makeBinaryWrapper: add comment

pkgs/build-support/setup-hooks/make-binary-wrapper/default.nix

@@ -15,9 +15,7 @@ makeSetupHook {
     ++ lib.optional (stdenv.isDarwin && stdenv.isAarch64) darwin.cctools;
 
   substitutions = {
-    cc = let
-      san = lib.escapeShellArgs (map (s: "-fsanitize=${s}") sanitizers);
-    in "${cc}/bin/cc ${san}";
+    cc = "${cc}/bin/cc ${lib.escapeShellArgs (map (s: "-fsanitize=${s}") sanitizers)}";
 
     # Extract the function call used to create a binary wrapper from its embedded docstring
     passthru.extractCmd = writeShellScript "extract-binary-wrapper-cmd" ''

pkgs/test/default.nix

@@ -74,6 +74,8 @@ with pkgs;
   makeWrapper = callPackage ./make-wrapper { };
   makeBinaryWrapper = callPackage ./make-binary-wrapper {
     makeBinaryWrapper = pkgs.makeBinaryWrapper.override {
+      # Enable sanitizers in the tests only, to avoid the performance cost in regular usage.
+      # The sanitizers cause errors on aarch64-darwin, see https://github.com/NixOS/nixpkgs/pull/150079#issuecomment-994132734
       sanitizers = pkgs.lib.optionals (! (pkgs.stdenv.isDarwin && pkgs.stdenv.isAarch64))
         [ "undefined" "address" ];
     };