Use response files for ghc invocations

Before this change, `cabal` could fail with the following error message
when building very large Haskell packages:

```
ghc: createProcess: posix_spawnp: resource exhausted (Argument list too long)
```

This is because when the number of modules or dependencies grows large
enough, then the `ghc` command line can potentially exceed the
`ARG_MAX` command line length limit.

However, `ghc` supports response files in order to work around these
sorts of command line length limitations, so this change enables the
use of those response files.

Note that this requires taking a special precaution to not pass RTS
options to the response file because there's no way that `ghc` can
support RTS options via the response file.  The reason why is because
the Haskell runtime processes these options (not `ghc`), so if you
store the RTS options in the response file then `ghc`'s command line
parser won't know what to do with them.

This means that `ghc` commands can still potentially fail if the RTS
options get long enough, but this is less likely to occur in practice
since RTS options tend to be significantly smaller than non-RTS
options.

This also requires skipping the response file if the first argument
is `--interactive`.  See the corresponding code comment which explains
why in more detail.

Co-Authored-By: Gabriella Gonzales <GenuineGabriella@gmail.com>

Cabal-tests/tests/UnitTests/Distribution/Utils/Structured.hs

@@ -34,4 +34,4 @@ md5CheckGenericPackageDescription proxy = md5Check proxy
 
 md5CheckLocalBuildInfo :: Proxy LocalBuildInfo -> Assertion
 md5CheckLocalBuildInfo proxy = md5Check proxy
-    0x94827844fdb1afedee525061749fb16f
+    0xff829d7b383bcccb8192c5a61176c2e0

Cabal/src/Distribution/Simple/GHC.hs

@@ -627,6 +627,8 @@ startInterpreter verbosity progdb comp platform packageDBs = do
           }
   checkPackageDbStack verbosity comp packageDBs
   (ghcProg, _) <- requireProgram verbosity ghcProgram progdb
+  -- This doesn't pass source file arguments to GHC, so we don't have to worry
+  -- about using a response file here.
   runGHC verbosity ghcProg comp platform Nothing replOpts
 
 -- -----------------------------------------------------------------------------

Cabal/src/Distribution/Simple/GHC/Build/ExtraSources.hs

@@ -176,7 +176,17 @@ buildExtraSources
         sources = viewSources (targetComponent targetInfo)
         comp = compiler lbi
         platform = hostPlatform lbi
-        runGhcProg = runGHC verbosity ghcProg comp platform
+        responseFileDir = coerceSymbolicPath buildTargetDir
+        runGhcProg =
+          runGHCWithResponseFile
+            "ghc.rsp"
+            Nothing
+            responseFileDir
+            verbosity
+            ghcProg
+            comp
+            platform
+            mbWorkDir
 
         buildAction :: SymbolicPath Pkg File -> IO ()
         buildAction sourceFile = do
@@ -219,7 +229,7 @@ buildExtraSources
               compileIfNeeded :: GhcOptions -> IO ()
               compileIfNeeded opts = do
                 needsRecomp <- checkNeedsRecompilation mbWorkDir sourceFile opts
-                when needsRecomp $ runGhcProg mbWorkDir opts
+                when needsRecomp $ runGhcProg opts
 
           createDirectoryIfMissingVerbose verbosity True (i odir)
           case targetComponent targetInfo of
@@ -251,6 +261,7 @@ buildExtraSources
                 DynWay -> compileIfNeeded sharedSrcOpts
                 ProfWay -> compileIfNeeded profSrcOpts
                 ProfDynWay -> compileIfNeeded profSharedSrcOpts
+
       -- build any sources
       if (null sources || componentIsIndefinite clbi)
         then return mempty

Cabal/src/Distribution/Simple/GHC/Build/Link.hs

@@ -98,6 +98,7 @@ linkOrLoadComponent
       clbi = buildCLBI pbci
       isIndef = componentIsIndefinite clbi
       mbWorkDir = mbWorkDirLBI lbi
+      responseFileDir = coerceSymbolicPath buildTargetDir
 
