Enable colored output for argparse help in Python 3.14 (#19021)

Support for colored output was just merged in cpython. Maybe a bit early
to add it here already but it doesn't hurt either.

| Current | With color |
| --- | --- |
| <img width="1058" alt="Without color"
src="https://github.com/user-attachments/assets/48edae3e-9361-4af0-aff6-7931410bcd2e"
/> | <img width="944" alt="With color"
src="https://github.com/user-attachments/assets/38e64082-0321-4d36-a5fe-4d59c6eddc31"
/> |

The color output can be disable using various environment variables.

https://docs.python.org/3.14/using/cmdline.html#using-on-controlling-color

Author: cdce8p

mypy/dmypy/client.py

@@ -36,6 +36,9 @@ def __init__(self, prog: str, **kwargs: Any) -> None:
 parser = argparse.ArgumentParser(
     prog="dmypy", description="Client for mypy daemon mode", fromfile_prefix_chars="@"
 )
+if sys.version_info >= (3, 14):
+    parser.color = True  # Set as init arg in 3.14
+
 parser.set_defaults(action=None)
 parser.add_argument(
     "--status-file", default=DEFAULT_STATUS_FILE, help="status file to retrieve daemon details"

mypy/main.py

@@ -491,6 +491,8 @@ def process_options(
         stdout=stdout,
         stderr=stderr,
     )
+    if sys.version_info >= (3, 14):
+        parser.color = True  # Set as init arg in 3.14
 
     strict_flag_names: list[str] = []
     strict_flag_assignments: list[tuple[str, bool]] = []

mypy/stubgen.py

@@ -1851,6 +1851,8 @@ def parse_options(args: list[str]) -> Options:
     parser = argparse.ArgumentParser(
         prog="stubgen", usage=HEADER, description=DESCRIPTION, fromfile_prefix_chars="@"
     )
+    if sys.version_info >= (3, 14):
+        parser.color = True  # Set as init arg in 3.14
 
     parser.add_argument(
         "--ignore-errors",

mypy/stubtest.py

@@ -2084,6 +2084,8 @@ def parse_options(args: list[str]) -> _Arguments:
     parser = argparse.ArgumentParser(
         description="Compares stubs to objects introspected from the runtime."
     )
+    if sys.version_info >= (3, 14):
+        parser.color = True  # Set as init arg in 3.14
     parser.add_argument("modules", nargs="*", help="Modules to test")
     parser.add_argument(
         "--concise",