Merge pull request #4676 from commercialhaskell/3861-ignore-globals-i…

…n-snapshot-plan

Ignore dependencies in snapshot

src/Stack/Build/ConstructPlan.hs

@@ -56,12 +56,11 @@ import           RIO.Process (findExecutable, HasProcessContext (..))
 data PackageInfo
     =
       -- | This indicates that the package is already installed, and
-      -- that we shouldn't build it from source. This is always the case
-      -- for snapshot packages.
+      -- that we shouldn't build it from source. This is only the case
+      -- for global packages.
       PIOnlyInstalled InstallLocation Installed
       -- | This indicates that the package isn't installed, and we know
-      -- where to find its source (either a hackage package or a local
-      -- directory).
+      -- where to find its source.
     | PIOnlySource PackageSource
       -- | This indicates that the package is installed and we know
       -- where to find its source. We may want to reinstall from source.
@@ -701,16 +700,12 @@ addPackageDeps package = do
                                 warn_ " (allow-newer enabled)"
                                 return True
                             else do
-                                -- TODO: dependencies between snapshot packages are allowed
-                                -- to ignore bounds, MSS told an idea to tag explicitly
-                                -- dependencies for which bounds could be ignored and why,
-                                -- this needs to be explored,
-                                -- the current designed is based on #3185 for Stackage
+                                -- We ignore dependency information for packages in a snapshot
                                 x <- inSnapshot (packageName package) (packageVersion package)
                                 y <- inSnapshot depname (adrVersion adr)
                                 if x && y
                                     then do
-                                        warn_ " (trusting snapshot over Hackage revisions)"
+                                        warn_ " (trusting snapshot over cabal file dependency information)"
                                         return True
                                     else return False
                 if inRange
@@ -950,7 +945,7 @@ stripNonDeps deps plan = plan
       modify'(<> Set.singleton pid)
       mapM_ (collectMissing (pid:dependents)) (fromMaybe mempty $ M.lookup pid missing)
 
--- | Is the given package/version combo defined in the snapshot?
+-- | Is the given package/version combo defined in the snapshot or in the global database?
 inSnapshot :: PackageName -> Version -> M Bool
 inSnapshot name version = do
     ctx <- ask
@@ -961,6 +956,11 @@ inSnapshot name version = do
                 return $ srcVersion == version
             PIBoth (PSRemote _ srcVersion FromSnapshot _) _ ->
                 return $ srcVersion == version
+            -- OnlyInstalled occurs for global database
+            PIOnlyInstalled loc (Library pid _gid _lic) ->
+              assert (loc == Snap) $
+              assert (pkgVersion pid == version) $
+              Just True
             _ -> return False
 
 data ConstructPlanException