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Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC

Commits:

c8238375

by Sylvain Henry at 2026-03-06T06:34:23-05:00

Hadrian: deprecate --bignum and automatically enable +native_bignum for JS

Deprecate --bignum=... to select the bignum backend. It's only used to
select the native backend, and this can be done with the +native_bignum
flavour transformer.

Additionally, we automatically enable +native_bignum for the JS target
because the GMP backend isn't supported.

4 changed files:

hadrian/README.md
hadrian/src/CommandLine.hs
hadrian/src/Main.hs
hadrian/src/Settings.hs

Changes:

hadrian/README.md

@@ -101,7 +101,9 @@ Stage2 GHC.
  * `--skip-depends`: skips rebuilding Haskell module dependency files.
 -* `--bignum={native,gmp,check-gmp,ffi}`: choose which bignum implementation to use. The default is `gmp`.
 +* `--bignum={native,gmp,check-gmp,ffi}`: **Deprecated.** Use the `+native_bignum` flavour
 +  transformer instead (e.g. `--flavour=default+native_bignum`). When building for the
 +  JavaScript target, the native bignum backend is enabled automatically.
  * `--color` and `--no-color`: choose whether to use colors when printing build
  progress info. By default, Hadrian tries to determine if the terminal supports

hadrian/src/CommandLine.hs

  module CommandLine (
      optDescrs, cmdLineArgsMap, cmdFlavour, lookupFreeze1, lookupFreeze2, lookupSkipDepends,
 +    lookupBignum,
      cmdBignum, cmdBignumCheck, cmdProgressInfo, cmdCompleteSetting,
      cmdDocsArgs, cmdUnitIdHash, lookupBuildRoot, TestArgs(..), TestSpeed(..), defaultTestArgs,
      cmdPrefix, DocArgs(..), defaultDocArgs
@@ -389,6 +390,9 @@ lookupFreeze2 = freeze2 . lookupExtra defaultCommandLineArgs
  lookupSkipDepends :: Map.HashMap TypeRep Dynamic -> Bool
  lookupSkipDepends = skipDepends . lookupExtra defaultCommandLineArgs
 +lookupBignum :: Map.HashMap TypeRep Dynamic -> Maybe String
 +lookupBignum = bignum . lookupExtra defaultCommandLineArgs
++
  cmdUnitIdHash :: Action Bool
  cmdUnitIdHash = unitIdHash <$> cmdLineArgs

hadrian/src/Main.hs

@@ -34,6 +34,13 @@ main = do
      -- Provide access to command line arguments and some user settings through
      -- Shake's type-indexed map 'shakeExtra'.
      argsMap <- CommandLine.cmdLineArgsMap
 +    case CommandLine.lookupBignum argsMap of
 +      Just _ -> hPutStrLn stderr $ unlines
 +        [ "Warning: --bignum is deprecated."
 +        , "  Use the '+native_bignum' flavour transformer instead (e.g. --flavour=default+native_bignum)."
 +        , "  When building for the JavaScript target, native bignum is now enabled automatically."
 +        ]
 +      Nothing -> return ()
      let extra = insertExtra UserSettings.buildProgressColour
                $ insertExtra UserSettings.successColour
                $ argsMap

hadrian/src/Settings.hs

@@ -30,6 +30,7 @@ import Settings.Flavours.Release
  import Hadrian.Oracles.TextFile
  import GHC.Toolchain.Target
  import GHC.Platform.ArchOS
 +import Oracles.Setting (isJsTarget)
  getExtraArgs :: Args
  getExtraArgs = expr flavour >>= extraArgs
@@ -44,9 +45,7 @@ getRtsWays :: Ways
  getRtsWays = expr flavour >>= rtsWays
  getBignumBackend :: Expr String
 -getBignumBackend = expr $ cmdBignum >>= \case
 -   Nothing -> bignumBackend <$> flavour
 -   Just b  -> pure b
 +getBignumBackend = bignumBackend <$> expr flavour
  getBignumCheck :: Expr Bool
  getBignumCheck = expr $ cmdBignum >>= \case
@@ -90,9 +89,17 @@ flavour = do
        $ "failed to apply key-value settings:\n\t" ++ unlines (map (" - " ++) settingErrs) ++
          "\t   Entries should look something like \"stage1.containers.ghc.hs.opts += -Werror\""
 +    -- Handle --bignum (deprecated) and JS auto-detection
 +    bignumTweak <- cmdBignum >>= \case
 +        Just "native"  -> return useNativeBignum
 +        Just b         -> return $ \f -> f { bignumBackend = b }
 +        Nothing        -> do
 +          js <- isJsTarget
 +          return $ if js then useNativeBignum else id
++
      case parseFlavour flavours flavourTransformers flavourName of
        Left err -> fail err
 -      Right f -> return $ flagsTweak (tweak f)
 +      Right f -> return $ bignumTweak (flagsTweak (tweak f))
  -- TODO: switch to Set Package as the order of packages should not matter?
  -- Otherwise we have to keep remembering to sort packages from time to time.