[libc] rename newhdrgen to just hdrgen (#118545)

Link: #117208
Fixes: #117254

Author: nickdesaulniers

libc/CMakeLists.txt

@@ -57,7 +57,7 @@ if(LIBC_BUILD_GPU_LOADER OR ((NOT LLVM_RUNTIMES_BUILD) AND LLVM_LIBC_GPU_BUILD))
   return()
 endif()
 
-add_subdirectory(newhdrgen)
+add_subdirectory(hdrgen)
 
 option(LIBC_CMAKE_VERBOSE_LOGGING
   "Log details warnings and notifications during CMake configuration." OFF)

libc/cmake/modules/LLVMLibCHeaderRules.cmake

@@ -112,7 +112,7 @@ function(add_gen_header target_name)
 
   add_custom_command(
     OUTPUT ${out_file}
-    COMMAND ${Python3_EXECUTABLE} ${LIBC_SOURCE_DIR}/newhdrgen/yaml_to_classes.py
+    COMMAND ${Python3_EXECUTABLE} ${LIBC_SOURCE_DIR}/hdrgen/yaml_to_classes.py
             ${yaml_file}
             --h_def_file ${def_file}
             ${entry_points}
@@ -126,7 +126,7 @@ function(add_gen_header target_name)
     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
+      COMMAND ${Python3_EXECUTABLE} ${LIBC_SOURCE_DIR}/hdrgen/yaml_to_classes.py
               ${yaml_file}
               --export-decls
               ${entry_points}

libc/docs/dev/header_generation.rst

@@ -0,0 +1,17 @@
+if(LLVM_LIBC_FULL_BUILD)
+  enable_testing()
+
+  set(NEWHDGEN_TESTS_DIR ${CMAKE_CURRENT_SOURCE_DIR}/tests)
+  set(TEST_OUTPUT_DIR ${CMAKE_BINARY_DIR}/hdrgen/output)
+
+  add_test(
+    NAME hdrgen_integration_test
+    COMMAND python3 ${NEWHDGEN_TESTS_DIR}/test_integration.py --output_dir ${TEST_OUTPUT_DIR}
+  )
+
+  add_custom_target(check-hdrgen
+    COMMAND ${CMAKE_CTEST_COMMAND} -R hdrgen_integration_test --output-on-failure
+  )
+
+  message(STATUS "Integration test for hdrgen added.")
+endif()