[commit: ghc] master: Add a workaround to allow older cabal-install to use ghc-7.10 (a1db53c)
git at git.haskell.org
git at git.haskell.org
Tue Feb 10 14:01:45 UTC 2015
Repository : ssh://git@git.haskell.org/ghc
On branch : master
Link : http://ghc.haskell.org/trac/ghc/changeset/a1db53cc6ea03d80f097c550bae277141b03ac30/ghc
>---------------------------------------------------------------
commit a1db53cc6ea03d80f097c550bae277141b03ac30
Author: Duncan Coutts <duncan at well-typed.com>
Date: Mon Feb 9 13:46:06 2015 -0600
Add a workaround to allow older cabal-install to use ghc-7.10
Summary:
This should smooth the upgrade process for people and help with testing
the 7.10 RCs. Otherwise people need to first install cabal-install-1.22
before they can use 7.10.
The problem is that older cabal still used file-style package dbs for
the inplace package db when building packages. The workaround is that
both ghc and ghc-pkg will notice when cabal tells them to use a file
style db e.g. "dist/package.conf.inplace" and, so long as that db is
empty (ie content is []) then they'll instead us a dir style db with
the same name but ".d" appended, so in this example that would be
"dist/package.conf.inplace.d". We have to use a separate dir rather
than transparently upgrading because old Cabal really assumes the path
is a file, and if it encounters a dir it will fail.
This seems to be enough for older Cabal to work, and may well be enough
for other scripts that create dbs using "echo [] > package.conf".
Test Plan:
validate and check new and old cabal can sucessfully install things,
including packages that have internal deps (ie using the inplace db)
Reviewers: hvr, tibbe, austin
Reviewed By: tibbe, austin
Subscribers: thomie
Differential Revision: https://phabricator.haskell.org/D628
>---------------------------------------------------------------
a1db53cc6ea03d80f097c550bae277141b03ac30
compiler/main/Packages.hs | 35 +++++++++++++++++---
utils/ghc-pkg/Main.hs | 82 +++++++++++++++++++++++++++++++++++++++++++----
2 files changed, 107 insertions(+), 10 deletions(-)
diff --git a/compiler/main/Packages.hs b/compiler/main/Packages.hs
index 28f2f2d..db48d99 100644
--- a/compiler/main/Packages.hs
+++ b/compiler/main/Packages.hs
@@ -367,13 +367,15 @@ readPackageConfig dflags conf_file = do
proto_pkg_configs <-
if isdir
- then do let filename = conf_file </> "package.cache"
- debugTraceMsg dflags 2 (text "Using binary package database:" <+> text filename)
- readPackageDbForGhc filename
+ then readDirStylePackageConfig conf_file
else do
isfile <- doesFileExist conf_file
if isfile
- then throwGhcExceptionIO $ InstallationError $
+ then do
+ mpkgs <- tryReadOldFileStylePackageConfig
+ case mpkgs of
+ Just pkgs -> return pkgs
+ Nothing -> throwGhcExceptionIO $ InstallationError $
"ghc no longer supports single-file style package " ++
"databases (" ++ conf_file ++
") use 'ghc-pkg init' to create the database with " ++
@@ -388,6 +390,31 @@ readPackageConfig dflags conf_file = do
pkg_configs2 = setBatchPackageFlags dflags pkg_configs1
--
return pkg_configs2
+ where
+ readDirStylePackageConfig conf_dir = do
+ let filename = conf_dir </> "package.cache"
+ debugTraceMsg dflags 2 (text "Using binary package database:" <+> text filename)
+ readPackageDbForGhc filename
+
+ -- Single-file style package dbs have been deprecated for some time, but
+ -- it turns out that Cabal was using them in one place. So this is a
+ -- workaround to allow older Cabal versions to use this newer ghc.
+ -- We check if the file db contains just "[]" and if so, we look for a new
+ -- dir-style db in conf_file.d/, ie in a dir next to the given file.
+ -- We cannot just replace the file with a new dir style since Cabal still
+ -- assumes it's a file and tries to overwrite with 'writeFile'.
+ -- ghc-pkg also cooperates with this workaround.
+ tryReadOldFileStylePackageConfig = do
+ content <- readFile conf_file `catchIO` \_ -> return ""
+ if take 2 content == "[]"
+ then do
+ let conf_dir = conf_file <.> "d"
+ direxists <- doesDirectoryExist conf_dir
+ if direxists
+ then do debugTraceMsg dflags 2 (text "Ignoring old file-style db and trying:" <+> text conf_dir)
+ liftM Just (readDirStylePackageConfig conf_dir)
+ else return (Just []) -- ghc-pkg will create it when it's updated
+ else return Nothing
setBatchPackageFlags :: DynFlags -> [PackageConfig] -> [PackageConfig]
setBatchPackageFlags dflags pkgs = maybeDistrustAll pkgs
diff --git a/utils/ghc-pkg/Main.hs b/utils/ghc-pkg/Main.hs
index 0493866..b2815b8 100644
--- a/utils/ghc-pkg/Main.hs
+++ b/utils/ghc-pkg/Main.hs
@@ -680,10 +680,18 @@ readParseDatabase verbosity mb_user_conf modify use_cache path
= do e <- tryIO $ getDirectoryContents path
case e of
Left err
- | ioeGetErrorType err == InappropriateType ->
- die ("ghc no longer supports single-file style package databases "
- ++ "(" ++ path ++ ") use 'ghc-pkg init' to create the database "
- ++ "with the correct format.")
