Adding an explicit pgmc flag for interaction with GHC

Author: zlonast

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

@@ -81,10 +81,10 @@ import Distribution.Types.GivenComponent
 import Distribution.Types.LocalBuildInfo
 import Distribution.Types.TargetInfo
 import Distribution.Types.UnitId
+import Distribution.Types.Version
 import Distribution.Utils.NubList (NubListR, toNubListR)
 import Distribution.Utils.Path
 import Distribution.Verbosity
-import Distribution.Version (Version)
 import Language.Haskell.Extension
 import System.Directory (listDirectory)
 import System.Environment (getEnv)
@@ -514,6 +514,16 @@ componentJsGhcOptions verbosity lbi bi clbi odir filename =
     , ghcOptExtra = hcOptions GHC bi
     }
 
+-- Applies options only if the GHC version is greater than or
+-- equal to the given one.
+ghcOptionsSince :: Monoid a => Version -> Compiler -> a -> a
+ghcOptionsSince ver comp options =
+  case compilerCompatVersion GHC comp of
+    Just v
+      | v >= ver -> options
+      | otherwise -> mempty
+    Nothing -> mempty
+
 componentGhcOptions
   :: VerbosityLevel
   -> LocalBuildInfo
@@ -587,6 +597,15 @@ componentGhcOptions verbosity lbi bi clbi odir =
         , -- Unsupported extensions have already been checked by configure
           ghcOptExtensions = toNubListR $ usedExtensions bi
         , ghcOptExtensionMap = Map.fromList . compilerExtensions $ (compiler lbi)
+        , -- https://gitlab.haskell.org/ghc/ghc/-/merge_requests/6949
+          -- Only pass -pie, -no-pie when linking the value of -pgmc
+          -- does not matter when checking for the workaround of
+          -- https://gitlab.haskell.org/ghc/ghc/-/issues/15319
+          ghcOptCcProgram =
+            ghcOptionsSince
+              (mkVersion [9, 4])
+              (compiler lbi)
+              (maybeToFlag $ programPath <$> lookupProgram gccProgram (withPrograms lbi))
         }
   where
     exe_paths =

cabal-testsuite/PackageTests/FFI/ForeignOptsPgmc/Main.hs

@@ -0,0 +1,16 @@
+{-# LANGUAGE ForeignFunctionInterface #-}
+
+module Main where
+
+import Foreign.C (CInt (..))
+
+foreign import ccall "pgmclib.h meaning_of_life_pgmc"
+  meaning_of_life_pgmc :: IO CInt
+
+main :: IO ()
+main = do
+  secret <- meaning_of_life_pgmc
+  -- The value 66 comes from __TESTOPT_PGMC__ - see cc-wrapper.sh.
+  if (secret == 66)
+    then putStrLn ("The secret is " ++ show secret)
+    else error ("Expected value 66, got " ++ show secret)

cabal-testsuite/PackageTests/FFI/ForeignOptsPgmc/README.md

@@ -0,0 +1,7 @@
+# ForeignOptsPgmc
+
+This test case asserts that cabal passes the `-pgmc` GHC option to override the C compiler program.
+
+The cabal file sets `ghc-options: -pgmc scripts/cc-wrapper.sh`, pointing GHC at a shell script wrapper (`scripts/cc-wrapper.sh`) instead of the system C compiler. The wrapper adds `-D__TESTOPT_PGMC__=66` to every compilation and then delegates to the real `cc`. The C source requires `__TESTOPT_PGMC__` to be defined; if the wrapper is not used as the C compiler, the build fails with a `#error`.
+
+This test is skipped on Windows (no POSIX shell).

cabal-testsuite/PackageTests/FFI/ForeignOptsPgmc/cabal.out

@@ -0,0 +1,10 @@
+# cabal v2-build
+Resolving dependencies...
+Build profile: -w ghc-<GHCVER> -O1
+In order, the following will be built:
+ - foreign-opts-pgmc-0.1 (exe:foreign-opts-pgmc-exe) (first run)
+Configuring executable 'foreign-opts-pgmc-exe' for foreign-opts-pgmc-0.1...
+Preprocessing executable 'foreign-opts-pgmc-exe' for foreign-opts-pgmc-0.1...
+Building executable 'foreign-opts-pgmc-exe' for foreign-opts-pgmc-0.1...
+# foreign-opts-pgmc foreign-opts-pgmc-exe
+The secret is 66

cabal-testsuite/PackageTests/FFI/ForeignOptsPgmc/cabal.project

@@ -0,0 +1 @@
+packages: .

cabal-testsuite/PackageTests/FFI/ForeignOptsPgmc/cabal.test.hs

@@ -0,0 +1,10 @@
+import Test.Cabal.Prelude
+
+main = do
+  skipIfWindows "requires a POSIX shell script as the C compiler wrapper"
+  cabalTest $ do
+    skipUnlessGhcVersion ">= 9.4"
+    cwd <- fmap testCurrentDir getTestEnv
+    let wrapper = cwd </> "scripts/cc-wrapper.sh"
+    cabal "v2-build" ["foreign-opts-pgmc-exe"]
+    withPlan $ runPlanExe "foreign-opts-pgmc" "foreign-opts-pgmc-exe" []

cabal-testsuite/PackageTests/FFI/ForeignOptsPgmc/cbits/pgmclib.c

@@ -0,0 +1,9 @@
+#include "pgmclib.h"
+
+#ifndef __TESTOPT_PGMC__
+#error "Did not get required __TESTOPT_PGMC__ from the -pgmc wrapper"
+#endif
+
+int meaning_of_life_pgmc() {
+    return __TESTOPT_PGMC__;
+}

cabal-testsuite/PackageTests/FFI/ForeignOptsPgmc/cbits/pgmclib.h

@@ -0,0 +1,6 @@
+#ifndef PGMCLIB_H
+#define PGMCLIB_H
+
+int meaning_of_life_pgmc();
+
+#endif

cabal-testsuite/PackageTests/FFI/ForeignOptsPgmc/foreign-opts-pgmc.cabal

@@ -0,0 +1,12 @@
+cabal-version:       2.2
+name:                foreign-opts-pgmc
+version:             0.1
+build-type:          Simple
+
+executable foreign-opts-pgmc-exe
+  main-is:             Main.hs
+  build-depends:       base
+  default-language:    Haskell2010
+  include-dirs:        cbits
+  c-sources:           cbits/pgmclib.c
+  ghc-options:         -pgmc scripts/cc-wrapper.sh

cabal-testsuite/PackageTests/FFI/ForeignOptsPgmc/scripts/cc-wrapper.sh

@@ -0,0 +1,4 @@
+#!/bin/sh
+# Wrapper around cc that adds -D__TESTOPT_PGMC__=66 to every compilation.
+# Used by the ForeignOptsPgmc test to verify that -pgmc selects this wrapper.
+exec cc -D__TESTOPT_PGMC__=66 "$@"