From ce41a5e3f005dad05f1ddfcca8f94bc77fe12881 Mon Sep 17 00:00:00 2001
From: Takeshi KOMIYA <i.tkomiya@gmail.com>
Date: Sun, 9 Jan 2022 04:04:31 +0900
Subject: [PATCH] Close #10055: sphinx-build: Create directories when `-w`
 option given

---
 CHANGES             | 1 +
 sphinx/cmd/build.py | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/CHANGES b/CHANGES
index 6ce3e51f3d0..7e41bb99ef0 100644
--- a/CHANGES
+++ b/CHANGES
@@ -37,6 +37,7 @@ Features added
   checking in matched documents.
 * #9793: sphinx-build: Allow to use the parallel build feature in macOS on macOS
   and Python3.8+
+* #10055: sphinx-build: Create directories when ``-w`` option given
 * #9993: std domain: Allow to refer an inline target (ex. ``_`target name```)
   via :rst:role:`ref` role
 * #9391: texinfo: improve variable in ``samp`` role
diff --git a/sphinx/cmd/build.py b/sphinx/cmd/build.py
index 77e3cd44fa5..8de24a364f0 100644
--- a/sphinx/cmd/build.py
+++ b/sphinx/cmd/build.py
@@ -16,6 +16,7 @@
 import pdb
 import sys
 import traceback
+from os import path
 from typing import IO, Any, List
 
 from docutils.utils import SystemMessage
@@ -28,6 +29,7 @@
 from sphinx.util import Tee, format_exception_cut_frames, save_traceback
 from sphinx.util.console import color_terminal, nocolor, red, terminal_safe  # type: ignore
 from sphinx.util.docutils import docutils_namespace, patch_docutils
+from sphinx.util.osutil import abspath, ensuredir
 
 
 def handle_exception(app: Sphinx, args: Any, exception: BaseException, stderr: IO = sys.stderr) -> None:  # NOQA
@@ -240,6 +242,8 @@ def build_main(argv: List[str] = sys.argv[1:]) -> int:
 
     if warning and args.warnfile:
         try:
+            warnfile = abspath(args.warnfile)
+            ensuredir(path.dirname(warnfile))
             warnfp = open(args.warnfile, 'w')
         except Exception as exc:
             parser.error(__('cannot open warning file %r: %s') % (