Use exact GHC versions rather than major-version #736

ChangeLog.md

@@ -1,5 +1,9 @@
 ## 0.1.3.1
 
+Major changes:
+
+* You now have more control over how GHC versions are matched, e.g. "use exactly this version," "use the specified minor version, but allow patches," or "use the given minor version or any later minor in the given major release." The default has switched from allowing newer later minor versions to a specific minor version allowing patches. For more information, see [#736](https://github.com/commercialhaskell/stack/issues/736) and [#784](https://github.com/commercialhaskell/stack/pull/784).
+
 Bug fixes:
 
 * Ignore disabled executables [#763](https://github.com/commercialhaskell/stack/issues/763)

src/Stack/Build/Source.hs

@@ -143,10 +143,13 @@ parseTargetsFromBuildOpts needTargets bopts = do
             ResolverSnapshot snapName -> do
                 $logDebug $ "Checking resolver: " <> renderSnapName snapName
                 loadMiniBuildPlan snapName
-            ResolverGhc ghc ->
-                return
-                    MiniBuildPlan
-                    { mbpGhcVersion = fromMajorVersion ghc
+            ResolverCompiler _ -> do
+                -- We ignore the resolver version, as it might be
+                -- GhcMajorVersion, and we want the exact version
+                -- we're using.
+                version <- asks (envConfigGhcVersion . getEnvConfig)
+                return MiniBuildPlan
+                    { mbpGhcVersion = version
                     , mbpPackages = Map.empty
                     }
             ResolverCustom _ url -> do

src/Stack/BuildPlan.hs

@@ -735,7 +735,8 @@ data CustomSnapshot = CustomSnapshot
 instance FromJSON CustomSnapshot where
     parseJSON = withObject "CustomSnapshot" $ \o -> CustomSnapshot
         <$> ((o .: "compiler") >>= (\t -> maybe (fail $ "Invalid compiler: " ++ T.unpack t) return $ do
-                t' <- T.stripPrefix "ghc-" t
-                parseVersionFromString $ T.unpack t'))
+                cv <- parseCompilerVersion t
+                case cv of
+                    GhcVersion v -> return v))
         <*> o .: "packages"
         <*> o .:? "flags" .!= Map.empty

src/Stack/Config.hs

@@ -137,6 +137,8 @@ configFromConfigMonoid configStackRoot mproject configMonoid@ConfigMonoid{..} =
 
          configImage = Image.imgOptsFromMonoid configMonoidImageOpts
 
+         configCompilerCheck = fromMaybe MatchMinor configMonoidCompilerCheck
+
      origEnv <- getEnvOverride configPlatform
      let configEnvOverride _ = return origEnv
 
@@ -281,20 +283,20 @@ loadBuildConfig mproject config stackRoot mresolver = do
                     (MiniConfig manager config)
     let project = project' { projectResolver = resolver }
 
-    ghcVersion <-
+    wantedCompiler <-
         case projectResolver project of
             ResolverSnapshot snapName -> do
                 mbp <- runReaderT (loadMiniBuildPlan snapName) miniConfig
-                return $ mbpGhcVersion mbp
-            ResolverGhc m -> return $ fromMajorVersion m
+                return $ GhcVersion $ mbpGhcVersion mbp
             ResolverCustom _name url -> do
                 mbp <- runReaderT (parseCustomMiniBuildPlan stackYamlFP url) miniConfig
-                return $ mbpGhcVersion mbp
+                return $ GhcVersion $ mbpGhcVersion mbp
+            ResolverCompiler wantedCompiler -> return wantedCompiler
 
     return BuildConfig
         { bcConfig = config
         , bcResolver = projectResolver project
-        , bcGhcVersionExpected = ghcVersion
+        , bcWantedCompiler = wantedCompiler
         , bcPackageEntries = projectPackages project
         , bcExtraDeps = projectExtraDeps project
         , bcStackYaml = stackYamlFP

src/Stack/Fetch.hs

@@ -335,14 +335,14 @@ fuzzyLookupCandidates (PackageIdentifier name ver) caches =
     if null sameMajor then Nothing else Just (map fst sameMajor)
   where
     sameMajor = filter (\(PackageIdentifier _ v, _) ->
-                             getMajorVersion ver == getMajorVersion v)
+                             toMajorVersion ver == toMajorVersion v)
                        sameIdentCaches
     sameIdentCaches = maybe biggerFiltered
                             (\z -> (zeroIdent, z) : biggerFiltered)
                             zeroVer
     biggerFiltered = takeWhile (\(PackageIdentifier n _, _) -> name == n)
                                (Map.toList bigger)
-    zeroIdent = PackageIdentifier name (fromMajorVersion (MajorVersion 0 0))
+    zeroIdent = PackageIdentifier name $(mkVersion "0.0")
     (_, zeroVer, bigger) = Map.splitLookup zeroIdent caches
 
 -- | Figure out where to fetch from.

src/Stack/Init.hs

@@ -148,7 +148,7 @@ getDefaultResolver cabalfps gpds initOpts =
             mpair <-
                 case resolver of
                     ResolverSnapshot name -> findBuildPlan gpds [name]
-                    ResolverGhc _ -> return Nothing
+                    ResolverCompiler _ -> return Nothing
                     ResolverCustom _ _ -> return Nothing
             case mpair of
                 Just (snap, flags) ->
@@ -157,7 +157,7 @@ getDefaultResolver cabalfps gpds initOpts =
         MethodSolver -> do
             (ghcVersion, extraDeps) <- cabalSolver (map parent cabalfps) Map.empty []
             return
-                ( ResolverGhc ghcVersion
+                ( ResolverCompiler (GhcVersion ghcVersion)
                 , Map.filter (not . Map.null) $ fmap snd extraDeps
                 , fmap fst extraDeps
                 )