haskellPackages.iserv-proxy: use in subprocess mode when doing cross (#508035)

pkgs/development/haskell-modules/generic-builder.nix

@@ -46,14 +46,8 @@ let
           in
           buildPackages.writeShellScriptBin ("iserv-wrapper" + lib.optionalString enableProfiling "-prof") ''
             set -euo pipefail
-            PORT=$((5000 + $RANDOM % 5000))
             ${lib.optionalString stdenv.hostPlatform.isWindows "export WINEDEBUG=-all WINEPREFIX=$TMP"}
-            (>&2 echo "---> Starting interpreter on port $PORT")
-            ${emulator} ${hostProxy} tmp $PORT &
-            RISERV_PID="$!"
-            trap "kill $RISERV_PID" EXIT # Needs cleanup when building without sandbox
-            ${buildProxy} $@ 127.0.0.1 "$PORT"
-            (>&2 echo "---> killing interpreter...")
+            ${buildProxy} $@ --pipe ${emulator} ${hostProxy} tmp --stdio
           '';
 
         # GHC will add `-prof` to the external interpreter when doing a profiled build.
@@ -262,8 +256,7 @@ in
   __onlyPropagateKnownPkgConfigModules ? false,
   enableExternalInterpreter ?
     isCross && crossSupport.canProxyTH && crossSupport.needsExternalInterpreterSetup,
-  # iserv-proxy needs local network access
-  __darwinAllowLocalNetworking ? stdenv.hostPlatform.isDarwin && enableExternalInterpreter,
+  __darwinAllowLocalNetworking ? false,
 }@args:
 
 assert editedCabalFile != null -> revision != null;

pkgs/development/tools/haskell/iserv-proxy/default.nix

@@ -15,14 +15,14 @@
 }:
 mkDerivation {
   pname = "iserv-proxy";
-  version = "9.3-unstable-2026-02-04";
+  version = "9.3-unstable-2026-04-08";
 
   # https://github.com/stable-haskell/iserv-proxy/pull/1
   src = fetchFromGitHub {
     owner = "stable-haskell";
     repo = "iserv-proxy";
-    rev = "91ef7ffdeedfb141a4d69dcf9e550abe3e1160c6";
-    hash = "sha256-x6QYupvHZM7rRpVO4AIC5gUWFprFQ59A95FPC7/Owjg";
+    rev = "3f7b2815307c20a0dfd816bdf4a39ab86af3e0d4";
+    hash = "sha256-10x8/G0x3eR/++XRHPx4MBuqlnc6+N+ajIxXyLkG+nU=";
   };
 
   isLibrary = true;