fix: prefer architecture-specific wheels over universal for macOS

This is what poetry also seems to do. It should lead to smaller
downloads if both are available and avoiding universal wheels that are
actually just arm64 or x86_64, which I've seen in the wild.

Author: bouk

lib/pypa.nix

@@ -32,6 +32,8 @@ let
   # PEP-625 only specifies .tar.gz as valid extension but .zip is also fairly widespread.
   matchSdistFileName = match "([^-]+)-(.+)(\.tar\.gz|\.zip)";
 
+  matchMacosTag = match "macosx_([0-9]+)_([0-9]+)_(.+)";
+
   # Tag normalization documented in
   # https://packaging.python.org/en/latest/specifications/platform-compatibility-tags/#details
   normalizedImpls = {
@@ -275,7 +277,7 @@ lib.fix (self: {
     else if hasPrefix "macosx" platformTag then
       (
         let
-          m = match "macosx_([0-9]+)_([0-9]+)_(.+)" platformTag;
+          m = matchMacosTag platformTag;
           major = elemAt m 0;
           minor = elemAt m 1;
           arch = elemAt m 2;
@@ -476,7 +478,6 @@ lib.fix (self: {
             languageTags = filter isPythonTagCompatible file.languageTags;
             # Extract the tag as a number. E.g. "37" is `toInt "37"` and "none"/"any" is 0
             languageTags' = map (tag: if tag == "none" then 0 else toInt tag.version) languageTags;
-
           in
           {
             bestLanguageTag = head (sort (x: y: x > y) languageTags');
@@ -485,6 +486,20 @@ lib.fix (self: {
               && length languageTags > 0
               && lib.any (self.isPlatformTagCompatible platform python.stdenv.cc.libc) file.platformTags;
             inherit file;
+            # Prefer macOS wheels with specific architectures over universal2
+            macArchPreference =
+              let
+                macArchs = filter isString (
+                  map (
+                    tag:
+                    let
+                      m = matchMacosTag tag;
+                    in
+                    if m != null then elemAt m 2 else null
+                  ) file.platformTags
+                );
+              in
+              if any (arch: arch != "universal2") macArchs then 1 else 0;
           }
         ) files;
 
@@ -498,6 +513,7 @@ lib.fix (self: {
           || x.file.version > y.file.version
           || (x.file.buildTag != null && (y.file.buildTag == null || x.file.buildTag > y.file.buildTag))
           || x.bestLanguageTag > y.bestLanguageTag
+          || x.macArchPreference > y.macArchPreference
         ) compatibleFiles;
 
       in

lib/test_pypa.nix

@@ -512,8 +512,8 @@ in
       testZmqCPythonDarwin311 = mkTest {
         input = zmqWheels;
         output = [
-          "pyzmq-24.0.1-cp311-cp311-macosx_10_15_universal2.whl"
           "pyzmq-24.0.1-cp311-cp311-macosx_10_9_x86_64.whl"
+          "pyzmq-24.0.1-cp311-cp311-macosx_10_15_universal2.whl"
         ];
         python = mocks.cpythonDarwin311;
       };