       -- See Note [Symbolic paths] in Distribution.Utils.Path
       i = interpretSymbolicPathLBI lbi
@@ -188,10 +189,26 @@ linkOrLoadComponent
         -- exports.
         when (case component of CLib lib -> null (allLibModules lib clbi); _ -> False) $
           warn verbosity "No exposed modules"
-        runReplOrWriteFlags ghcProg lbi replFlags replOpts_final (pkgName (PD.package pkg_descr)) target
+        runReplOrWriteFlags
+          ghcProg
+          lbi
+          replFlags
+          replOpts_final
+          (pkgName (PD.package pkg_descr))
+          target
+          responseFileDir
       _otherwise ->
         let
-          runGhcProg = runGHC verbosity ghcProg comp platform mbWorkDir
+          runGhcProg =
+            runGHCWithResponseFile
+              "ghc.rsp"
+              Nothing
+              responseFileDir
+              verbosity
+              ghcProg
+              comp
+              platform
+              mbWorkDir
           platform = hostPlatform lbi
           comp = compiler lbi
           get_rpaths ways =
@@ -721,8 +738,9 @@ runReplOrWriteFlags
   -> GhcOptions
   -> PackageName
   -> TargetInfo
+  -> SymbolicPath Pkg (Dir Response)
   -> IO ()
-runReplOrWriteFlags ghcProg lbi rflags ghcOpts pkg_name target =
+runReplOrWriteFlags ghcProg lbi rflags ghcOpts pkg_name target responseFileDir =
   let bi = componentBuildInfo $ targetComponent target
       clbi = targetCLBI target
       comp = compiler lbi
@@ -731,7 +749,17 @@ runReplOrWriteFlags ghcProg lbi rflags ghcOpts pkg_name target =
       mbWorkDir = mbWorkDirLBI lbi
       verbosity = fromFlag $ setupVerbosity common
    in case replOptionsFlagOutput (replReplOptions rflags) of
-        NoFlag -> runGHC verbosity ghcProg comp platform mbWorkDir ghcOpts
+        NoFlag ->
+          runGHCWithResponseFile
+            "ghc.rsp"
+            Nothing
+            responseFileDir
+            verbosity
+            ghcProg
+            comp
+            platform
+            mbWorkDir
+            ghcOpts
         Flag out_dir -> do
           let uid = componentUnitId clbi
               this_unit = prettyShow uid

Cabal/src/Distribution/Simple/GHC/Build/Modules.hs

@@ -137,20 +137,29 @@ buildHaskellModules numJobs ghcProg mbMainFile inputModules buildTargetDir neede
       | BuildRepl{} <- what = True
       | otherwise = False
 
-  -- TODO: do we need to put hs-boot files into place for mutually recursive
-  -- modules?  FIX: what about exeName.hi-boot?
+    -- TODO: do we need to put hs-boot files into place for mutually recursive
+    -- modules?  FIX: what about exeName.hi-boot?
 
-  -- Determine if program coverage should be enabled and if so, what
-  -- '-hpcdir' should be.
-  let isCoverageEnabled = if isLib then libCoverage lbi else exeCoverage lbi
-      hpcdir way
-        | forRepl = mempty -- HPC is not supported in ghci
-        | isCoverageEnabled = Flag $ Hpc.mixDir (coerceSymbolicPath $ coerceSymbolicPath buildTargetDir </> extraCompilationArtifacts) way
-        | otherwise = mempty
+    -- Determine if program coverage should be enabled and if so, what
+    -- '-hpcdir' should be.
+    isCoverageEnabled = if isLib then libCoverage lbi else exeCoverage lbi
+    hpcdir way
+      | forRepl = mempty -- HPC is not supported in ghci
+      | isCoverageEnabled = Flag $ Hpc.mixDir (coerceSymbolicPath $ coerceSymbolicPath buildTargetDir </> extraCompilationArtifacts) way
+      | otherwise = mempty
 
-  let
     mbWorkDir = mbWorkDirLBI lbi
-    runGhcProg = runGHC verbosity ghcProg comp platform mbWorkDir
+    responseFileDir = coerceSymbolicPath buildTargetDir
+    runGhcProg =
+      runGHCWithResponseFile
+        "ghc.rsp"
+        Nothing
+        responseFileDir
+        verbosity
+        ghcProg
+        comp
+        platform
+        mbWorkDir
     platform = hostPlatform lbi
 
     (hsMains, scriptMains) =

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

@@ -16,6 +16,7 @@ module Distribution.Simple.Program.GHC
   , ghcInvocation
   , renderGhcOptions
   , runGHC
+  , runGHCWithResponseFile
   , packageDbArgsDb
   , normaliseGhcArgs
   ) where
@@ -32,8 +33,10 @@ import Distribution.Simple.Compiler
 import Distribution.Simple.Flag
 import Distribution.Simple.GHC.ImplInfo
 import Distribution.Simple.Program.Find (getExtraPathEnv)
+import Distribution.Simple.Program.ResponseFile
 import Distribution.Simple.Program.Run
 import Distribution.Simple.Program.Types
+import Distribution.Simple.Utils (defaultTempFileOptions)
 import Distribution.System
 import Distribution.Types.ComponentId
 import Distribution.Types.ParStrat
@@ -42,6 +45,7 @@ import Distribution.Utils.Path
 import Distribution.Verbosity
 import Distribution.Version
 
+import GHC.IO.Encoding (TextEncoding)
 import Language.Haskell.Extension
 
 import Data.List (stripPrefix)
@@ -52,7 +56,7 @@ import qualified Data.Set as Set
 normaliseGhcArgs :: Maybe Version -> PackageDescription -> [String] -> [String]
 normaliseGhcArgs (Just ghcVersion) PackageDescription{..} ghcArgs
   | ghcVersion `withinRange` supportedGHCVersions =
-      argumentFilters . filter simpleFilters . filterRtsOpts $ ghcArgs
+      argumentFilters . filter simpleFilters . filterRtsArgs $ ghcArgs
   where
     supportedGHCVersions :: VersionRange
     supportedGHCVersions = orLaterVersion (mkVersion [8, 0])
@@ -162,18 +166,9 @@ normaliseGhcArgs (Just ghcVersion) PackageDescription{..} ghcArgs
       flagArgumentFilter
         ["-ghci-script", "-H", "-interactive-print"]
 
