record Git revision in devel builds

`cabal --version` in such builds will include the Git commit and
branch (if not `master`).

Cabal/Cabal.cabal

@@ -29,6 +29,11 @@ source-repository head
   location: https://github.com/haskell/cabal/
   subdir:   Cabal
 
+flag git-rev
+  description: include Git revision hash in version
+  default: False
+  manual: True
+
 library
   default-language: Haskell2010
   hs-source-dirs: src
@@ -51,6 +56,10 @@ library
   else
     build-depends: unix  >= 2.6.0.0 && < 2.9
 
+  if flag(git-rev)
+    build-depends: githash ^>= 0.1.7.0
+    cpp-options: -DGIT_REV
+
   ghc-options:
     -Wall
     -fno-ignore-asserts

Cabal/src/Distribution/Simple/Utils.hs

@@ -9,6 +9,9 @@
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE RankNTypes #-}
 {-# LANGUAGE ScopedTypeVariables #-}
+#ifdef GIT_REV
+{-# LANGUAGE TemplateHaskell #-}
+#endif
 
 -----------------------------------------------------------------------------
 
@@ -28,6 +31,7 @@
 -- various directory and file functions that do extra logging.
 module Distribution.Simple.Utils
   ( cabalVersion
+  , cabalGitInfo
 
     -- * logging and errors
   , dieNoVerbosity
@@ -287,6 +291,16 @@ import System.IO.Unsafe
 import qualified System.Process as Process
 import qualified Text.PrettyPrint as Disp
 
+#ifdef GIT_REV
+import Data.Either (isLeft)
+import GitHash
+  ( giHash
+  , giBranch
+  , giCommitDate
+  , tGitInfoCwdTry
+  )
+#endif
+
 -- We only get our own version number when we're building with ourselves
 cabalVersion :: Version
 #if defined(BOOTSTRAPPED_CABAL)
@@ -297,6 +311,28 @@ cabalVersion = mkVersion [CABAL_VERSION]
 cabalVersion = mkVersion [3,0]  --used when bootstrapping
 #endif
 
+-- |
+-- `Cabal` Git information. Only filled in if built in a Git tree in
+-- developmnent mode and Template Haskell is available.
+cabalGitInfo :: String
+#ifdef GIT_REV
+cabalGitInfo = concat [ "(commit "
+                      , giHash'
+                      , branchInfo
+                      , ", "
+                      , either (const "") giCommitDate gi'
+                      , ")"
+                      ]
+  where
+    gi' = $$tGitInfoCwdTry
+    giHash' = take 7 . either (const "") giHash $ gi'
+    branchInfo | isLeft gi' = ""
+               | either id giBranch gi' == "master" = ""
+               | otherwise = " on " <> either id giBranch gi'
+#else
+cabalGitInfo = ""
+#endif
+
 -- ----------------------------------------------------------------------------
 -- Exception and logging utils
 

cabal-install/cabal-install.cabal

@@ -39,6 +39,11 @@ Flag lukko
   default:      True
   manual:       True
 
+flag git-rev
+  description: include Git revision hash in version
+  default: False
+  manual: True
+
 common warnings
     ghc-options:
       -Wall
@@ -269,6 +274,9 @@ library
     if impl(ghc >=8.2)
       build-depends: process >= 1.6.15.0
 
+    if flag(git-rev)
+      build-depends: githash ^>= 0.1.7.0
+      cpp-options: -DGIT_REV
 
 executable cabal
     import: warnings, base-dep
@@ -282,6 +290,9 @@ executable cabal
     if os(aix)
         extra-libraries: bsd
 