+ | ioeGetErrorType err == InappropriateType -> do
+ -- We provide a limited degree of backwards compatibility for
+ -- old single-file style db:
+ mdb <- tryReadParseOldFileStyleDatabase verbosity
+ mb_user_conf modify use_cache path
+ case mdb of
+ Just db -> return db
+ Nothing ->
+ die $ "ghc no longer supports single-file style package "
+ ++ "databases (" ++ path ++ ") use 'ghc-pkg init'"
+ ++ "to create the database with the correct format."
+
| otherwise -> ioError err
Right fs
| not use_cache -> ignore_cache (const $ return ())
@@ -823,6 +831,67 @@ mungePackagePaths top_dir pkgroot pkg =
-- -----------------------------------------------------------------------------
+-- Workaround for old single-file style package dbs
+
+-- Single-file style package dbs have been deprecated for some time, but
+-- it turns out that Cabal was using them in one place. So this code is for a
+-- workaround to allow older Cabal versions to use this newer ghc.
+
+-- We check if the file db contains just "[]" and if so, we look for a new
+-- dir-style db in path.d/, ie in a dir next to the given file.
+-- We cannot just replace the file with a new dir style since Cabal still
+-- assumes it's a file and tries to overwrite with 'writeFile'.
+
+-- ghc itself also cooperates in this workaround
+
+tryReadParseOldFileStyleDatabase :: Verbosity -> Maybe (FilePath, Bool)
+ -> Bool -> Bool -> FilePath
+ -> IO (Maybe PackageDB)
+tryReadParseOldFileStyleDatabase verbosity mb_user_conf modify use_cache path = do
+ -- assumes we've already established that path exists and is not a dir
+ content <- readFile path `catchIO` \_ -> return ""
+ if take 2 content == "[]"
+ then do
+ path_abs <- absolutePath path
+ let path_dir = path <.> "d"
+ warn $ "Warning: ignoring old file-style db and trying " ++ path_dir
+ direxists <- doesDirectoryExist path_dir
+ if direxists
+ then do db <- readParseDatabase verbosity mb_user_conf
+ modify use_cache path_dir
+ -- but pretend it was at the original location
+ return $ Just db {
+ location = path,
+ locationAbsolute = path_abs
+ }
+ else return $ Just PackageDB {
+ location = path,
+ locationAbsolute = path_abs,
+ packages = []
+ }
+
+ -- if the path is not a file, or is not an empty db then we fail
+ else return Nothing
+
+adjustOldFileStylePackageDB :: PackageDB -> IO PackageDB
+adjustOldFileStylePackageDB db = do
+ -- assumes we have not yet established if it's an old style or not
+ mcontent <- liftM Just (readFile (location db)) `catchIO` \_ -> return Nothing
+ case fmap (take 2) mcontent of
+ -- it is an old style and empty db, so look for a dir kind in location.d/
+ Just "[]" -> return db {
+ location = location db <.> "d",
+ locationAbsolute = locationAbsolute db <.> "d"
+ }
+ -- it is old style but not empty, we have to bail
+ Just _ -> die $ "ghc no longer supports single-file style package "
+ ++ "databases (" ++ location db ++ ") use 'ghc-pkg init'"
+ ++ "to create the database with the correct format."
+ -- probably not old style, carry on as normal
+ Nothing -> return db
+
+
+-- -----------------------------------------------------------------------------
-- Creating a new package DB
initPackageDB :: FilePath -> Verbosity -> [Flag] -> IO ()
@@ -941,8 +1010,9 @@ data DBOp = RemovePackage InstalledPackageInfo
changeDB :: Verbosity -> [DBOp] -> PackageDB -> IO ()
changeDB verbosity cmds db = do
let db' = updateInternalDB db cmds
- createDirectoryIfMissing True (location db)
- changeDBDir verbosity cmds db'
+ db'' <- adjustOldFileStylePackageDB db'
+ createDirectoryIfMissing True (location db'')
+ changeDBDir verbosity cmds db''
updateInternalDB :: PackageDB -> [DBOp] -> PackageDB
updateInternalDB db cmds = db{ packages = foldl do_cmd (packages db) cmds }
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