[clang-format] Add cmake target clang-format-style-options

This new custom target is for running dump_format_style.py to update
ClangFormatStyleOptions.rst if any of its dependencies changes.

Author: owenca

clang/lib/Format/CMakeLists.txt

@@ -53,3 +53,19 @@ foreach (file IN LISTS files)
 endforeach ()
 
 add_custom_target(clang-format-check-format DEPENDS ${check_format_depends})
+
+if(CLANG_INCLUDE_DOCS)
+  set(style_options_depends ${CMAKE_CURRENT_BINARY_DIR}/dummy_output)
+  set(docs_tools_dir ${CLANG_SOURCE_DIR}/docs/tools)
+  add_custom_command(OUTPUT ${style_options_depends}
+    COMMAND ${Python3_EXECUTABLE} dump_format_style.py &&
+            touch ${style_options_depends}
+    WORKING_DIRECTORY ${docs_tools_dir}
+    DEPENDS ${CLANG_SOURCE_DIR}/include/clang/Format/Format.h
+            ${CLANG_SOURCE_DIR}/include/clang/Tooling/Inclusions/IncludeStyle.h
+            ${CLANG_SOURCE_DIR}/docs/ClangFormatStyleOptions.rst
+            ${docs_tools_dir}/plurals.txt
+            ${docs_tools_dir}/dump_format_style.py
+    )
+  add_custom_target(clang-format-style-options DEPENDS ${style_options_depends})
+endif()