Commit 1c5fb336 authored by Simon Marlow's avatar Simon Marlow

Fix bug when the combined package DB has duplicate package IDs

Someone on IRC reported that they were encountering a strange missing
module error from GHC, and it turned out that they had mtl-
installed in both the global and local DB, with the same
InstalledPackageId.  The two packages should be interchangeable, but
we were forgetting to eliminate duplicates in part of the
package-processing phase in GHC.

Really I should switch this code over to use the new PackageIndex data
type in Cabal, which ought to make things simpler.
parent 51b5bc7d
......@@ -658,6 +658,14 @@ mkPackageState dflags pkgs0 preload0 this_package = do
ipid_map = listToFM [ (installedPackageId p, p) | p <- pkgs0 ]
-- pkgs0 with duplicate packages filtered out. This is
-- important: it is possible for a package in the user package
-- DB to have the same IPID as a package in the global DB, and
-- we want the former to take precedence. This is not the same
-- as shadowing (below), since in this case the two packages
-- have the same ABI and are interchangeable.
pkgs0_unique = eltsFM ipid_map
ipid_selected = depClosure ipid_map [ InstalledPackageId i
| ExposePackageId i <- flags ]
......@@ -665,11 +673,11 @@ mkPackageState dflags pkgs0 preload0 this_package = do
is_ignore IgnorePackage{} = True
is_ignore _ = False
shadowed = shadowPackages pkgs0 ipid_selected
shadowed = shadowPackages pkgs0_unique ipid_selected
ignored = ignorePackages ignore_flags pkgs0
ignored = ignorePackages ignore_flags pkgs0_unique
pkgs0' = filter (not . (`elemFM` (plusFM shadowed ignored)) . installedPackageId) pkgs0
pkgs0' = filter (not . (`elemFM` (plusFM shadowed ignored)) . installedPackageId) pkgs0_unique
broken = findBroken pkgs0'
unusable = shadowed `plusFM` ignored `plusFM` broken
......@@ -679,7 +687,7 @@ mkPackageState dflags pkgs0 preload0 this_package = do
-- Modify the package database according to the command-line flags
-- (-package, -hide-package, -ignore-package, -hide-all-packages).
pkgs1 <- foldM (applyPackageFlag unusable) pkgs0 other_flags
pkgs1 <- foldM (applyPackageFlag unusable) pkgs0_unique other_flags
let pkgs2 = filter (not . (`elemFM` unusable) . installedPackageId) pkgs1
-- Here we build up a set of the packages mentioned in -package
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