Revert "[libc] newheadergen: configured cmake" (#99414)

Summary: Reverts #98828

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Differential Revision: https://phabricator.intern.facebook.com/D60251771

Author: aaryanshukla

libc/CMakeLists.txt

@@ -72,7 +72,6 @@ option(LIBC_BUILD_GPU_LOADER "Always build the GPU loader utilities" OFF)
 if(LIBC_BUILD_GPU_LOADER OR (LLVM_LIBC_GPU_BUILD AND NOT LLVM_RUNTIMES_BUILD))
   add_subdirectory(utils/gpu)
 endif()
-option(LIBC_USE_NEW_HEADER_GEN "Generate header files using new headergen instead of the old one" OFF)
 
 set(NEED_LIBC_HDRGEN FALSE)
 if(NOT LLVM_RUNTIMES_BUILD)

libc/cmake/modules/LLVMLibCHeaderRules.cmake

@@ -66,106 +66,7 @@ function(add_header target_name)
   )
 endfunction(add_header)
 
-function(add_gen_header2 target_name)
-  cmake_parse_arguments(
-    "ADD_GEN_HDR2"
-    "PUBLIC" # No optional arguments
-    "YAML_FILE;DEF_FILE;GEN_HDR" # Single value arguments
-    "DEPENDS"     # Multi value arguments
-    ${ARGN}
-  )
-  get_fq_target_name(${target_name} fq_target_name)
-  if(NOT LLVM_LIBC_FULL_BUILD)
-    add_library(${fq_target_name} INTERFACE)
-    return()
-  endif()
-  if(NOT ADD_GEN_HDR2_DEF_FILE)
-    message(FATAL_ERROR "`add_gen_hdr2` rule requires DEF_FILE to be specified.")
-  endif()
-  if(NOT ADD_GEN_HDR2_GEN_HDR)
-    message(FATAL_ERROR "`add_gen_hdr2` rule requires GEN_HDR to be specified.")
-  endif()
-  if(NOT ADD_GEN_HDR2_YAML_FILE)
-    message(FATAL_ERROR "`add_gen_hdr2` rule requires YAML_FILE to be specified.")
-  endif()
-
-  set(absolute_path ${CMAKE_CURRENT_SOURCE_DIR}/${ADD_GEN_HDR2_GEN_HDR})
-  file(RELATIVE_PATH relative_path ${LIBC_INCLUDE_SOURCE_DIR} ${absolute_path})
-  set(out_file ${LIBC_INCLUDE_DIR}/${relative_path})
-  set(yaml_file ${CMAKE_SOURCE_DIR}/${ADD_GEN_HDR2_YAML_FILE})
-  set(def_file ${CMAKE_CURRENT_SOURCE_DIR}/${ADD_GEN_HDR2_DEF_FILE})
-
-  set(fq_data_files "")
-  if(ADD_GEN_HDR2_DATA_FILES)
-    foreach(data_file IN LISTS ADD_GEN_HDR2_DATA_FILES)
-      list(APPEND fq_data_files "${CMAKE_CURRENT_SOURCE_DIR}/${data_file}")
-    endforeach(data_file)
-  endif()
-
-  set(entry_points "${TARGET_ENTRYPOINT_NAME_LIST}")
-  list(TRANSFORM entry_points PREPEND "--e=")
-
-  add_custom_command(
-    OUTPUT ${out_file}
-    COMMAND ${Python3_EXECUTABLE} ${LIBC_SOURCE_DIR}/newhdrgen/yaml_to_classes.py
-            ${yaml_file}
-            --h_def_file ${def_file}
-            ${entry_points}
-            --output_dir ${out_file}
-    DEPENDS ${yaml_file} ${def_file} ${fq_data_files}
-    COMMENT "Generating header ${ADD_GEN_HDR2_GE2N_HDR} from ${yaml_file} and ${def_file}"
-  )
-  if(LIBC_TARGET_OS_IS_GPU)
-    file(MAKE_DIRECTORY ${LIBC_INCLUDE_DIR}/llvm-libc-decls)
-    file(MAKE_DIRECTORY ${LIBC_INCLUDE_DIR}/llvm-libc-decls/gpu)
-    set(decl_out_file ${LIBC_INCLUDE_DIR}/llvm-libc-decls/${relative_path})
-    add_custom_command(
-      OUTPUT ${decl_out_file}
-      COMMAND ${Python3_EXECUTABLE} ${LIBC_SOURCE_DIR}/newhdrgen/yaml_to_classes.py
-              ${yaml_file}
-              --export-decls
-              ${entry_points}
-              --output_dir ${decl_out_file}
-      WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
-      DEPENDS ${yaml_file} ${fq_data_files}
-    )
-  endif()
-  
-  if(ADD_GEN_HDR2_DEPENDS)
-    get_fq_deps_list(fq_deps_list ${ADD_GEN_HDR2_DEPENDS})
-    # Dependencies of a add_header target can only be another add_gen_header target
-    # or an add_header target.
-    foreach(dep IN LISTS fq_deps_list)
-      get_target_property(header_file ${dep} HEADER_FILE_PATH)
-      if(NOT header_file)
-        message(FATAL_ERROR "Invalid dependency '${dep}' for '${fq_target_name}'.")
-      endif()
-    endforeach()
-  endif()
-  set(generated_hdr_target ${fq_target_name}.__generated_hdr__)
-  add_custom_target(
-    ${generated_hdr_target}
-    DEPENDS ${out_file} ${fq_deps_list} ${decl_out_file}
-  )
-
-  add_header_library(
-    ${target_name}
-    HDRS
-      ${out_file}
-  )
-
-  add_dependencies(${fq_target_name} ${generated_hdr_target})
-
-  set_target_properties(
-    ${fq_target_name}
-    PROPERTIES
-      HEADER_FILE_PATH ${out_file}
-      DEPS "${fq_deps_list}"
-  )
-
-
-endfunction(add_gen_header2)
-
+# A rule for generated header file targets.
 # Usage:
 #     add_gen_header(
 #       <target name>