Patch Cabal to deduplicate arguments to hsc2hs, which otherwise grow above 512K and break GCC

Author: sergv

cabal-hsc2hs-args-patch.diff

@@ -0,0 +1,13 @@
+diff --git a/Cabal/src/Distribution/Simple/PreProcess.hs b/Cabal/src/Distribution/Simple/PreProcess.hs
+index d47dd8035..da158a5a3 100644
+--- a/src/Distribution/Simple/PreProcess.hs
++++ b/src/Distribution/Simple/PreProcess.hs
+@@ -464,7 +464,7 @@ ppHsc2hs bi lbi clbi =
+     -- Returns a list of command line arguments that can either be passed
+     -- directly, or via a response file.
+     genPureArgs :: Version -> ConfiguredProgram -> String -> String -> [String]
+-    genPureArgs hsc2hsVersion gccProg inFile outFile =
++    genPureArgs hsc2hsVersion gccProg inFile outFile = ordNub $
+           -- Additional gcc options
+           [ "--cflag=" ++ opt | opt <- programDefaultArgs  gccProg
+                                     ++ programOverrideArgs gccProg ]

flake.nix

@@ -56,7 +56,9 @@
 
           cabal-install = hsPkgs.callCabal2nix "cabal-install" "${inputs.cabal}/cabal-install" { inherit (final) Cabal cabal-install-solver hackage-security; };
           cabal-install-solver = hsPkgs.callCabal2nix "cabal-install-solver" "${inputs.cabal}/cabal-install-solver" { inherit (final) Cabal; };
-          Cabal = hsPkgs.callCabal2nix "Cabal" "${inputs.cabal}/Cabal" { inherit (final) Cabal-syntax; };
+          Cabal = (hsPkgs.callCabal2nix "Cabal" "${inputs.cabal}/Cabal" { inherit (final) Cabal-syntax; }).overrideAttrs (old: {
+            patches = (old.patches or []) ++ [./cabal-hsc2hs-args-patch.diff];
+          });
           Cabal-syntax = hsPkgs.callCabal2nix "Cabal-syntax" "${inputs.cabal}/Cabal-syntax" { };
           Cabal-described = hsPkgs.callCabal2nix "Cabal-described" "${inputs.cabal}/Cabal-described" { };
           Cabal-QuickCheck = hsPkgs.callCabal2nix "Cabal-QuickCheck" "${inputs.cabal}/Cabal-QuickCheck" { };