From 28b8fa6277defccb5ba7a3d754fcf2832a72a7a6 Mon Sep 17 00:00:00 2001
From: Alexander Esgen <alexander.esgen@iohk.io>
Date: Fri, 15 Mar 2024 11:01:55 +0100
Subject: [PATCH 1/3] cardano-git-rev: use just one CPP clause

This helps in a follow-up commit.
---
 cardano-git-rev/src/Cardano/Git/Rev.hs | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/cardano-git-rev/src/Cardano/Git/Rev.hs b/cardano-git-rev/src/Cardano/Git/Rev.hs
index 2e69c1501..5b73e163d 100644
--- a/cardano-git-rev/src/Cardano/Git/Rev.hs
+++ b/cardano-git-rev/src/Cardano/Git/Rev.hs
@@ -35,12 +35,7 @@ gitRev :: Q Exp
 gitRev
   | gitRevEmbed /= zeroRev = textE gitRevEmbed
   | otherwise              =
-#if defined(arm_HOST_ARCH)
-      -- cross compiling to arm fails; due to a linker bug
-      textE zeroRev
-#else
       textE =<< TH.runIO runGitRevParse
-#endif
 
 -- Git revision embedded after compilation using
 -- Data.FileEmbed.injectWith. If nothing has been injected,
@@ -48,8 +43,11 @@ gitRev
 gitRevEmbed :: Text
 gitRevEmbed = Text.pack $ drop 28 $ unsafeDupablePerformIO (peekCStringLen utf8 (c_gitrev, 68))
 
-#if !defined(arm_HOST_ARCH)
 runGitRevParse :: IO Text
+#if defined(arm_HOST_ARCH)
+-- cross compiling to arm fails; due to a linker bug
+runGitRevParse = pure zeroRev
+#else
 runGitRevParse = do
     (exitCode, output, errorMessage) <- readProcessWithExitCode_ "git" ["rev-parse", "--verify", "HEAD"] ""
     case exitCode of

From 314f6182c721ba5cc518396b2603d317d6ffb23c Mon Sep 17 00:00:00 2001
From: Alexander Esgen <alexander.esgen@iohk.io>
Date: Fri, 15 Mar 2024 11:03:50 +0100
Subject: [PATCH 2/3] Perform check for embedded git rev at run time

Previously, it was performed at compile time, where it will always be false as
no rev has been embedded yet.
---
 cardano-git-rev/src/Cardano/Git/Rev.hs | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/cardano-git-rev/src/Cardano/Git/Rev.hs b/cardano-git-rev/src/Cardano/Git/Rev.hs
index 5b73e163d..51b065c57 100644
--- a/cardano-git-rev/src/Cardano/Git/Rev.hs
+++ b/cardano-git-rev/src/Cardano/Git/Rev.hs
@@ -32,10 +32,11 @@ foreign import ccall "&_cardano_git_rev" c_gitrev :: CString
 -- This must be a TH splice to ensure the git commit is captured at build time.
 -- ie called as `$(gitRev)`.
 gitRev :: Q Exp
-gitRev
-  | gitRevEmbed /= zeroRev = textE gitRevEmbed
-  | otherwise              =
-      textE =<< TH.runIO runGitRevParse
+gitRev =
+    [| if
+         | gitRevEmbed /= zeroRev -> gitRevEmbed
+         | otherwise              -> $(textE =<< TH.runIO runGitRevParse)
+    |]
 
 -- Git revision embedded after compilation using
 -- Data.FileEmbed.injectWith. If nothing has been injected,

From 792ff3d96b892617ab29ec46152d36c470be2f7a Mon Sep 17 00:00:00 2001
From: Alexander Esgen <alexander.esgen@iohk.io>
Date: Mon, 18 Mar 2024 11:25:47 +0100
Subject: [PATCH 3/3] cardano-git-rev: only use `TemplateHaskellQuotes`

We don't want to splice something at the top-level in cardano-git-rev, but
rather just provide expressions such users can do that in their projects.
---
 cardano-git-rev/src/Cardano/Git/Rev.hs | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/cardano-git-rev/src/Cardano/Git/Rev.hs b/cardano-git-rev/src/Cardano/Git/Rev.hs
index 51b065c57..f87a24110 100644
--- a/cardano-git-rev/src/Cardano/Git/Rev.hs
+++ b/cardano-git-rev/src/Cardano/Git/Rev.hs
@@ -1,9 +1,15 @@
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE MultiWayIf #-}
 {-# LANGUAGE OverloadedStrings #-}
-{-# LANGUAGE TemplateHaskell #-}
 {-# LANGUAGE ForeignFunctionInterface #-}
 
+#if __GLASGOW_HASKELL__ >= 900
+{-# LANGUAGE TemplateHaskellQuotes #-}
+#else
+-- https://gitlab.haskell.org/ghc/ghc/-/merge_requests/2288
+{-# LANGUAGE TemplateHaskell #-}
+#endif
+
 module Cardano.Git.Rev
   ( gitRev
   ) where