wip(build): target macOS 12

flake.nix

@@ -18,7 +18,7 @@
               # against the system version of ncurses. This ensures emacs' TUI
               # works out of the box without the user having to manually set
               # TERMINFO in the shell before launching emacs.
-              apple-sdk
+              apple-sdk_12
               autoconf
               cairo
               clang
@@ -68,6 +68,8 @@
 
             shellHook = ''
             export CC=clang
+            export MACOSX_DEPLOYMENT_TARGET="12.0"
+            export DEVELOPER_DIR="${pkgs.apple-sdk_12}"
             export NIX_LIBGCCJIT_VERSION="${pkgs.libgccjit.version}"
             export NIX_LIBGCCJIT_ROOT="${pkgs.libgccjit.outPath}"
           '';