Add Option to sphinx-build for custom conf file location

[• dibya001]

Summary

1 - Sphinx takes an optional "-c" option where the directory containing the configuration file(conf.py) path is provided.
2 - Before this change, there was no way to provide path for conf.py file which may not be stored in source directory.
3 - With this change, we can provide an option if the file is not present in the source directory but present in another directory.
4 - One usecase for this is the source directory contains a conf.py.in which is converted to conf.py under the build folder after appropriate cmake variable substitution

[shankare]

Ping ?

[labath]

I don't know anything about Sphinx. It might be useful to mention in the patch description the motivation for this change.

[• dibya001]

In D86866#2252272, @labath wrote:

I don't know anything about Sphinx. It might be useful to mention in the patch description the motivation for this change.

Updated the patch description.

[tatyana-krasnukha]

Looks reasonable to me.

[xgupta]

ping? need someone to comit?

[tstellar]

Do you still want this committed? If so, can you rebase?

llvm/cmake/modules/AddSphinxTarget.cmake

 
 # Handy function for creating the different Sphinx targets.
 #
 # ``builder`` should be one of the supported builders used by
 # the sphinx-build command.
 #
 # ``project`` should be the project name
 function (add_sphinx_target builder project)
-  cmake_parse_arguments(ARG "" "SOURCE_DIR" "" ${ARGN})
+  cmake_parse_arguments(ARG "" "SOURCE_DIR;CONF_FILE_DIR" "" ${ARGN})
   set(SPHINX_BUILD_DIR "${CMAKE_CURRENT_BINARY_DIR}/${builder}")
   set(SPHINX_DOC_TREE_DIR "${CMAKE_CURRENT_BINARY_DIR}/_doctrees-${project}-${builder}")
   set(SPHINX_TARGET_NAME docs-${project}-${builder})
 
   if (SPHINX_WARNINGS_AS_ERRORS)
     set(SPHINX_WARNINGS_AS_ERRORS_FLAG "-W")
   else()
     set(SPHINX_WARNINGS_AS_ERRORS_FLAG "")
   endif()
 
   if (NOT ARG_SOURCE_DIR)
     set(ARG_SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}")
   endif()
 
+  if (NOT ARG_CONF_FILE_DIR)
+    set(ARG_CONF_FILE_DIR "${CMAKE_CURRENT_SOURCE_DIR}")
+  endif()
+
   add_custom_target(${SPHINX_TARGET_NAME}
                     COMMAND ${SPHINX_EXECUTABLE}
                             -b ${builder}
+                            -c ${ARG_CONF_FILE_DIR}
                             -d "${SPHINX_DOC_TREE_DIR}"
                             -q # Quiet: no output other than errors and warnings.
                             -t builder-${builder} # tag for builder
                             ${SPHINX_WARNINGS_AS_ERRORS_FLAG} # Treat warnings as errors if requested
                             "${ARG_SOURCE_DIR}" # Source
                             "${SPHINX_BUILD_DIR}" # Output
                     COMMENT
                     "Generating ${builder} Sphinx documentation for ${project} into \"${SPHINX_BUILD_DIR}\"")