From ec40b0453730d7555bccccbd94c8dab9e36f3dd6 Mon Sep 17 00:00:00 2001
From: Randy Eckenrode <randy@largeandhighquality.com>
Date: Mon, 2 Sep 2024 10:07:54 -0400
Subject: [PATCH] darwin.libunwind: improve compatibility with libunwind
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Darwin uses the system unwinder, which is based on the LLVM unwinder.
While it’s mostly API-compatible with libunwind, some packages expect to
find it using `pkg-config`. This package provides a compatible file to
allow those packages to use the system unwinder on Darwin.
---
 pkgs/os-specific/darwin/libunwind/default.nix | 28 +++++++++++++++++++
 pkgs/top-level/darwin-packages.nix            |  2 ++
 2 files changed, 30 insertions(+)
 create mode 100644 pkgs/os-specific/darwin/libunwind/default.nix

diff --git a/pkgs/os-specific/darwin/libunwind/default.nix b/pkgs/os-specific/darwin/libunwind/default.nix
new file mode 100644
index 000000000000..a19bfc6864e3
--- /dev/null
+++ b/pkgs/os-specific/darwin/libunwind/default.nix
@@ -0,0 +1,28 @@
+{
+  lib,
+  apple-sdk,
+  stdenvNoCC,
+}:
+
+stdenvNoCC.mkDerivation (finalAttrs: {
+  pname = "libunwind";
+  inherit (apple-sdk) version;
+
+  # No `-lunwind` is provided becuase you get it automatically from linking with libSystem.
+  # It’s also not possible to link libunwind directly, otherwise. Darwin requires going through libSystem.
+  buildCommand = ''
+    mkdir -p "$out/lib/pkgconfig"
+    cat <<EOF > "$out/lib/pkgconfig/libunwind.pc"
+    Name: libunwind
+    Description: An implementation of the HP libunwind interface
+    Version: ${finalAttrs.version}
+    EOF
+  '';
+
+  meta = {
+    description = "Compatibility package for libunwind on Darwin";
+    maintainers = lib.teams.darwin.members;
+    platforms = lib.platforms.darwin;
+    pkgConfigModules = [ "libunwind" ];
+  };
+})
diff --git a/pkgs/top-level/darwin-packages.nix b/pkgs/top-level/darwin-packages.nix
index 693742fd952f..3725ae98324e 100644
--- a/pkgs/top-level/darwin-packages.nix
+++ b/pkgs/top-level/darwin-packages.nix
@@ -169,6 +169,8 @@ impure-cmds // appleSourcePackages // stubs // {
     propagatedBuildInputs = [ pkgs.darwin.print-reexports ];
   } ../os-specific/darwin/print-reexports/setup-hook.sh;
 
+  libunwind = callPackage ../os-specific/darwin/libunwind { };
+
   sigtool = callPackage ../os-specific/darwin/sigtool { };
 
   signingUtils = callPackage ../os-specific/darwin/signing-utils { };