Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC Commits: afa5c414 by mangoiv at 2026-10-05T15:42:57-04:00 hadrian: Persist the used flavour name in the build root (#20650) This executes the idea proposed in #20650, teaching Hadrian to persist the flavour used to build a build root. This both makes use of multiple build roots more ergonomic (as the user no longer needs to repeat themselves) and avoids a tiresome foot-gun (forgetting to specify a flavour, often wholly invalidating a build root). Closes #20650. Co-authored-by: Sylvain Henry <sylvain@haskus.fr> - - - - - 4b89c7cc by mangoiv at 2026-10-05T15:42:58-04:00 configure: fix sed script and subst tooldir script Fixes #27672 Adds sanity checking for SUBST_TOOLDIR Metric Decrease: LinkableUsage01 MultiLayerModulesTH_OneShot T10547 T12234 T12425 T13035 T13820 T18140 T18730 T18923 T9198 TcPlugin_RewritePerf mhu-perf - - - - - aee5101e by Hannes Siebenhandl at 2026-10-05T15:42:59-04:00 Prepend in-memory unit database for backpack The packageDbFlags are stored in reverse order. Thus, prepending will ensure that the in-memory unit database is the last item on the unit database stack. Further, the in-memory unit database needs to be able to shadow units from earlier unit databases in the unit database stack. Moreover, a `-clear-package-db` would remove the in-memory database if it weren't the last item on the stack. Closes #27835 - - - - - 11 changed files: - + changelog.d/hadrian-persist-flavour - changelog.d/unit-index - compiler/GHC/Driver/Backpack.hs - distrib/configure.ac.in - hadrian/doc/flavours.md - hadrian/src/Rules.hs - hadrian/src/Settings.hs - m4/subst_tooldir.m4 - + testsuite/tests/backpack/should_compile/T27835.bkp - + testsuite/tests/backpack/should_compile/T27835.stderr - testsuite/tests/backpack/should_compile/all.T Changes: ===================================== changelog.d/hadrian-persist-flavour ===================================== @@ -0,0 +1,7 @@ +section: packaging +synopsis: Hadrian now persists the flavour name in the build root. When + rebuilding, the previously used flavour is automatically restored, removing + the need to re-specify it on every invocation and avoiding accidental build + root invalidation. +issues: #20650 +mrs: !7017 ===================================== changelog.d/unit-index ===================================== @@ -1,7 +1,7 @@ section: compiler synopsis: Use global ``UnitIndex`` to deduplicate ``UnitInfo``s over multiple home units -issues: #27500 #26423 #27748 #27834 -mrs: !16115 !16598 !16743 +issues: #27500 #26423 #27748 #27834 #27835 +mrs: !16115 !16598 !16743 !16748 description: { The ``UnitState`` used to be duplicated for all ``HomeUnitEnv``, not sharing any of the ``UnitInfo``s. ===================================== compiler/GHC/Driver/Backpack.hs ===================================== @@ -441,9 +441,11 @@ addInMemoryDatabase dflags u = do } let uic = hscUIC hsc_env liftIO $ cacheExternalUnitDatabase uic newdb - -- added at the end because ordering matters + -- Ordering matters here! We prepend the new unit database, because 'packageDBFlags' + -- works like a stack, where what's on top takes precedence over what's below (same as right-to-left when given at the CLI). + -- The new db needs highest precedence to overwrite any other in-memory units that potentially occur in the dbs below it. pure dflags - { packageDBFlags = packageDBFlags dflags ++ [PackageDB (PkgDbPath (unitDatabasePath newdb))] + { packageDBFlags = PackageDB (PkgDbPath (unitDatabasePath newdb)) : packageDBFlags dflags } -- | Register a new virtual unit database containing a single unit ===================================== distrib/configure.ac.in ===================================== @@ -103,7 +103,7 @@ AC_ARG_ENABLE(distro-toolchain, AC_SUBST([EnableDistroToolchain]) if test "$HostOS" = "mingw32" -a "$EnableDistroToolchain" = "NO"; then - FP_SETUP_WINDOWS_TOOLCHAIN([$hardtop/mingw/], [\$\$topdir/../mingw/]) + FP_SETUP_WINDOWS_TOOLCHAIN([$hardtop/mingw/], [\$topdir/../mingw/]) fi ===================================== hadrian/doc/flavours.md ===================================== @@ -3,7 +3,14 @@ Hadrian supports a few predefined _build flavours_, i.e. collections of build settings that fully define a GHC build (see `src/Flavour.hs`). Users can add their own build flavours if need be, as described -[here](https://gitlab.haskell.org/ghc/ghc/blob/master/hadrian/doc/user-settings.md#...). +[here](https://gitlab.haskell.org/ghc/ghc/blob/master/hadrian/doc/user-settings.md#...) or modify existing flavours using the flavour transformers notion seem below. + +The flavour to be used for a build root can be specified on the command-line +via the `--flavour` flag. Moreover, this flavour name is saved in the build +root; future invocations of Hadrian without a `--flavour` flag will default to +the last-used flavour. + +See `Note [Persisting the flavour]` in `hadrian/src/Settings.hs` ## Arguments ===================================== hadrian/src/Rules.hs ===================================== @@ -129,6 +129,7 @@ packageRules = do buildRules :: Rules () buildRules = do + Settings.flavourFileRules Rules.BinaryDist.bindistRules Rules.Generate.copyRules Rules.Generate.generateRules ===================================== hadrian/src/Settings.hs ===================================== @@ -1,10 +1,14 @@ +{-# LANGUAGE TupleSections #-} +{-# LANGUAGE TypeFamilies #-} + module Settings ( getExtraArgs, getArgs, getLibraryWays, getRtsWays, flavour, knownPackages, findPackageByName, unsafeFindPackageByName, unsafeFindPackageByPath, isLibrary, stagePackages, getBignumBackend, completeSetting, queryBuildTarget, queryHostTarget, queryBuild, queryHost, - queryArch, queryOS, queryVendor + queryArch, queryOS, queryVendor, + flavourFileRules ) where import CommandLine @@ -58,6 +62,56 @@ hadrianFlavours = , ghcInGhciFlavour, validateFlavour, slowValidateFlavour ] +{- +Note [Persisting the flavour] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Passing the flavour on the command-line means the user must consistently pass +the same --flavour flag to all Hadrian invocations on a particular build root. +Forgetting even once can result in a full rebuild of the tree. + +To avoid this we persist the flavour name in the build root itself +(specifically, in `<build root>/flavour`). We refer to this file when looking +up the active flavour, defaulting to it if the user does not specify a flavour +name explicitly. +-} + +-- | Oracle query type for the active flavour name. +-- See Note [Persisting the flavour]. +newtype FlavourName = FlavourName () + deriving (Binary, Eq, Hashable, NFData, Show) +type instance RuleResult FlavourName = String + +flavourFileRules :: Rules () +flavourFileRules = do + root <- buildRootRules + + -- Cache the flavour name lookup for the whole Shake run. + -- alwaysRerun ensures the oracle re-executes on every new invocation so + -- that a changed --flavour flag is never ignored due to a stale cross-run + -- cache entry (CLI args are not tracked as Shake dependencies). + -- See Note [Persisting the flavour]. + void $ addOracleCache $ \(FlavourName _) -> do + alwaysRerun + let flavourFile = root -/- "flavour" + cmdFlavour >>= \case + Just nm -> do + putBuild $ "Flavour: " ++ nm + liftIO $ writeFile flavourFile nm + return nm + Nothing -> do + exists <- doesFileExist flavourFile + if exists + then do nm <- liftIO $ readFile flavourFile + putBuild $ "Flavour: " ++ nm ++ " (cached from last build, override by passing --flavour=... explicitly)" + return nm + else return userDefaultFlavour + +-- | Lookup the requested flavour name, referring to the persistent flavour +-- file saved from the previous Hadrian execution if not specified. +-- The result is cached for the whole Shake run via the 'FlavourName' oracle. +getFlavourName :: Action String +getFlavourName = askOracle (FlavourName ()) + -- | This action looks up a flavour with the name given on the -- command line with @--flavour@, defaulting to 'userDefaultFlavour' -- when no explicit @--flavour@ is passed. It then applies any @@ -66,7 +120,7 @@ hadrianFlavours = -- syntax. See Note [Hadrian settings] at the bottom of this file. flavour :: Action Flavour flavour = do - flavourName <- fromMaybe userDefaultFlavour <$> cmdFlavour + flavourName <- getFlavourName when ("quickest" `isPrefixOf` flavourName) $ fail $ "The `quickest` flavour has been deprecated. Use `quick` instead.\n" ++ "Skip building dynamic libraries with `quick+no_dynamic_libs`\n" ===================================== m4/subst_tooldir.m4 ===================================== @@ -41,5 +41,5 @@ dnl ghc-toolchain. # See Note [How we configure the bundled windows toolchain] AC_DEFUN([SUBST_TOOLDIR], [ - sed -i.bkp $1 's%'"$mingw_prefix"'%'"$mingw_install_prefix"'%g' + sed -i.bkp 's%'"$mingw_prefix"'%'"$mingw_install_prefix"'%g' $1 ]) ===================================== testsuite/tests/backpack/should_compile/T27835.bkp ===================================== @@ -0,0 +1,11 @@ +unit p where + module P where + p :: Int + p = 42 + +unit q where + dependency p + module Q where + import P + q :: Int + q = p + 1 ===================================== testsuite/tests/backpack/should_compile/T27835.stderr ===================================== @@ -0,0 +1,7 @@ +[1 of 2] Processing p + Instantiating p + [1 of 1] Compiling P ( p/P.hs, T27835.out/p/P.o ) +[2 of 2] Processing q + Instantiating q + [1 of 1] Including p + [1 of 1] Compiling Q ( q/Q.hs, T27835.out/q/Q.o ) ===================================== testsuite/tests/backpack/should_compile/all.T ===================================== @@ -61,3 +61,4 @@ test('T13250', normal, backpack_compile, ['']) test('T13323', normal, backpack_compile, ['']) test('T20396', normal, backpack_compile, ['']) test('T23424', [ignore_stdout, ignore_stderr], backpack_compile, ['-ddump-rn-trace -ddump-if-trace -ddump-tc-trace']) +test('T27835', normal, backpack_compile, ['-clear-package-db -global-package-db']) View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/c5dc8554c2797282fef4680bf0cacd6... -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/c5dc8554c2797282fef4680bf0cacd6... 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