[cmake] Support overriding remaining HTML doc install directories

[mgorny]

Summary

Support overriding the Doxygen & OCamldoc install directories, and provide a more FHS-compliant defaults for both of them. This extends r282240 that added this override for Sphinx-built documentation.

LLVM_INSTALL_DOXYGEN_HTML_DIR and LLVM_INSTALL_OCAMLDOC_HTML_DIR are added, to control the location where Doxygen-generated and OCamldoc-generated HTML docs are installed appropriately. They both specify CMake-style install paths, and therefore can either by relative to the install prefix or absolute.

The new defaults are subdirectories of share/doc/llvm, and replace the previous directories of 'docs/html' and 'docs/ocaml/html' that resulted in creating invalid '/usr/docs' that furthermore lacked proper namespacing for the LLVM package. The new defaults are consistent with the ones used for Sphinx HTML documentation, differing only in the last component. Since the 'html' subdirectory is already used for Sphinx docs, the 'doxygen-html' and 'ocaml-html' directories are used instead.

[beanz]

Small nit below, otherwise LGTM! Thanks!

docs/CMakeLists.txt

99

Can you add a COMPONENT to the install commands, maybe something like "doxygen-html"?

162

Here too.

[mgorny]

Thanks for the review. Added components and committed. I will also prepare a quick PR to add components to the Sphinx-installed documentation.

CMakeLists.txt

 option(LLVM_INCLUDE_GO_TESTS "Include the Go bindings tests in test build targets." ON)
 
 option (LLVM_BUILD_DOCS "Build the llvm documentation." OFF)
 option (LLVM_INCLUDE_DOCS "Generate build targets for llvm documentation." ON)
 option (LLVM_ENABLE_DOXYGEN "Use doxygen to generate llvm API documentation." OFF)
 option (LLVM_ENABLE_SPHINX "Use Sphinx to generate llvm documentation." OFF)
 option (LLVM_ENABLE_OCAMLDOC "Build OCaml bindings documentation." ON)
 
+set(LLVM_INSTALL_DOXYGEN_HTML_DIR "share/doc/llvm/doxygen-html"
+    CACHE STRING "Doxygen-generated HTML documentation install directory")
+set(LLVM_INSTALL_OCAMLDOC_HTML_DIR "share/doc/llvm/ocaml-html"
+    CACHE STRING "OCamldoc-generated HTML documentation install directory")
+
 option (LLVM_BUILD_EXTERNAL_COMPILER_RT
   "Build compiler-rt as an external project." OFF)
 
 # You can configure which libraries from LLVM you want to include in the
 # shared library by setting LLVM_DYLIB_COMPONENTS to a semi-colon delimited
 # list of LLVM components. All component names handled by llvm-config are valid.
 if(NOT DEFINED LLVM_DYLIB_COMPONENTS)
   set(LLVM_DYLIB_COMPONENTS "all" CACHE STRING

docs/CMake.rst

**LLVM_DOXYGEN_QHELPGENERATOR_PATH**:STRING
   ``find_program()`` can find. This option is only useful in combination with
   ``-DLLVM_ENABLE_DOXYGEN_QT_HELP=ON``; otherwise it has no
   effect.
 
 **LLVM_DOXYGEN_SVG**:BOOL
   Uses .svg files instead of .png files for graphs in the Doxygen output.
   Defaults to OFF.
 
+**LLVM_INSTALL_DOXYGEN_HTML_DIR**:STRING
+  The path to install Doxygen-generated HTML documentation to. This path can
+  either be absolute or relative to the CMAKE_INSTALL_PREFIX. Defaults to
+  `share/doc/llvm/doxygen-html`.
+
 **LLVM_ENABLE_SPHINX**:BOOL
   If specified, CMake will search for the ``sphinx-build`` executable and will make
   the ``SPHINX_OUTPUT_HTML`` and ``SPHINX_OUTPUT_MAN`` CMake options available.
   Defaults to OFF.
 
 **SPHINX_EXECUTABLE**:STRING
   The path to the ``sphinx-build`` executable detected by CMake.
 
**SPHINX_WARNINGS_AS_ERRORS**:BOOL
   If enabled then sphinx documentation warnings will be treated as
   errors. Defaults to ON.
 
 **LLVM_INSTALL_SPHINX_HTML_DIR**:STRING
   The path to install Sphinx-generated HTML documentation to. This path can
   either be absolute or relative to the CMAKE_INSTALL_PREFIX. Defaults to
   `share/doc/llvm/html`.
 
+**LLVM_INSTALL_OCAMLDOC_HTML_DIR**:STRING
+  The path to install OCamldoc-generated HTML documentation to. This path can
+  either be absolute or relative to the CMAKE_INSTALL_PREFIX. Defaults to
+  `share/doc/llvm/ocaml-html`.
+
 **LLVM_CREATE_XCODE_TOOLCHAIN**:BOOL
   OS X Only: If enabled CMake will generate a target named
   'install-xcode-toolchain'. This target will create a directory at
   $CMAKE_INSTALL_PREFIX/Toolchains containing an xctoolchain directory which can
   be used to override the default system tools. 
 
 **LLVM_BUILD_LLVM_DYLIB**:BOOL
   If enabled, the target for building the libLLVM shared library is added.

docs/CMakeLists.txt

add_custom_target(doxygen-llvm
     WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
     COMMENT "Generating llvm doxygen documentation." VERBATIM)
 
   if (LLVM_BUILD_DOCS)
     add_dependencies(doxygen doxygen-llvm)
   endif()
 
   if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
-    install(DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/doxygen/html
-      DESTINATION docs/html)
+    # ./ suffix is needed to copy the contents of html directory without
+    # appending html/ into LLVM_INSTALL_DOXYGEN_HTML_DIR.
+    install(DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/doxygen/html/.
+      DESTINATION "${LLVM_INSTALL_DOXYGEN_HTML_DIR}")
   endif()
 endif()
 endif()
 
 if (LLVM_ENABLE_SPHINX)
   if (SPHINX_FOUND)
     include(AddSphinxTarget)
     if (${SPHINX_OUTPUT_HTML})
add_custom_target(ocaml_doc
     COMMAND ${OCAMLFIND} ocamldoc -d ${CMAKE_CURRENT_BINARY_DIR}/ocamldoc/html
                                   -sort -colorize-code -html ${odoc_files}
     COMMAND ${CMAKE_COMMAND} -E copy ${CMAKE_CURRENT_SOURCE_DIR}/_ocamldoc/style.css
                                      ${CMAKE_CURRENT_BINARY_DIR}/ocamldoc/html)
 
   add_dependencies(ocaml_doc ${doc_targets})
 
   if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
-    install(DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/ocamldoc/html
-      DESTINATION docs/ocaml/html)
+    # ./ suffix is needed to copy the contents of html directory without
+    # appending html/ into LLVM_INSTALL_OCAMLDOC_HTML_DIR.
+    install(DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/ocamldoc/html/.
+      DESTINATION "${LLVM_INSTALL_OCAMLDOC_HTML_DIR}")
   endif()
 endif()