Tell the user that a boot package was pruned

Fixes commercialhaskell#4897.

src/Stack/Build/ConstructPlan.hs

@@ -1109,7 +1109,7 @@ pprintExceptions exceptions stackYaml stackRoot parentMap wanted' prunedGlobalDe
             let prunedDeps = map (style Current . fromString . packageNameString) pruned
             in Just $ flow "Can't use GHC boot package" <+>
                       (style Current . fromString . packageNameString $ name) <+>
-                      flow "when it has an overriden dependency, " <+>
+                      flow "when it has an overridden dependency (issue #4510);" <+>
                       flow "you need to add the following as explicit dependencies to the project:" <+>
                       line <+> encloseSep "" "" ", " prunedDeps
         | otherwise = Just $ flow "Unknown package:" <+> (style Current . fromString . packageNameString $ name)
@@ -1121,13 +1121,22 @@ pprintExceptions exceptions stackYaml stackRoot parentMap wanted' prunedGlobalDe
     pprintFlag (name, False) = "-" <> fromString (flagNameString name)
 
     pprintDep (name, (range, mlatestApplicable, badDep)) = case badDep of
-        NotInBuildPlan -> Just $
-            style Error (fromString $ packageNameString name) <+>
-            align ((if range == Cabal.anyVersion
-                      then flow "needed"
-                      else flow "must match" <+> goodRange) <> "," <> softline <>
-                   flow "but the stack configuration has no specified version" <+>
-                   latestApplicable Nothing)
+        NotInBuildPlan
+          | name `elem` fold prunedGlobalDeps -> Just $
+              style Error (fromString $ packageNameString name) <+>
+              align ((if range == Cabal.anyVersion
+                        then flow "needed"
+                        else flow "must match" <+> goodRange) <> "," <> softline <>
+                     flow "but this GHC boot package has been pruned (issue #4510);" <+>
+                     flow "you need to add the package explicitly to extra-deps" <+>
+                     latestApplicable Nothing)
+          | otherwise -> Just $
+              style Error (fromString $ packageNameString name) <+>
+              align ((if range == Cabal.anyVersion
+                        then flow "needed"
+                        else flow "must match" <+> goodRange) <> "," <> softline <>
+                     flow "but the stack configuration has no specified version" <+>
+                     latestApplicable Nothing)
         -- TODO: For local packages, suggest editing constraints
         DependencyMismatch version -> Just $
             (style Error . fromString . packageIdentifierString) (PackageIdentifier name version) <+>

test/integration/tests/4897-boot-package-pruned/Main.hs

@@ -0,0 +1,16 @@
+import Control.Monad (unless)
+import Data.List (isInfixOf)
+import StackTest
+
+planFailure :: String
+planFailure =
+  "but this GHC boot package has been pruned (issue #4510);"
+
+main :: IO ()
+main = do
+  stackErrStderr ["build"] (expectMessage planFailure)
+
+expectMessage :: String -> String -> IO ()
+expectMessage msg stderr = do
+  unless (words msg `isInfixOf` words stderr)
+         (error $ "Expected an error: \n" ++ show msg)

test/integration/tests/4897-boot-package-pruned/files/directory/directory.cabal

@@ -0,0 +1,8 @@
+name:                directory
+version:             1.3.3.0
+build-type:          Simple
+cabal-version:       >=1.10
+
+library
+  build-depends:       base
+  default-language:    Haskell2010

test/integration/tests/4897-boot-package-pruned/files/files.cabal

@@ -0,0 +1,8 @@
+name:                files
+version:             0.1.0.0
+build-type:          Simple
+cabal-version:       >=1.10
+
+library
+  build-depends:       base, directory, process
+  default-language:    Haskell2010

test/integration/tests/4897-boot-package-pruned/files/stack.yaml

@@ -0,0 +1,3 @@
+resolver: lts-13.26
+packages: [.]
+extra-deps: [./directory]