🥴 Add some YOLO patches to make modules work better

Author: neqochan

ll/args.bzl

@@ -307,12 +307,18 @@ def compile_object_args(
     # Always use experimental libcxx features.
     args.add("-D_LIBCPP_ENABLE_EXPERIMENTAL")
 
+    # TODO: Module precompilations embed absolute paths in precompiled binaries.
+    # We use this workaround to prevent abi_tag attribute redeclaration errors
+    # in libcxx/include/__bit_reference. We need to figure out how we can
+    # re-enable abi-tagging.
+    args.add("-D_LIBCPP_NO_ABI_TAG")
+
     # Additional compile flags.
     args.add_all(ctx.attr.compile_flags)
 
     # To keep precompilations sandboxed, embed used headers in the pcm.
     # TODO: This does not work yet. For some reason we are still required to
-    #       disable sandboxint in precompilations.
+    #       disable sandboxing in precompilations.
     if out_file.extension == "pcm":
         args.add("-Xclang")
         args.add("-fmodules-embed-all-files")

ll/extensions.bzl

@@ -92,6 +92,7 @@ def _llvm_configure_extension_impl(ctx):
             ),
         ],
         patches = [
+            "@rules_ll//patches:back_inserter_patch.diff",
             "@rules_ll//patches:disable_synth_three_way_patch.diff",
             "@rules_ll//patches:compiler-rt_float128_patch.diff",
             "@rules_ll//patches:mallinfo2_patch.diff",

patches/back_inserter_patch.diff

@@ -0,0 +1,14 @@
+diff --git a/libcxx/include/__iterator/back_insert_iterator.h b/libcxx/include/__iterator/back_insert_iterator.h
+index da58b860e3..9aec7aa7cf 100644
+--- a/libcxx/include/__iterator/back_insert_iterator.h
++++ b/libcxx/include/__iterator/back_insert_iterator.h
+@@ -67,6 +67,9 @@ back_inserter(_Container& __x)
+     return back_insert_iterator<_Container>(__x);
+ }
+ 
++template <class _Container> _LIBCPP_HIDE_FROM_ABI
++back_insert_iterator(_Container& __x) -> back_insert_iterator<_Container>;
++
+ _LIBCPP_END_NAMESPACE_STD
+ 
+ #endif // _LIBCPP___ITERATOR_BACK_INSERT_ITERATOR_H