Merge pull request #7380 from haskell/mergify/bp/3.6/pr-7378

Fix --only-download making install fail (backport #7378)
haskell · May 4, 2021 · 795d57c · 795d57c
2 parents 5771a24 + 7fd9b25
commit 795d57c
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Showing 2 changed files with 13 additions and 7 deletions.
diff --git a/cabal-install/src/Distribution/Client/CmdInstall.hs b/cabal-install/src/Distribution/Client/CmdInstall.hs
@@ -2,7 +2,6 @@
 {-# LANGUAGE NamedFieldPuns      #-}
 {-# LANGUAGE RecordWildCards     #-}
 {-# LANGUAGE ScopedTypeVariables #-}
-{-# LANGUAGE ViewPatterns        #-}
 
 -- | cabal-install CLI command: build
 --
@@ -46,7 +45,8 @@ import Distribution.Types.PackageId
 import Distribution.Client.ProjectConfig
          ( ProjectPackageLocation(..)
          , fetchAndReadSourcePackages
-         )
+         , projectConfigWithBuilderRepoContext
+         , resolveBuildTimeSettings, withProjectOrGlobalConfig )
 import Distribution.Client.NixStyleOptions
          ( NixStyleFlags (..), nixStyleOptions, defaultNixStyleFlags )
 import Distribution.Client.ProjectFlags (ProjectFlags (..))
@@ -78,9 +78,6 @@ import Distribution.Solver.Types.PackageConstraint
          ( PackageProperty(..) )
 import Distribution.Client.IndexUtils
          ( getSourcePackages, getInstalledPackages )
-import Distribution.Client.ProjectConfig
-         ( projectConfigWithBuilderRepoContext
-         , resolveBuildTimeSettings, withProjectOrGlobalConfig )
 import Distribution.Client.ProjectPlanning
          ( storePackageInstallDirs' )
 import Distribution.Client.ProjectPlanning.Types
@@ -382,10 +379,11 @@ installAction flags@NixStyleFlags { extraFlags = clientInstallFlags', .. } targe
     -- Now that we built everything we can do the installation part.
     -- First, figure out if / what parts we want to install:
     let
-      dryRun = buildSettingDryRun $ buildSettings baseCtx
+      dryRun = buildSettingDryRun (buildSettings baseCtx)
+            || buildSettingOnlyDownload (buildSettings baseCtx)
 
     -- Then, install!
-    when (not dryRun) $
+    unless dryRun $
       if installLibs
       then installLibraries verbosity
            buildCtx compiler packageDbs progDb envFile nonGlobalEnvEntries

diff --git a/cabal-install/src/Distribution/Client/ProjectBuilding.hs b/cabal-install/src/Distribution/Client/ProjectBuilding.hs
@@ -653,6 +653,14 @@ rebuildTarget verbosity
               sharedPackageConfig
               plan rpkg@(ReadyPackage pkg)
               pkgBuildStatus
+    -- Technically, doing the --only-download filtering only in this function is
+    -- not perfect. We could also prune the plan at an earlier stage, like it's
+    -- done with --only-dependencies. But...
+    --   * the benefit would be minimal (practically just avoiding to print the
+    --     "requires build" parts of the plan)
+    --   * we currently don't have easy access to the BuildStatus of packages
+    --     in the pruning phase
+    --   * we still have to check it here to avoid performing successive phases
     | buildSettingOnlyDownload buildSettings = do
         case pkgBuildStatus of
           BuildStatusDownload ->