Fix handling of package-db entries in .ghc.environment files, etc.

Previously interpreting the content of the .ghc.env files was done
after the step that loaded the available package dbs. This meant that
setting the package db flags was ineffective. This patch moves
interpreting the env files before loading of the package dbs.

Also, the package-db entries refer to files. Allow spaces in these file
names. Also treat as comments lines beginning with "--".

These are pretty minor fixes in a feature that up 'til now has been
essentially unused (witness no bug report about it), so there's very
low risk here. If we can get this into 8.0.2 then cabal can start
generating the .ghc.environment files, otherwise it cannot as it needs
the working package-db entries, to be able to refer to local package
dbs in the build tree (or cabal nix store).

Test Plan:
Manually create example .ghc.env files
run ghci; :show packages
Done this. It works.

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D2476

2 files changed, 6 insertions, 5 deletions

diff --git a/compiler/main/DynFlags.hs b/compiler/main/DynFlags.hs
index c1ccfcd95c..4081ac4684 100644
--- a/compiler/main/DynFlags.hs
+++ b/compiler/main/DynFlags.hs
@@ -4410,13 +4410,15 @@ interpretPackageEnv dflags = do
     parseEnvFile envfile = mapM_ parseEntry . lines
       where
         parseEntry str = case words str of
-          ["package-db", db]    -> addPkgConfRef (PkgConfFile (envdir </> db))
+          ("package-db": _)     -> addPkgConfRef (PkgConfFile (envdir </> db))
             -- relative package dbs are interpreted relative to the env file
             where envdir = takeDirectory envfile
+                  db     = drop 11 str
           ["clear-package-db"]  -> clearPkgConf
           ["global-package-db"] -> addPkgConfRef GlobalPkgConf
           ["user-package-db"]   -> addPkgConfRef UserPkgConf
           ["package-id", pkgid] -> exposePackageId pkgid
+          (('-':'-':_):_)       -> return () -- comments
           -- and the original syntax introduced in 7.10:
           [pkgid]               -> exposePackageId pkgid
           []                    -> return ()
diff --git a/compiler/main/Packages.hs b/compiler/main/Packages.hs
index ecec982422..0c91af284d 100644
--- a/compiler/main/Packages.hs
+++ b/compiler/main/Packages.hs
@@ -339,7 +339,8 @@ listPackageConfigMap dflags = eltsUDFM (pkgIdMap (pkgState dflags))
 -- 'pkgState' in 'DynFlags' and return a list of packages to
 -- link in.
 initPackages :: DynFlags -> IO (DynFlags, [UnitId])
-initPackages dflags = do
+initPackages dflags0 = do
+  dflags <- interpretPackageEnv dflags0
   pkg_db <-
     case pkgDatabase dflags of
         Nothing -> readPackageConfigs dflags
@@ -879,9 +880,7 @@ mkPackageState
            UnitId) -- this package, might be modified if the current
                       -- package is a wired-in package.
 
-mkPackageState dflags0 dbs preload0 = do
-  dflags <- interpretPackageEnv dflags0
-
+mkPackageState dflags dbs preload0 = do
   -- Compute the unit id
   let this_package = thisPackage dflags