fix: click.Path(resolve_path=True) doesn't always work on Windows

See pallets/click#2466

lektor/cli.py

@@ -11,6 +11,7 @@
 from lektor.cli_utils import extraflag
 from lektor.cli_utils import pass_context
 from lektor.cli_utils import pruneflag
+from lektor.cli_utils import ResolvedPath
 from lektor.cli_utils import validate_language
 from lektor.compat import importlib_metadata as metadata
 from lektor.project import Project
@@ -50,7 +51,7 @@ def cli(ctx, project=None, language=None):
 @click.option(
     "-O",
     "--output-path",
-    type=click.Path(resolve_path=True),
+    type=ResolvedPath(),
     default=None,
     help="The output path.",
 )
@@ -165,7 +166,7 @@ def _build():
 @click.option(
     "-O",
     "--output-path",
-    type=click.Path(resolve_path=True),
+    type=ResolvedPath(),
     default=None,
     help="The output path.",
 )
@@ -205,7 +206,7 @@ def clean_cmd(ctx, output_path, verbosity, extra_flags):
 @click.option(
     "-O",
     "--output-path",
-    type=click.Path(resolve_path=True),
+    type=ResolvedPath(),
     default=None,
     help="The output path.",
 )
@@ -312,7 +313,7 @@ def deploy_cmd(ctx, server, output_path, extra_flags, **credentials):
 @click.option(
     "-O",
     "--output-path",
-    type=click.Path(resolve_path=True),
+    type=ResolvedPath(),
     default=None,
     help="The dev server will build into the same folder as "
     "the build command by default.",

lektor/cli_utils.py

@@ -1,6 +1,10 @@
 # pylint: disable=import-outside-toplevel
+from __future__ import annotations
+
 import json
 import os
+from pathlib import Path
+from typing import Any
 
 import click
 
@@ -127,3 +131,26 @@ def validate_language(ctx, param, value):
     if value is not None and not is_valid_language(value):
         raise click.BadParameter('Unsupported language "%s".' % value)
     return value
+
+
+class ResolvedPath(click.Path):
+    """A click paramter type for a resolved path.
+
+    We could just use ``click.Path(resolve_path=True)`` except that that
+    fails sometimes under Windows running python <= 3.9.
+
+    See https://github.com/pallets/click/issues/2466
+    """
+
+    def __init__(self, writable=False, file_okay=True):
+        super().__init__(
+            resolve_path=True, allow_dash=False, writable=writable, file_okay=file_okay
+        )
+
+    def convert(
+        self, value: Any, param: click.Parameter | None, ctx: click.Context | None
+    ) -> Any:
+        abspath = Path(value).absolute()
+        # fsdecode to ensure that the return value is a str.
+        # (with click<8.0.3 Path.convert will return Path if passed a Path)
+        return os.fsdecode(super().convert(abspath, param, ctx))