doc: conf.py: build directory from environment

Get the output directory from environment variables instead of
attempting to reparse the CLI arguments, as these can actually refer
to a program other than `sphinx-build` (for example `sphinx-autobuild`).

Signed-off-by: Jordan Yates <jordan@embeint.com>

doc/CMakeLists.txt

@@ -45,6 +45,7 @@ endif()
 set(SPHINX_ENV
   DOXYGEN_EXECUTABLE=${DOXYGEN_EXECUTABLE}
   DOT_EXECUTABLE=${DOXYGEN_DOT_EXECUTABLE}
+  DOCS_HTML_DIR=${CMAKE_CURRENT_BINARY_DIR}/html
 )
 
 if(DEFINED ENV{ZEPHYR_DOXYGEN_OVERLAY})

doc/conf.py

@@ -7,11 +7,8 @@ from pathlib import Path
 import re
 import textwrap
 
-from sphinx.cmd.build import get_parser
-
-args = get_parser().parse_args()
 ZEPHYR_BASE = Path(__file__).resolve().parents[1]
-ZEPHYR_BUILD = Path(args.outputdir).resolve()
+ZEPHYR_BUILD = Path(os.environ.get("DOCS_HTML_DIR")).resolve()
 
 # Add the '_extensions' directory to sys.path, to enable finding Sphinx
 # extensions within.