, for efficiency reasons, doing this
bloats the the dep_finsts list, because we *already* had
those modules in the list (it wasn't a hole module, after
all). But there's a second, more important correctness
consideration: we perform module renaming when running
--abi-hash.  In this case, GHC's contract to the user is that
it will NOT go and read out interfaces of any dependencies
(https://github.com/haskell/cabal/issues/3633);

 the point of
--abi-hash is just to get a hash of the on-disk interfaces
for this *specific* package.  If we go off and tug on the
interface for /everything/ in dep_finsts, we're gonna have a
bad time.  (It's safe to do do this for hole modules, though,
because the hmap for --abi-hash is always trivial, so the
interface we request is local.  Though, maybe we ought
not to do it in this case either...)
Signed-off-by: Edward Z. Yang's avatarEdward Z. Yang <ezyang@fb.com>

Test Plan: validate

Reviewers: alexbiehl, goldfire, bgamari

Subscribers: ppk, shlevy, rwbarton, carter

GHC Trac Issues: #15594

Differential Revision: https://phabricator.haskell.org/D5123
parent 98f8e1c2
......@@ -138,10 +138,36 @@ rnDepModules sel deps = do
-- in these dependencies.
fmap (nubSort . concat) . T.forM (sel deps) $ \mod -> do
dflags <- getDynFlags
-- For holes, its necessary to "see through" the instantiation
-- of the hole to get accurate family instance dependencies.
-- For example, if B imports <A>, and <A> is instantiated with
-- F, we must grab and include all of the dep_finsts from
-- F to have an accurate transitive dep_finsts list.
--
-- However, we MUST NOT do this for regular modules.
-- First, for efficiency reasons, doing this
-- bloats the the dep_finsts list, because we *already* had
-- those modules in the list (it wasn't a hole module, after
-- all). But there's a second, more important correctness
-- consideration: we perform module renaming when running
-- --abi-hash. In this case, GHC's contract to the user is that
-- it will NOT go and read out interfaces of any dependencies
-- (https://github.com/haskell/cabal/issues/3633); the point of
-- --abi-hash is just to get a hash of the on-disk interfaces
-- for this *specific* package. If we go off and tug on the
-- interface for /everything/ in dep_finsts, we're gonna have a
-- bad time. (It's safe to do do this for hole modules, though,
-- because the hmap for --abi-hash is always trivial, so the
-- interface we request is local. Though, maybe we ought
-- not to do it in this case either...)
--
-- This mistake was bug #15594.
let mod' = renameHoleModule dflags hmap mod
iface <- liftIO . initIfaceCheck (text "rnDepModule") hsc_env
$ loadSysInterface (text "rnDepModule") mod'
return (mod' : sel (mi_deps iface))
if isHoleModule mod
then do iface <- liftIO . initIfaceCheck (text "rnDepModule") hsc_env
$ loadSysInterface (text "rnDepModule") mod'
return (mod' : sel (mi_deps iface))
else return [mod']
{-
************************************************************************
......
TOP=/home/ezyang/Dev/ghc-known-nat/testsuite
include $(TOP)/mk/boilerplate.mk
include $(TOP)/mk/test.mk
SETUP='$(PWD)/Setup' -v0
CONFIGURE=$(SETUP) configure $(CABAL_MINIMAL_BUILD) --with-ghc='$(TEST_HC)' --ghc-options='$(TEST_HC_OPTS)' --package-db='$(PWD)/tmp.d' --prefix='$(PWD)/inst'
T15594: clean
'$(GHC_PKG)' init tmp.d
'$(TEST_HC)' $(TEST_HC_OPTS) -v0 --make Setup
$(CONFIGURE)
$(SETUP) build
$(SETUP) copy
$(SETUP) register
ifneq "$(CLEANUP)" ""
$(MAKE) -s --no-print-directory clean
endif
clean :
$(RM) -rf tmp.d inst dist Setup$(exeext)
import Distribution.Simple
main = defaultMain
signature Sig where
foo :: String
{-# LANGUAGE TypeFamilies #-}
module Stuff where
data family T a
data instance T Int = T Int
test :: String
test =
"test"
if config.cleanup:
cleanup = 'CLEANUP=1'
else:
cleanup = 'CLEANUP=0'
test('T15594',
extra_files(['Setup.hs', 'Stuff.hs', 'Sig.hsig', 'pkg.cabal', 'src']),
run_command,
['$MAKE -s --no-print-directory T15594 ' + cleanup])
cabal-version: 2.0
name: backpack-trans
version: 0.1.0.0
license: BSD3
author: Alex Biehl
maintainer: alex.biehl@target.com
build-type: Simple
library indef
signatures: Sig
exposed-modules: Stuff
build-depends: base
default-language: Haskell2010
library
exposed-modules: Lib
build-depends: base, indef
default-language: Haskell2010
hs-source-dirs: src
module Lib where
import Stuff
doSomeStuff :: String
doSomeStuff =
test
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