CMake: Fix sphinx build with standalone clang

[tstellar]

Summary

This code is copied from llvm/cmake/config-ix.cmake. Would it be better
to refactor this code and put it in
llvm/cmake/modules/AddSphinxTarget.cmake ?

[tstellar]

Remove redundant find_package(Sphinx)

[mgorny]

See also: D23758, for SphInx + doxygen + relevant options.

[beanz]

I think putting this into AddSphinxTarget.cmake would be a better way to handle it. Also I have one small inline comment.

CMakeLists.txt

177 ↗

(On Diff #94145)

If tis code can be run more than once you also need to add AND NOT TARGET sphinx to the condition here.

[tstellar]

Move most logic into AddSphinxTarget.cmake in the llvm tree.

[tstellar]

Ping.

[beanz]

LGTM.

docs/CMakeLists.txt

if (LLVM_ENABLE_DOXYGEN)
   if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
     install(DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/doxygen/html
       DESTINATION docs/html)
   endif()
 endif()
 endif()
 
 if (LLVM_ENABLE_SPHINX)
-  if (SPHINX_FOUND)
-    include(AddSphinxTarget)
+  if (SPHINX_FOUND)
     if (${SPHINX_OUTPUT_HTML})
       add_sphinx_target(html clang)
       add_custom_command(TARGET docs-clang-html POST_BUILD
         COMMAND ${CMAKE_COMMAND} -E copy
         "${CMAKE_CURRENT_SOURCE_DIR}/LibASTMatchersReference.html"
         "${CMAKE_CURRENT_BINARY_DIR}/html/LibASTMatchersReference.html")
     endif()
     if (${SPHINX_OUTPUT_MAN})
       add_sphinx_target(man clang)
     endif()
   endif()
 endif()