[clang] NFC: Make clang resource headers an interface library (PR #88317)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-x86

Author: Evan Wilde (etcwilde)

<details>
<summary>Changes</summary>

Making the clang resource headers into an interface library instead of a custom target means that we can attach the header search paths to the library. Targets that "link" against this library will automatically have the appropriate paths added to their header search paths to find them. Then downstream projects that embed a copy of clang can query the generated `ClangTargets.cmake` file for the header location instead of attempting to compute them.

---
Full diff: https://github.com/llvm/llvm-project/pull/88317.diff


1 Files Affected:

- (modified) clang/lib/Headers/CMakeLists.txt (+6-2) 


``````````diff
diff --git a/clang/lib/Headers/CMakeLists.txt b/clang/lib/Headers/CMakeLists.txt
index 97104ccd8db59c..0367f611526f41 100644
--- a/clang/lib/Headers/CMakeLists.txt
+++ b/clang/lib/Headers/CMakeLists.txt
@@ -437,14 +437,14 @@ foreach( f ${generated_files} )
 endforeach( f )
 
 function(add_header_target target_name file_list)
-  add_custom_target(${target_name} DEPENDS ${file_list})
+  add_library(${target_name} INTERFACE ${file_list})
   set_target_properties(${target_name} PROPERTIES
     FOLDER "Misc"
     RUNTIME_OUTPUT_DIRECTORY "${output_dir}")
 endfunction()
 
 # The catch-all clang-resource-headers target
-add_custom_target("clang-resource-headers" ALL DEPENDS ${out_files})
+add_library(clang-resource-headers INTERFACE ${out_files})
 set_target_properties("clang-resource-headers" PROPERTIES
   FOLDER "Misc"
   RUNTIME_OUTPUT_DIRECTORY "${output_dir}")
@@ -501,6 +501,10 @@ add_header_target("windows-resource-headers" ${windows_only_files})
 add_header_target("utility-resource-headers" ${utility_files})
 
 get_clang_resource_dir(header_install_dir SUBDIR include)
+target_include_directories(clang-resource-headers INTERFACE
+  $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
+  $<INSTALL_INTERFACE:${header_install_dir}>)
+set_property(GLOBAL APPEND PROPERTY CLANG_EXPORTS clang-resource-headers)
 
 #############################################################
 # Install rules for the catch-all clang-resource-headers target

``````````

</details>


https://github.com/llvm/llvm-project/pull/88317