Refactor cabal-install solver config log output

The main goal is to add an intermediate log message type to
the processing of the solver log. Changes to the cabal solver's
output are very minor.

Includes:

* Apply some of @grayjay and @mpickering comments
* Fix #4251

Co-Authored-By: Erik de Castro Lopo <[email protected]>

Author: yvan-sraka

cabal-install-solver/cabal-install-solver.cabal

@@ -95,6 +95,7 @@ library
     Distribution.Solver.Types.SolverId
     Distribution.Solver.Types.SolverPackage
     Distribution.Solver.Types.SourcePackage
+    Distribution.Solver.Types.SummarizedMessage
     Distribution.Solver.Types.Variable
 
   build-depends:

cabal-install-solver/src/Distribution/Solver/Modular.hs

@@ -27,34 +27,51 @@ import Distribution.Solver.Modular.ConfiguredConversion
          ( convCP )
 import qualified Distribution.Solver.Modular.ConflictSet as CS
 import Distribution.Solver.Modular.Dependency
-import Distribution.Solver.Modular.Flag
-import Distribution.Solver.Modular.Index
+    ( Var(..),
+      showVar,
+      ConflictMap,
+      ConflictSet,
+      showConflictSet,
+      RevDepMap )
+import Distribution.Solver.Modular.Flag ( SN(SN), FN(FN) )
+import Distribution.Solver.Modular.Index ( Index )
 import Distribution.Solver.Modular.IndexConversion
          ( convPIs )
 import Distribution.Solver.Modular.Log
          ( SolverFailure(..), displayLogMessages )
 import Distribution.Solver.Modular.Package
          ( PN )
 import Distribution.Solver.Modular.RetryLog
+    ( RetryLog,
+      toProgress,
+      fromProgress,
+      retry,
+      failWith,
+      continueWith )
 import Distribution.Solver.Modular.Solver
          ( SolverConfig(..), PruneAfterFirstSuccess(..), solve )
 import Distribution.Solver.Types.DependencyResolver
+    ( DependencyResolver )
 import Distribution.Solver.Types.LabeledPackageConstraint
+    ( LabeledPackageConstraint, unlabelPackageConstraint )
 import Distribution.Solver.Types.PackageConstraint
-import Distribution.Solver.Types.PackagePath
+    ( PackageConstraint(..), scopeToPackageName )
+import Distribution.Solver.Types.PackagePath ( QPN )
 import Distribution.Solver.Types.PackagePreferences
+    ( PackagePreferences )
 import Distribution.Solver.Types.PkgConfigDb
          ( PkgConfigDb )
 import Distribution.Solver.Types.Progress
-import Distribution.Solver.Types.Variable
+    ( Progress(..), foldProgress, SummarizedMessage(ErrorMsg) )
+import Distribution.Solver.Types.Variable ( Variable(..) )
 import Distribution.System
          ( Platform(..) )
 import Distribution.Simple.Setup
          ( BooleanFlag(..) )
 import Distribution.Simple.Utils
-         ( ordNubBy )
-import Distribution.Verbosity
-
+    ( ordNubBy )
+import Distribution.Verbosity ( normal, verbose )
+import Distribution.Solver.Modular.Message ( renderSummarizedMessage )
 
 -- | Ties the two worlds together: classic cabal-install vs. the modular
 -- solver. Performs the necessary translations before and after.
@@ -120,21 +137,21 @@ solve' :: SolverConfig
        -> (PN -> PackagePreferences)
        -> Map PN [LabeledPackageConstraint]
        -> Set PN
-       -> Progress String String (Assignment, RevDepMap)
+       -> Progress SummarizedMessage String (Assignment, RevDepMap)
 solve' sc cinfo idx pkgConfigDB pprefs gcs pns =
     toProgress $ retry (runSolver printFullLog sc) createErrorMsg
   where
     runSolver :: Bool -> SolverConfig
-              -> RetryLog String SolverFailure (Assignment, RevDepMap)
+              -> RetryLog SummarizedMessage SolverFailure (Assignment, RevDepMap)
     runSolver keepLog sc' =
         displayLogMessages keepLog $
         solve sc' cinfo idx pkgConfigDB pprefs gcs pns
 
     createErrorMsg :: SolverFailure
-                   -> RetryLog String String (Assignment, RevDepMap)
+                   -> RetryLog SummarizedMessage String (Assignment, RevDepMap)
     createErrorMsg failure@(ExhaustiveSearch cs cm) =
       if asBool $ minimizeConflictSet sc
-      then continueWith ("Found no solution after exhaustively searching the "
+      then continueWith (mkErrorMsg $ "Found no solution after exhaustively searching the "
                           ++ "dependency tree. Rerunning the dependency solver "
                           ++ "to minimize the conflict set ({"
                           ++ showConflictSet cs ++ "}).") $
@@ -155,7 +172,7 @@ solve' sc cinfo idx pkgConfigDB pprefs gcs pns =
            rerunSolverForErrorMsg cs ++ finalErrorMsg sc failure
     createErrorMsg failure@BackjumpLimitReached     =
         continueWith
-             ("Backjump limit reached. Rerunning dependency solver to generate "
+             (mkErrorMsg $ "Backjump limit reached. Rerunning dependency solver to generate "
               ++ "a final conflict set for the search tree containing the "
               ++ "first backjump.") $
         retry (runSolver printFullLog sc { pruneAfterFirstSuccess = PruneAfterFirstSuccess True }) $
@@ -181,13 +198,16 @@ solve' sc cinfo idx pkgConfigDB pprefs gcs pns =
           -- original goal order.
           goalOrder' = preferGoalsFromConflictSet cs <> fromMaybe mempty (goalOrder sc)
 
