python3Packages.pybind11: work around clang check

This is required for the upcoming clang 16 bump for Darwin. clang 16
defaults to C++17, which results in aligned allocations in pybind11.
These are supported in libc++ with the 10.12 SDK, but clang has a
hard-coded check for 10.13.

pkgs/development/python-modules/pybind11/default.nix

@@ -12,6 +12,7 @@
 , pytestCheckHook
 , libxcrypt
 , makeSetupHook
+, darwin
 }: let
   setupHook = makeSetupHook {
     name = "pybind11-setup-hook";
@@ -22,6 +23,19 @@
       pythonSitePackages = "${python}/${python.sitePackages}";
     };
   } ./setup-hook.sh;
+
+  # clang 16 defaults to C++17, which results in the use of aligned allocations by pybind11.
+  # libc++ supports aligned allocations via `posix_memalign`, which is available since 10.6,
+  # but clang has a check hard-coded requiring 10.13 because that’s when Apple first shipped a
+  # support for C++17 aligned allocations on macOS.
+  # Tell clang we’re targeting 10.13 on x86_64-darwin while continuing to use the default SDK.
+  stdenv' = if stdenv.isDarwin && stdenv.isx86_64
+    then python.stdenv.override (oldStdenv: {
+      buildPlatform = oldStdenv.buildPlatform // { darwinMinVersion = "10.13"; };
+      targetPlatform = oldStdenv.targetPlatform // { darwinMinVersion = "10.13"; };
+      hostPlatform = oldStdenv.hostPlatform // { darwinMinVersion = "10.13"; };
+    })
+    else python.stdenv;
 in buildPythonPackage rec {
   pname = "pybind11";
   version = "2.11.1";
@@ -41,6 +55,8 @@ in buildPythonPackage rec {
   buildInputs = lib.optionals (pythonOlder "3.9") [ libxcrypt ];
   propagatedBuildInputs = [ setupHook ];
 
+  stdenv = stdenv';
+
   dontUseCmakeBuildDir = true;
 
   # Don't build tests if not needed, read the doInstallCheck value at runtime