Fixup AbiTag logic to deal with <build>_<host>-<abitag>.

Author: angerman

Cabal-syntax/src/Distribution/Compiler.hs

@@ -229,6 +229,7 @@ instance Binary CompilerInfo
 instance Structured CompilerInfo
 instance NFData CompilerInfo where rnf = genericRnf
 
+-- | AbiTag logic
 data AbiTag
   = NoAbiTag
   | AbiTag String

Cabal-syntax/src/Distribution/Types/UnitId.hs

@@ -16,6 +16,7 @@ module Distribution.Types.UnitId
   , newSimpleUnitId
   , mkLegacyUnitId
   , getHSLibraryName
+  , getAbiTag
   ) where
 
 import Distribution.Compat.Prelude
@@ -184,3 +185,17 @@ instance Parsec DefUnitId where
 -- is to ensure that the 'DefUnitId' invariant holds.
 unsafeMkDefUnitId :: UnitId -> DefUnitId
 unsafeMkDefUnitId = DefUnitId
+
+-- | The ABI tag is the part of the unit id that comes after the
+-- last hyphen.  It is used to distinguish between different
+-- versions of the same package that are ABI compatible.
+--
+-- FIXME: ideally this would be part of the proper structure of the
+-- datatype, instead of some heuristic of the string.
+getAbiTag :: HasCallStack => UnitId -> AbiTag
+getAbiTag (UnitId _c s _) = case takeWhile (/= '-') . reverse . fromShortText $ s of
+  [] -> NoAbiTag
+  xs -> AbiTag . reverse $ xs
+getAbiTag (PartialUnitId s) = case takeWhile (/= '-') . reverse . fromShortText $ s of
+  [] -> NoAbiTag
+  xs -> AbiTag . reverse $ xs

Cabal/src/Distribution/Simple/GHC.hs

@@ -249,7 +249,7 @@ configure verbosity hcPath hcPkgPath conf0 = do
       compilerId = CompilerId GHC ghcVersion
 
       compilerAbiTag :: AbiTag
-      compilerAbiTag = maybe NoAbiTag AbiTag (Map.lookup "Project Unit Id" ghcInfoMap >>= stripPrefix (prettyShow compilerId <> "-"))
+      compilerAbiTag = fromMaybe NoAbiTag (getAbiTag . fromString <$> Map.lookup "Project Unit Id" ghcInfoMap)
 
   let comp =
         Compiler