fix(Cabal): Do not pass -optJSP to GHC < 9.10.2

Cabal-tests/tests/UnitTests/Distribution/Simple/Program/GHC.hs

@@ -10,8 +10,8 @@ import Distribution.Types.ParStrat
 import Distribution.Simple.Flag
 import Distribution.Simple.Compiler (Compiler(..), CompilerId(..), CompilerFlavor(..), AbiTag(NoAbiTag))
 import Distribution.PackageDescription (emptyPackageDescription)
-import Distribution.Simple.Program.GHC (normaliseGhcArgs, renderGhcOptions, ghcOptNumJobs)
-import Distribution.Version            (mkVersion)
+import Distribution.Simple.Program.GHC (GhcOptions, normaliseGhcArgs, renderGhcOptions, ghcOptNumJobs, ghcOptJSppOptions)
+import Distribution.Version            (mkVersion, Version)
 
 tests :: TestTree
 tests = testGroup "Distribution.Simple.Program.GHC"
@@ -59,9 +59,32 @@ tests = testGroup "Distribution.Simple.Program.GHC"
                   (Platform X86_64 Linux)
                   (mempty { ghcOptNumJobs = Flag (NumJobs (Just 4)) })
             assertListEquals flags ["-j4", "-clear-package-db"]
+        , testCase "JS preprocessor options (GHC >= 9.10.2)" $ do
+            let flags = renderWith (mkVersion [9,12,1])
+                  (mempty { ghcOptJSppOptions = ["-DJS"] })
+            assertBool ("expected -optJSP-DJS in " ++ show flags) ("-optJSP-DJS" `elem` flags)
+        , testCase "JS preprocessor options gated out before GHC 9.10.2" $ do
+            let flags = renderWith (mkVersion [9,10,1])
+                  (mempty { ghcOptJSppOptions = ["-DJS"] })
+            assertBool ("unexpected -optJSP in " ++ show flags) ("-optJSP-DJS" `notElem` flags)
         ]
     ]
 
+-- | Render 'GhcOptions' as GHC arguments for a GHC of the given version.
+renderWith :: Version -> GhcOptions -> [String]
+renderWith ver =
+    renderGhcOptions
+      (Compiler
+          { compilerId = CompilerId GHC ver
+          , compilerAbiTag = NoAbiTag
+          , compilerCompat = []
+          , compilerLanguages = []
+          , compilerExtensions = []
+          , compilerProperties = Map.singleton "Support parallel --make" "YES"
+          , compilerWiredInUnitIds = Nothing
+          })
+      (Platform X86_64 Linux)
+
 assertListEquals :: (Eq a, Show a) => [a] -> [a] -> Assertion
 assertListEquals xs ys
     | xs == ys = return ()

Cabal/src/Distribution/Simple/Program/GHC.hs

@@ -521,7 +521,8 @@ data GhcOptions = GhcOptions
   , ghcOptCppOptions :: [String]
   -- ^ Options to pass through to CPP; the @ghc -optP@ flag.
   , ghcOptJSppOptions :: [String]
-  -- ^ Options to pass through to CPP; the @ghc -optJSP@ flag. @since 3.16.0.0
+  -- ^ Options to pass through to the JavaScript preprocessor; the
+  -- @ghc -optJSP@ flag (GHC >= 9.10.2). @since 3.16.0.0
   , ghcOptCppIncludePath :: NubListR (SymbolicPath Pkg (Dir Include))
   -- ^ Search path for CPP includes like header files; the @ghc -I@ flag.
   , ghcOptCppIncludes :: NubListR (SymbolicPath Pkg File)
@@ -874,7 +875,12 @@ renderGhcOptions comp _platform@(Platform _arch os) opts
 
           ["-I" ++ u dir | dir <- flags ghcOptCppIncludePath]
         , ["-optP" ++ opt | opt <- ghcOptCppOptions opts]
-        , ["-optJSP" ++ opt | opt <- ghcOptJSppOptions opts]
+        , -- The JavaScript preprocessor flag (-optJSP) only exists since GHC
+          -- 9.10.2; passing it to an older GHC is an error.
+          let ghc912 = case compilerCompatVersion GHC comp of
+                Just v -> v >= mkVersion [9, 10, 2]
+                Nothing -> False
+           in ["-optJSP" ++ opt | ghc912, opt <- ghcOptJSppOptions opts]
         , concat
             [ ["-optP-include", "-optP" ++ u inc]
             | inc <- flags ghcOptCppIncludes

changelog.d/jspp-options-ghc-912.md

@@ -0,0 +1,11 @@
+---
+synopsis: Do not pass `-optJSP` to GHC older than 9.10.2
+packages: [Cabal]
+prs: 12398
+significance:
+---
+
+The `jspp-options` field is rendered as `ghc -optJSP<opt>`, but that flag only
+exists since GHC 9.10.2. Passing it to an older GHC made the invocation fail, so
+a package using `jspp-options` could not be built at all with GHC < 9.10.2. The
+options are now omitted when the compiler is older than 9.10.2.