Update Hadrian

* support ghc-bignum backend selection in flavours and command-line

* support ghc-bignum "--check" flag (compare results of selected backend
  against results of the native one) in flavours and command-line (e.g.
  pass --bignum=check-gmp" to check the "gmp" backend)

* remove the hack to workaround #15286

* build GMP only when the gmp backend is used

* remove hacks to workaround `text` package flags about integer-*. We
  fix `text` to use ghc-bignum unconditionally in another patch

2 files changed, 8 insertions, 17 deletions

diff --git a/hadrian/doc/make.md b/hadrian/doc/make.md
index b0e19e4721..318b736fa5 100644
--- a/hadrian/doc/make.md
+++ b/hadrian/doc/make.md
@@ -94,17 +94,6 @@ time you fire up a build. This is not possible with the Make build system.
   ```
   See [flavours documentation](https://gitlab.haskell.org/ghc/ghc/blob/master/hadrian/doc/flavours.md) for info on flavours.
 
-- Building with `integer-simple` as the integer library
-
-  ``` sh
-  # Make
-  echo "INTEGER_LIBRARY=integer-simple" >> mk/build.mk
-  make
-
-  # Hadrian
-  build --integer-simple
-  ```
-
 - Freezing the stage 1 GHC compiler
 
   ``` sh
diff --git a/hadrian/doc/user-settings.md b/hadrian/doc/user-settings.md
index 9963bac5ed..ada2b98760 100644
--- a/hadrian/doc/user-settings.md
+++ b/hadrian/doc/user-settings.md
@@ -21,8 +21,10 @@ data Flavour = Flavour {
     args :: Args,
     -- | Build these packages.
     packages :: Stage -> Action [Package],
-    -- | Either 'integerGmp' or 'integerSimple'.
-    integerLibrary :: Action Package,
+    -- | Bignum backend: 'native', 'gmp', 'ffi', etc.
+    bignumBackend :: String,
+    -- | Check bignum backend against native
+    bignumCheck :: Bool,
     -- | Build libraries these ways.
     libraryWays :: Ways,
     -- | Build RTS these ways.
@@ -168,12 +170,12 @@ userPackage = library "user-package"
 You will also need to add `userPackage` to a specific build stage by modifying
 the `packages` setting of the user flavour as otherwise it will not be built.
 
-You can choose which integer library to use when building GHC using the
-`integerLibrary` setting of the build flavour. Possible values are: `integerGmp`
-(default) and `integerSimple`.
+You can choose which Bignum backend to use when buidling GHC using the
+`bignumBackend` setting of the build flavour. Possible values are: `gmp`
+(default), `native` or `ffi`.
 ```haskell
 userFlavour :: Flavour
-userFlavour = defaultFlavour { name = "user", integerLibrary = pure integerSimple }
+userFlavour = defaultFlavour { name = "user", bignumBackend = "native" }
 ```
 
 #### Specifying the final stage to build