[clang-format][CMake] Generate formatting options docs during build

This patch changes up the CMake configuration so that
ClangFormatStyleOptions.rst has the format style options section
generated by the dump_format_style.py python script during the build
rather than manually. This allows us to remove ~6000 lines of
automatically generated documentation from the repository.

If the context of the options is needed while generating the docs, it is
easy enough to open up the generated file with the options from within
the build directory after the clang-format-style-options target has been
built.

Author: boomanaiden154

clang/docs/CMakeLists.txt

@@ -143,8 +143,17 @@ if (LLVM_ENABLE_SPHINX)
     gen_rst_file_from_td(DiagnosticsReference.rst -gen-diag-docs ../include/clang/Basic/Diagnostic.td "${docs_targets}")
     gen_rst_file_from_td(ClangCommandLineReference.rst -gen-opt-docs ../include/clang/Driver/ClangOptionDocs.td "${docs_targets}")
 
+    add_custom_target(clang-format-style-options
+      COMMAND "${Python3_EXECUTABLE}" "${CLANG_SOURCE_DIR}/docs/tools/dump_format_style.py"
+      WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}"
+      DEPENDS "${CLANG_SOURCE_DIR}/include/clang/Format/Format.h"
+              "${CLANG_SOURCE_DIR}/include/clang/Tooling/Inclusions/IncludeStyle.h"
+              "${CLANG_SOURCE_DIR}/docs/tools/dump_format_style.py"
+              copy-clang-rst-docs
+    )
+
     foreach(target ${docs_targets})
-      add_dependencies(${target} copy-clang-rst-docs)
+      add_dependencies(${target} copy-clang-rst-docs clang-format-style-options)
     endforeach()
   endif()
 endif()