nixpkgs/pkgs/development/python-modules/gyp/no-xcode.patch

--- gyp-old/pylib/gyp/xcode_emulation.py	1980-01-02 00:00:00.000000000 -0600
+++ gyp/pylib/gyp/xcode_emulation.py	2020-08-02 20:24:24.871322520 -0500
@@ -1407,10 +1407,10 @@
       raise GypError("xcodebuild returned unexpected results")
   except:
     version = CLTVersion()
-    if version:
+    if version and re.match(r'(\d\.\d\.?\d*)', version):
       version = re.match(r'(\d\.\d\.?\d*)', version).groups()[0]
     else:
-      raise GypError("No Xcode or CLT version detected!")
+      version = '7.0.0'
     # The CLT has no build information, so we return an empty string.
     version_list = [version, '']
   version = version_list[0]
@@ -1667,7 +1667,8 @@
     sdk_root = xcode_settings._SdkRoot(configuration)
     if not sdk_root:
       sdk_root = xcode_settings._XcodeSdkPath('')
-    env['SDKROOT'] = sdk_root
+    if not sdk_root:
+      env['SDKROOT'] = ''
 
   if not additional_settings:
     additional_settings = {}