[PATCH] D30517: [libc++abi] Add option to enable definitions for the new/delete overloads.

[Eric Fiselier via Phabricator via cfe-commits]

EricWF added a comment.

In https://reviews.llvm.org/D30517#690328, @mehdi_amini wrote:

> LGTM.






================
Comment at: CMakeLists.txt:416
+set(LIBCXXABI_HAS_UNDEFINED_SYMBOLS ((NOT LIBCXXABI_ENABLE_NEW_DELETE_DEFINITIONS)
+    OR (LIBCXXABI_BUILD_EXTERNAL_THREAD_LIBRARY AND LIBCXXABI_ENABLE_SHARED)))
+
----------------
mehdi_amini wrote:
> It is unrelated to this change, but I'm wondering about the `LIBCXXABI_BUILD_EXTERNAL_THREAD_LIBRARY` condition. I see undefined reference to libc symbols.
> That said we're linking to libSystem which provided everything, so I'm not even sure why `dynamic_lookup` is needed at all?
The external thread library configuration is not something you have to worry about.  The issue this configuration handles is that libc++abi.so in unable to link to libc++external_threads.a, and instead expects the user to manually link libc++external_threads.a or it expects libc++ to handle the linking and undefined symbols later.

Once again you're never going to run into this since you don't use an externalized threading library. 


https://reviews.llvm.org/D30517