Merge pull request #10979 from haskell/wip/abi-dev-compiler

Fix parsing AbiTag for development compilers

Author: mergify[bot]

Cabal/src/Distribution/Simple/GHC.hs

@@ -85,7 +85,6 @@ import Prelude ()
 
 import Control.Arrow ((***))
 import Control.Monad (forM_)
-import Data.List (stripPrefix)
 import qualified Data.Map as Map
 import Distribution.CabalSpecVersion
 import Distribution.InstalledPackageInfo (InstalledPackageInfo)
@@ -248,8 +247,14 @@ configure verbosity hcPath hcPkgPath conf0 = do
       compilerId :: CompilerId
       compilerId = CompilerId GHC ghcVersion
 
+      -- The @AbiTag@ is the @Project Unit Id@ but with redundant information from the compiler version removed.
+      -- For development versions of the compiler these look like:
+      -- @Project Unit Id@: "ghc-9.13-inplace"
+      -- @compilerId@: "ghc-9.13.20250413"
+      -- So, we need to be careful to only strip the /common/ prefix.
+      -- In this example, @AbiTag@ is "inplace".
       compilerAbiTag :: AbiTag
-      compilerAbiTag = maybe NoAbiTag AbiTag (Map.lookup "Project Unit Id" ghcInfoMap >>= stripPrefix (prettyShow compilerId <> "-"))
+      compilerAbiTag = maybe NoAbiTag AbiTag (dropWhile (== '-') . stripCommonPrefix (prettyShow compilerId) <$> Map.lookup "Project Unit Id" ghcInfoMap)
 
   let comp =
         Compiler

Cabal/src/Distribution/Simple/Utils.hs

@@ -195,6 +195,7 @@ module Distribution.Simple.Utils
   , unintersperse
   , wrapText
   , wrapLine
+  , stripCommonPrefix
 
     -- * FilePath stuff
   , isAbsoluteOnAnyPlatform
@@ -2062,3 +2063,10 @@ findHookedPackageDesc verbosity mbWorkDir dir = do
 
 buildInfoExt :: String
 buildInfoExt = ".buildinfo"
+
+-- | @stripCommonPrefix xs ys@ gives you @ys@ without the common prefix with @xs@.
+stripCommonPrefix :: String -> String -> String
+stripCommonPrefix (x : xs) (y : ys)
+  | x == y = stripCommonPrefix xs ys
+  | otherwise = y : ys
+stripCommonPrefix _ ys = ys

changelog.d/pr-10979

@@ -0,0 +1,8 @@
+synopsis: Fix parsing the AbiTag with development versions of GHC
+packages: Cabal
+prs: #10979
+issues: #10170
+
+description: {
+- Allow parsing the AbiTag for developmement versions of GHC.
+}