+    if flag(git-rev)
+      cpp-options: -DGIT_REV
+
     build-depends:
         cabal-install
 

cabal-install/src/Distribution/Client/Main.hs

@@ -173,7 +173,8 @@ import Distribution.Client.Utils
   , relaxEncodingErrors
   )
 import Distribution.Client.Version
-  ( cabalInstallVersion
+  ( cabalInstallGitInfo
+  , cabalInstallVersion
   )
 
 import Distribution.Package (packageId)
@@ -227,7 +228,8 @@ import Distribution.Simple.Program
 import Distribution.Simple.Program.Db (reconfigurePrograms)
 import qualified Distribution.Simple.Setup as Cabal
 import Distribution.Simple.Utils
-  ( cabalVersion
+  ( cabalGitInfo
+  , cabalVersion
   , createDirectoryIfMissingVerbose
   , dieNoVerbosity
   , dieWithException
@@ -413,9 +415,16 @@ mainWorker args = do
       putStrLn $
         "cabal-install version "
           ++ display cabalInstallVersion
+          ++ " "
+          ++ cabalInstallGitInfo
           ++ "\ncompiled using version "
           ++ display cabalVersion
           ++ " of the Cabal library "
+          ++ cabalGitInfo'
+      where
+        cabalGitInfo'
+          | cabalGitInfo == cabalInstallGitInfo = "(in-tree)"
+          | otherwise = cabalGitInfo
 
     commands = map commandFromSpec commandSpecs
     commandSpecs =

cabal-install/src/Distribution/Client/Version.hs

@@ -1,13 +1,51 @@
+{-# LANGUAGE CPP #-}
+#ifdef GIT_REV
+{-# LANGUAGE TemplateHaskell #-}
+#endif
+
 -- | Provides the version number of @cabal-install@.
 module Distribution.Client.Version
   ( cabalInstallVersion
+  , cabalInstallGitInfo
   ) where
 
 import Distribution.Version
 
 import qualified Paths_cabal_install as PackageInfo
 
+#ifdef GIT_REV
+import Data.Either (isLeft)
+import GitHash
+  ( giHash
+  , giBranch
+  , giCommitDate
+  , tGitInfoCwdTry
+  )
+#endif
+
 -- |
 -- This value determines the output of `cabal-install --version`.
 cabalInstallVersion :: Version
 cabalInstallVersion = mkVersion' PackageInfo.version
+
+-- |
+-- `cabal-install` Git information. Only filled in if built in a Git tree in
+-- developmnent mode and Template Haskell is available.
+cabalInstallGitInfo :: String
+#ifdef GIT_REV
+cabalInstallGitInfo = concat [ "(commit "
+                             , giHash'
+                             , branchInfo
+                             , ", "
+                             , either (const "") giCommitDate gi'
+                             , ")"
+                             ]
+  where
+    gi' = $$tGitInfoCwdTry
+    giHash' = take 7 . either (const "") giHash $ gi'
+    branchInfo | isLeft gi' = ""
+               | either id giBranch gi' == "master" = ""
+               | otherwise = " on " <> either id giBranch gi'
+#else
+cabalInstallGitInfo = ""
+#endif

cabal.project

@@ -4,3 +4,11 @@ import: project-cabal/pkgs.config
 import: project-cabal/constraints.config
 
 tests: True
+
+-- if you are developing on a system without TH, use a `cabal.project.local`
+-- to disable this
+package cabal-install
+  flags: +git-rev
+
+package Cabal
+  flags: +git-rev

cabal.release.project

@@ -3,3 +3,10 @@ import: project-cabal/pkgs/install.config
 import: project-cabal/pkgs/tests.config
 
 index-state: hackage.haskell.org 2024-09-06T14:16:40Z
+
+-- never include this or its TH dependency in a release!
+package cabal-install
+  flags: -git-rev
+
+package Cabal
+  flags: -git-rev

cabal.validate.project

@@ -7,3 +7,8 @@ tests: True
 write-ghc-environment-files: never
 program-options
   ghc-options: -Werror
+
+-- if you are developing on a system without TH, use a `cabal.validate.project.local`
+-- to disable this
+package cabal-install
+  flags: +git-rev