-    filterRtsOpts :: [String] -> [String]
-    filterRtsOpts = go False
-      where
-        go :: Bool -> [String] -> [String]
-        go _ [] = []
-        go _ ("+RTS" : opts) = go True opts
-        go _ ("-RTS" : opts) = go False opts
-        go isRTSopts (opt : opts) = addOpt $ go isRTSopts opts
-          where
-            addOpt
-              | isRTSopts = id
-              | otherwise = (opt :)
+    -- \| Remove RTS arguments from a list.
+    filterRtsArgs :: [String] -> [String]
+    filterRtsArgs = snd . splitRTSArgs
 
     simpleFilters :: String -> Bool
     simpleFilters =
@@ -646,6 +641,63 @@ runGHC verbosity ghcProg comp platform mbWorkDir opts = do
   runProgramInvocation verbosity
     =<< ghcInvocation verbosity ghcProg comp platform mbWorkDir opts
 
+runGHCWithResponseFile
+  :: FilePath
+  -> Maybe TextEncoding
+  -> SymbolicPath Pkg (Dir Response)
+  -> Verbosity
+  -> ConfiguredProgram
+  -> Compiler
+  -> Platform
+  -> Maybe (SymbolicPath CWD (Dir Pkg))
+  -> GhcOptions
+  -> IO ()
+runGHCWithResponseFile fileNameTemplate encoding responseFileDir verbosity ghcProg comp platform maybeWorkDir opts = do
+  invocation <- ghcInvocation verbosity ghcProg comp platform maybeWorkDir opts
+
+  -- Don't use response files if the first argument is `--interactive`, for
+  -- two related reasons.
+  --
+  -- `hie-bios` relies on a hack to intercept the command-line that `Cabal`
+  -- supplies to `ghc`.  Specifically, `hie-bios` creates a script around
+  -- `ghc` that detects if the first option is `--interactive` and if so then
+  -- instead of running `ghc` it prints the command-line that `ghc` was given
+  -- instead of running the command:
+  --
+  -- https://github.com/haskell/hie-bios/blob/ce863dba7b57ded20160b4f11a487e4ff8372c08/wrappers/cabal#L7
+  --
+  -- … so we can't store that flag in the response file, otherwise that will
+  -- break.  However, even if we were to add a special-case to keep that flag
+  -- out of the response file things would still break because `hie-bios`
+  -- stores the arguments to `ghc` that the wrapper script outputs and reuses
+  -- them later.  That breaks if you use a response file because it will
+  -- store an argument like `@…/ghc36000-0.rsp` which is a temporary path
+  -- that no longer exists after the wrapper script completes.
+  --
+  -- The work-around here is that we don't use a response file at all if the
+  -- first argument (and only the first argument) to `ghc` is
+  -- `--interactive`.  This ensures that `hie-bios` and all downstream
+  -- utilities (e.g. `haskell-language-server`) continue working.
+  case progInvokeArgs invocation of
+    "--interactive" : _ ->
+      runProgramInvocation verbosity invocation
+    args -> do
+      let (rtsArgs, otherArgs) = splitRTSArgs args
+
+      withResponseFile
+        verbosity
+        defaultTempFileOptions
+        maybeWorkDir
+        responseFileDir
+        fileNameTemplate
+        encoding
+        otherArgs
+        $ \responseFile -> do
+          let newInvocation =
+                invocation{progInvokeArgs = ('@' : responseFile) : rtsArgs}
+
+          runProgramInvocation verbosity newInvocation
+
 ghcInvocation
   :: Verbosity
   -> ConfiguredProgram
@@ -959,6 +1011,26 @@ packageDbArgs implInfo
   | flagPackageConf implInfo = packageDbArgsConf
   | otherwise = packageDbArgsDb
 
+-- | Split a list of command-line arguments into RTS arguments and non-RTS
+-- arguments.
+splitRTSArgs :: [String] -> ([String], [String])
+splitRTSArgs args =
+  let addRTSArg arg ~(rtsArgs, nonRTSArgs) = (arg : rtsArgs, nonRTSArgs)
+      addNonRTSArg arg ~(rtsArgs, nonRTSArgs) = (rtsArgs, arg : nonRTSArgs)
+
+      go _ [] = ([], [])
+      go isRTSArg (arg : rest) =
+        case arg of
+          "+RTS" -> addRTSArg arg $ go True rest
+          "-RTS" -> addRTSArg arg $ go False rest
+          "--RTS" -> (arg : rest, [])
+          "--" -> (arg : rest, [])
+          _ ->
+            if isRTSArg
+              then addRTSArg arg $ go isRTSArg rest
+              else addNonRTSArg arg $ go isRTSArg rest
+   in go False args
+
 -- -----------------------------------------------------------------------------
 -- Boilerplate Monoid instance for GhcOptions