-      in unlines ("Could not resolve dependencies:" : messages (toProgress (runSolver True sc')))
+      in unlines ("Could not resolve dependencies:" : map renderSummarizedMessage (messages (toProgress (runSolver True sc'))))
 
     printFullLog = solverVerbosity sc >= verbose
 
     messages :: Progress step fail done -> [step]
     messages = foldProgress (:) (const []) (const [])
 
+mkErrorMsg :: String -> SummarizedMessage
+mkErrorMsg msg = ErrorMsg msg
+
 -- | Try to remove variables from the given conflict set to create a minimal
 -- conflict set.
 --
@@ -219,11 +239,11 @@ solve' sc cinfo idx pkgConfigDB pprefs gcs pns =
 --    solver to add new unnecessary variables to the conflict set. This function
 --    discards the result from any run that adds new variables to the conflict
 --    set, but the end result may not be completely minimized.
-tryToMinimizeConflictSet :: forall a . (SolverConfig -> RetryLog String SolverFailure a)
+tryToMinimizeConflictSet :: forall a . (SolverConfig -> RetryLog SummarizedMessage SolverFailure a)
                          -> SolverConfig
                          -> ConflictSet
                          -> ConflictMap
-                         -> RetryLog String SolverFailure a
+                         -> RetryLog SummarizedMessage SolverFailure a
 tryToMinimizeConflictSet runSolver sc cs cm =
     foldl (\r v -> retryNoSolution r $ tryToRemoveOneVar v)
           (fromProgress $ Fail $ ExhaustiveSearch cs cm)
@@ -249,14 +269,14 @@ tryToMinimizeConflictSet runSolver sc cs cm =
     tryToRemoveOneVar :: Var QPN
                       -> ConflictSet
                       -> ConflictMap
-                      -> RetryLog String SolverFailure a
+                      -> RetryLog SummarizedMessage SolverFailure a
     tryToRemoveOneVar v smallestKnownCS smallestKnownCM
         -- Check whether v is still present, because it may have already been
         -- removed in a previous solver rerun.
       | not (v `CS.member` smallestKnownCS) =
           fromProgress $ Fail $ ExhaustiveSearch smallestKnownCS smallestKnownCM
       | otherwise =
-        continueWith ("Trying to remove variable " ++ varStr ++ " from the "
+        continueWith (mkErrorMsg $ "Trying to remove variable " ++ varStr ++ " from the "
                       ++ "conflict set.") $
         retry (runSolver sc') $ \case
             err@(ExhaustiveSearch cs' _)
@@ -268,14 +288,14 @@ tryToMinimizeConflictSet runSolver sc cs cm =
                                   ++ "conflict set."
                   in -- Use the new conflict set, even if v wasn't removed,
                      -- because other variables may have been removed.
-                     failWith (msg ++ " Continuing with " ++ showCS cs' ++ ".") err
+                     failWith (mkErrorMsg $ msg ++ " Continuing with " ++ showCS cs' ++ ".") err
               | otherwise ->
-                  failWith ("Failed to find a smaller conflict set. The new "
+                  failWith (mkErrorMsg $ "Failed to find a smaller conflict set. The new "
                              ++ "conflict set is not a subset of the previous "
                              ++ "conflict set: " ++ showCS cs') $
                   ExhaustiveSearch smallestKnownCS smallestKnownCM
             BackjumpLimitReached ->
-                failWith "Reached backjump limit while minimizing conflict set."
+                failWith (mkErrorMsg "Reached backjump limit while minimizing conflict set.")
                          BackjumpLimitReached
       where
         varStr = "\"" ++ showVar v ++ "\""
@@ -290,9 +310,9 @@ tryToMinimizeConflictSet runSolver sc cs cm =
 
     -- Like 'retry', except that it only applies the input function when the
     -- backjump limit has not been reached.
-    retryNoSolution :: RetryLog step SolverFailure done
-                    -> (ConflictSet -> ConflictMap -> RetryLog step SolverFailure done)
-                    -> RetryLog step SolverFailure done
+    retryNoSolution :: RetryLog SummarizedMessage SolverFailure done
+                    -> (ConflictSet -> ConflictMap -> RetryLog SummarizedMessage SolverFailure done)
+                    -> RetryLog SummarizedMessage SolverFailure done
     retryNoSolution lg f = retry lg $ \case
         ExhaustiveSearch cs' cm' -> f cs' cm'
         BackjumpLimitReached     -> fromProgress (Fail BackjumpLimitReached)

cabal-install-solver/src/Distribution/Solver/Modular/Log.hs

@@ -7,10 +7,12 @@ import Prelude ()
 import Distribution.Solver.Compat.Prelude
 
 import Distribution.Solver.Types.Progress
-
-import Distribution.Solver.Modular.Dependency
-import Distribution.Solver.Modular.Message
+    ( Progress(Done, Fail), foldProgress, SummarizedMessage )
+import Distribution.Solver.Modular.ConflictSet
+    ( ConflictMap, ConflictSet )
 import Distribution.Solver.Modular.RetryLog
+    ( RetryLog, toProgress, fromProgress )
+import Distribution.Solver.Modular.Message (Message, summarizeMessages)
 
 -- | Information about a dependency solver failure.
 data SolverFailure =
@@ -22,10 +24,10 @@ data SolverFailure =
 -- 'keepLog'), for efficiency.
 displayLogMessages :: Bool
                    -> RetryLog Message SolverFailure a
-                   -> RetryLog String SolverFailure a
+                   -> RetryLog SummarizedMessage SolverFailure a
 displayLogMessages keepLog lg = fromProgress $
     if keepLog
-    then showMessages progress
+    then summarizeMessages progress
     else foldProgress (const id) Fail Done progress
   where
     progress = toProgress lg