From bc498fdfa482dfe796e3a12ac8f9d71913930740 Mon Sep 17 00:00:00 2001
From: Sylvain Henry <sylvain@haskus.fr>
Date: Thu, 4 Nov 2021 18:23:31 +0100
Subject: Bignum: expose backendName (#20495)

---
 libraries/ghc-bignum/changelog.md                  | 4 ++++
 libraries/ghc-bignum/ghc-bignum.cabal              | 2 +-
 libraries/ghc-bignum/src/GHC/Num/Backend/Check.hs  | 7 +++++++
 libraries/ghc-bignum/src/GHC/Num/Backend/FFI.hs    | 4 ++++
 libraries/ghc-bignum/src/GHC/Num/Backend/GMP.hs    | 4 ++++
 libraries/ghc-bignum/src/GHC/Num/Backend/Native.hs | 5 +++++
 6 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/libraries/ghc-bignum/changelog.md b/libraries/ghc-bignum/changelog.md
index 68f98d3adc..015721d40b 100644
--- a/libraries/ghc-bignum/changelog.md
+++ b/libraries/ghc-bignum/changelog.md
@@ -1,5 +1,9 @@
 # Changelog for `ghc-bignum` package
 
+## 1.3
+
+- Expose backendName
+
 ## 1.2
 
 - Moved naturalToDouble# and naturalToFloat# to `base` package
diff --git a/libraries/ghc-bignum/ghc-bignum.cabal b/libraries/ghc-bignum/ghc-bignum.cabal
index 468c2a042a..59ba847272 100644
--- a/libraries/ghc-bignum/ghc-bignum.cabal
+++ b/libraries/ghc-bignum/ghc-bignum.cabal
@@ -1,6 +1,6 @@
 cabal-version:       2.0
 name:                ghc-bignum
-version:             1.2
+version:             1.3
 synopsis:            GHC BigNum library
 license:             BSD3
 license-file:        LICENSE
diff --git a/libraries/ghc-bignum/src/GHC/Num/Backend/Check.hs b/libraries/ghc-bignum/src/GHC/Num/Backend/Check.hs
index b23fd1cb21..00930a62bf 100644
--- a/libraries/ghc-bignum/src/GHC/Num/Backend/Check.hs
+++ b/libraries/ghc-bignum/src/GHC/Num/Backend/Check.hs
@@ -12,6 +12,7 @@
 -- | Check Native implementation against another backend
 module GHC.Num.Backend.Check where
 
+import GHC.CString
 import GHC.Prim
 import GHC.Types
 import GHC.Num.WordArray
@@ -27,6 +28,12 @@ import qualified GHC.Num.Backend.Selected as Other
 
 default ()
 
+-- | ghc-bignum backend name
+backendName :: [Char]
+backendName = unpackAppendCString# "check-"# Other.backendName
+  -- we don't have (++) at our disposal, so we directly use
+  -- `unpackAppendCString#`
+
 bignat_compare
    :: WordArray#
    -> WordArray#
diff --git a/libraries/ghc-bignum/src/GHC/Num/Backend/FFI.hs b/libraries/ghc-bignum/src/GHC/Num/Backend/FFI.hs
index 21d74ee3e4..30fcc576cb 100644
--- a/libraries/ghc-bignum/src/GHC/Num/Backend/FFI.hs
+++ b/libraries/ghc-bignum/src/GHC/Num/Backend/FFI.hs
@@ -25,6 +25,10 @@ import {-# SOURCE #-} GHC.Num.Integer
 
 default ()
 
+-- | ghc-bignum backend name
+backendName :: [Char]
+backendName = "ffi"
+
 -- | Compare two non-zero BigNat of the same length
 --
 -- Return:
diff --git a/libraries/ghc-bignum/src/GHC/Num/Backend/GMP.hs b/libraries/ghc-bignum/src/GHC/Num/Backend/GMP.hs
index 3fd4394bcf..48f5f8a90e 100644
--- a/libraries/ghc-bignum/src/GHC/Num/Backend/GMP.hs
+++ b/libraries/ghc-bignum/src/GHC/Num/Backend/GMP.hs
@@ -32,6 +32,10 @@ import {-# SOURCE #-} GHC.Num.Natural
 
 default ()
 
+-- | ghc-bignum backend name
+backendName :: [Char]
+backendName = "gmp"
+
 ----------------------------------------------------------------------------
 -- type definitions
 
diff --git a/libraries/ghc-bignum/src/GHC/Num/Backend/Native.hs b/libraries/ghc-bignum/src/GHC/Num/Backend/Native.hs
index 723096544a..da08c55dd1 100644
--- a/libraries/ghc-bignum/src/GHC/Num/Backend/Native.hs
+++ b/libraries/ghc-bignum/src/GHC/Num/Backend/Native.hs
@@ -30,6 +30,11 @@ import GHC.Types
 
 default ()
 
+-- | ghc-bignum backend name
+backendName :: [Char]
+backendName = "native"
+
+
 count_words_bits :: Word# -> (# Word#, Word# #)
 count_words_bits n = (# nw, nb #)
    where
-- 
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