darwin.libffi: check that the trampoline dylib is built correctly

pkgs/os-specific/darwin/by-name/li/libffi/package.nix

@@ -3,6 +3,9 @@
   autoreconfHook,
   dejagnu,
   mkAppleDerivation,
+  runCommand,
+  dyld,
+  python3,
   stdenv,
   testers,
   texinfo,
@@ -12,6 +15,10 @@
   doCheck ? !(stdenv.hostPlatform.isStatic),
 }:
 
+let
+  python3-with-macholib = python3.withPackages (pkgs: [ pkgs.macholib ]);
+in
+
 mkAppleDerivation (finalAttrs: {
   releaseName = "libffi";
 
@@ -94,6 +101,32 @@ mkAppleDerivation (finalAttrs: {
       pkg-config = testers.hasPkgConfigModules {
         package = finalAttrs.finalPackage;
       };
+      # Done as a passthru test to avoid pulling dyld into the Darwin bootstrap just for `dyld_info`.
+      # `dyld_info` is needed because `check-trampolines-dylib.py` does not check chained fixups.
+      check-trampolines-dylib =
+        runCommand "check-trampolines-dylib"
+          {
+            inherit (finalAttrs) src version;
+
+            nativeBuildInputs = [
+              dyld
+              python3-with-macholib
+            ];
+            buildInputs = [ finalAttrs.finalPackage ];
+
+            meta = {
+              description = "Test whether the libffi trampoline was built correctly and works on Darwin.";
+              inherit (finalAttrs.meta) license platforms;
+            };
+          }
+          ''
+            runPhase unpackPhase
+            trampolineDylib=${lib.escapeShellArg (lib.getLib finalAttrs.finalPackage)}/lib/libffi-trampolines.dylib
+            patchShebangs check-trampolines-dylib.py
+            ./check-trampolines-dylib.py "$trampolineDylib"
+            dyld_info -fixups "$trampolineDylib" | grep -v "chained fixups, seg_count exceeds number of segments"
+            touch "$out"
+          '';
     };
   };