Print warning about an issue with mapped network drives on Windows // Issue #3417

Starting with Python 3.8 paths to mapped network drives are resolved
to their real path in the system, e.g.: "Z:\path" becomes "\\path" which
causes weird errors in the default terminal with a message that UNC
paths are not supported

platformio/builder/main.py

@@ -28,7 +28,7 @@ from SCons.Script import DefaultEnvironment  # pylint: disable=import-error
 from SCons.Script import Import  # pylint: disable=import-error
 from SCons.Script import Variables  # pylint: disable=import-error
 
-from platformio import fs
+from platformio import compat, fs
 from platformio.compat import dump_json_to_unicode
 from platformio.managers.platform import PlatformBase
 from platformio.proc import get_pythonexe_path
@@ -120,6 +120,16 @@ env.Replace(
     ],
 )
 
+if (
+    compat.WINDOWS
+    and sys.version_info >= (3, 8)
+    and env["PROJECT_DIR"].startswith("\\\\")
+):
+    click.secho(
+        "There is a known issue with Python 3.8+ and mapped network drives on "
+        "Windows.\nPlease downgrade Python to the latest 3.7. More details at:\n"
+        "https://github.com/platformio/platformio-core/issues/3417", fg="yellow")
+
 if env.subst("$BUILD_CACHE_DIR"):
     if not isdir(env.subst("$BUILD_CACHE_DIR")):
         makedirs(env.subst("$BUILD_CACHE_DIR"))