cmake: Link lldb libraries and tools with libclang-cpp.so when CLANG_LINK_LLVM_DYLIB=ON

[mgorny]

Would it be bad if I said I like mine more? I'm not a fan of implicit logic, and relying on specific filenames.

[tstellar]

In D68071#1695396, @mgorny wrote:

Would it be bad if I said I like mine more? I'm not a fan of implicit logic, and relying on specific filenames.

No, that's fine. I actually started to implement it the same way as your patch, but I was worried I would miss some cases, so I went with this approach. We can drop this one.

[mgorny]

Not saying this will happen here but in clang-tools-extra, I had to deal with some clang* libraries being part of libclang-cpp, and some (those added by cte) being not.

lldb/cmake/modules/AddLLDB.cmake

function(lldb_tablegen)
 
   if(LTG_TARGET)
     add_public_tablegen_target(${LTG_TARGET})
     set_target_properties( ${LTG_TARGET} PROPERTIES FOLDER "LLDB tablegenning")
     set_property(GLOBAL APPEND PROPERTY LLDB_TABLEGEN_TARGETS ${LTG_TARGET})
   endif()
 endfunction(lldb_tablegen)
 
+# Filter out clang libraries and add clang_shared when CLANG_LINK_CLANG_DYLIB=ON
+function(lldb_filter_link_libs link_libs)
+
+  set(link_libs_list ${${link_libs}})
+  list(LENGTH link_libs_list lib_count)
+  if (CLANG_LINK_CLANG_DYLIB AND lib_count GREATER 0)
+      list(FILTER link_libs_list EXCLUDE REGEX "^clang")
+      list(LENGTH link_libs_list filtered_lib_count)
+      if (filtered_lib_count LESS lib_count)
+        list(APPEND link_libs_list clang-cpp)
+      endif()
+  endif()
+  set(${link_libs} ${link_libs_list} PARENT_SCOPE)
+
+endfunction(lldb_filter_link_libs)
+
 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
else()
     if(PARAM_ENTITLEMENTS)
       set(pass_ENTITLEMENTS ENTITLEMENTS ${PARAM_ENTITLEMENTS})
     endif()
 
     if(LLDB_NO_INSTALL_DEFAULT_RPATH)
       set(pass_NO_INSTALL_RPATH NO_INSTALL_RPATH)
     endif()
 
+    lldb_filter_link_libs(PARAM_LINK_LIBS)
+
     llvm_add_library(${name} ${libkind} ${srcs}
       LINK_LIBS ${PARAM_LINK_LIBS}
       DEPENDS ${PARAM_DEPENDS}
       ${pass_ENTITLEMENTS}
       ${pass_NO_INSTALL_RPATH}
     )
   endif()
 
function(add_lldb_executable name)
 
   list(APPEND LLVM_LINK_COMPONENTS ${ARG_LINK_COMPONENTS})
   add_llvm_executable(${name}
     ${pass_ENTITLEMENTS}
     ${pass_NO_INSTALL_RPATH}
     ${ARG_UNPARSED_ARGUMENTS}
   )
 
+  lldb_filter_link_libs(ARG_LINK_LIBS)
+
   target_link_libraries(${name} PRIVATE ${ARG_LINK_LIBS})
   set_target_properties(${name} PROPERTIES FOLDER "lldb executables")
 
   if(ARG_GENERATE_INSTALL)
     set(install_dest bin)
     if(ARG_INSTALL_PREFIX)
       set(install_dest ${ARG_INSTALL_PREFIX})
     endif()