haskell.compiler.ghc94*: backport Cabal bugfix for Paths_ modules

There is a code generation bug in Cabal-3.6.3.0. For packages configured with
--enable-relocatable, Cabal would generate code that doesn't compile.

There isn't an upstream issue, but the issue is described in the commit that
fixed it:
https://github.com/haskell/cabal/commit/6c796218c92f93c95e94d5ec2d077f6956f68e98

It was fixed in Cabal-3.8.*
Backport the fix to the Cabal library that ships with ghc-9.4.4

Cabal 3.8 ships with ghc-9.6, so when 9.6 is released this fix shouldn't be
necessary.

1 files changed, 10 insertions, 0 deletions

diff --git a/pkgs/development/compilers/ghc/9.4.4.nix b/pkgs/development/compilers/ghc/9.4.4.nix
index b9897b0f4d82..508316fc5e72 100644
--- a/pkgs/development/compilers/ghc/9.4.4.nix
+++ b/pkgs/development/compilers/ghc/9.4.4.nix
@@ -189,6 +189,16 @@ stdenv.mkDerivation (rec {
 
   outputs = [ "out" "doc" ];
 
+  patches = [
+    # Don't generate code that doesn't compile when --enable-relocatable is passed to Setup.hs
+    # Can be removed if the Cabal library included with ghc backports the linked fix
+    (fetchpatch {
+      url = "https://github.com/haskell/cabal/commit/6c796218c92f93c95e94d5ec2d077f6956f68e98.patch";
+      stripLen = 1;
+      extraPrefix = "libraries/Cabal/";
+      sha256 = "sha256-yRQ6YmMiwBwiYseC5BsrEtDgFbWvst+maGgDtdD0vAY=";
+    })
+  ];
 
   postPatch = "patchShebangs .";