[lldb][CMake] Enforce not letting lldbUtility link against any other lldb libs

[bulbazord]

Summary

lldbUtility is not supposed to depend on anything else in lldb. Let's
enforce that constraint in CMake rather than hoping something doesn't
slip in under the radar.

[bulbazord]

Note that this won't stop people from performing #include with non-Utility files, but this marks the intent that Utility is not supposed to be using anything else in lldb.

[JDevlieghere]

LGTM

[JDevlieghere]

Can we do something similar for plugins?

[bulbazord]

Can we do something similar for plugins?

Yep, I'll tackle that in a follow-up.

[bulbazord]

In D146473#4210440, @bulbazord wrote:

Can we do something similar for plugins?

Yep, I'll tackle that in a follow-up.

For those following along at home: D146553

lldb/cmake/modules/AddLLDB.cmake

 function(add_lldb_library name)
   include_directories(BEFORE
     ${CMAKE_CURRENT_BINARY_DIR}
 )
 
   # only supported parameters to this macro are the optional
   # MODULE;SHARED;STATIC library type and source files
   cmake_parse_arguments(PARAM
-    "MODULE;SHARED;STATIC;OBJECT;PLUGIN;FRAMEWORK"
+    "MODULE;SHARED;STATIC;OBJECT;PLUGIN;FRAMEWORK;NO_INTERNAL_DEPENDENCIES"
     "INSTALL_PREFIX;ENTITLEMENTS"
     "EXTRA_CXXFLAGS;DEPENDS;LINK_LIBS;LINK_COMPONENTS;CLANG_LIBS"
     ${ARGN})
   llvm_process_sources(srcs ${PARAM_UNPARSED_ARGUMENTS})
   list(APPEND LLVM_LINK_COMPONENTS ${PARAM_LINK_COMPONENTS})
 
+  if(PARAM_NO_INTERNAL_DEPENDENCIES)
+    foreach(link_lib ${PARAM_LINK_LIBS})
+      if (link_lib MATCHES "^lldb")
+        message(FATAL_ERROR
+          "Library ${name} cannot depend on any other lldb libs "
+          "(Found ${link_lib} in LINK_LIBS)")
+      endif()
+    endforeach()
+  endif()
+
   if(PARAM_PLUGIN)
     set_property(GLOBAL APPEND PROPERTY LLDB_PLUGINS ${name})
   endif()
 
   if (MSVC_IDE OR XCODE)
     string(REGEX MATCHALL "/[^/]+" split_path ${CMAKE_CURRENT_SOURCE_DIR})
     list(GET split_path -1 dir)
     file(GLOB_RECURSE headers

lldb/source/Utility/CMakeLists.txt

 if (CMAKE_SYSTEM_NAME MATCHES "Windows")
   list(APPEND LLDB_SYSTEM_LIBS ws2_32 rpcrt4)
 endif ()
 
 if (NOT HAVE_CXX_ATOMICS64_WITHOUT_LIB )
     list(APPEND LLDB_SYSTEM_LIBS atomic)
 endif()
 
-add_lldb_library(lldbUtility
+add_lldb_library(lldbUtility NO_INTERNAL_DEPENDENCIES
   ArchSpec.cpp
   Args.cpp
   Baton.cpp
   Broadcaster.cpp
   CompletionRequest.cpp
   Connection.cpp
   ConstString.cpp
   DataBufferHeap.cpp