[Lldb-commits] [lldb] [lldb][CMake] Enforce lldbUtility and lldbHost layering invariants (PR #198952)

[Charles Zablit via lldb-commits]

================
@@ -60,6 +60,66 @@ function(_lldb_propagate_links_liblldb name libs)
   set_target_properties(${name} PROPERTIES LLDB_LINKS_LIBLLDB ${_links_liblldb})
 endfunction()
 
+# Configure-time scan: every #include "lldb/<Module>/..." in <SOURCES> and in
+# PUBLIC_HEADER_DIR (recursive) must reference OWN_MODULE or a name in
+# ALLOWED_MODULES, otherwise FATAL_ERROR. Catches accidental cross-module
+# includes that succeed at link time (e.g. on macOS) without a corresponding
+# CMake LINK_LIBS dependency.
+function(lldb_check_header_layering target)
+  cmake_parse_arguments(HC "" "PUBLIC_HEADER_DIR;OWN_MODULE"
+                          "SOURCES;ALLOWED_MODULES" ${ARGN})
+
+  set(_files)
+  foreach(src ${HC_SOURCES})
+    if(NOT IS_ABSOLUTE "${src}")
+      set(src "${CMAKE_CURRENT_SOURCE_DIR}/${src}")
+    endif()
+    # PARAM_UNPARSED_ARGUMENTS in add_lldb_library carries source files
+    # alongside llvm_add_library keywords like ADDITIONAL_HEADER_DIRS or
+    # LINK_COMPONENTS. Skip anything that isn't an existing file.
+    if(EXISTS "${src}" AND NOT IS_DIRECTORY "${src}")
+      list(APPEND _files "${src}")
+    endif()
+  endforeach()
+
+  if(HC_PUBLIC_HEADER_DIR AND EXISTS "${HC_PUBLIC_HEADER_DIR}")
+    file(GLOB_RECURSE _public_hdrs
+         "${HC_PUBLIC_HEADER_DIR}/*.h" "${HC_PUBLIC_HEADER_DIR}/*.hpp")
+    list(APPEND _files ${_public_hdrs})
+  endif()
+
+  set(_allowed ${HC_ALLOWED_MODULES} ${HC_OWN_MODULE})
+
+  foreach(file ${_files})
+    file(STRINGS "${file}" _includes
+         REGEX "^[ \t]*#[ \t]*include[ \t]+\"lldb/[A-Za-z_][A-Za-z0-9_]*/")
+    foreach(line ${_includes})
+      # Special case: lldb/Host/windows/windows.h is a system-header wrapper
+      # (sets NTDDI_VERSION/NOMINMAX/etc. before <windows.h> and undefs
+      # conflicting macros). It carries no module dependency but is the
+      # canonical way to pull in <windows.h> across the tree, so allow it
+      # from any target regardless of layering rules.
----------------
charles-zablit wrote:

```suggestion
      # Allow Windows system-header wrapper.
```

https://github.com/llvm/llvm-project/pull/198952