This is the first step of a migration to split apart upb_proto_library() into upb_c_proto_library() and upb_minitable_proto_library().
PiperOrigin-RevId: 563837216
I merged a handful of PRs on the upb repo after upb moved into the protobuf repo. This PR cherry-picks them here so that they will not be lost.
```
commit 7afb426a5a
Author: Keith Smiley <keithbsmiley@gmail.com>
Date: Thu Sep 7 11:36:01 2023 -0700
[bazel] Fix disallowing dylibs on darwin (#1180)
Since this bazel commit
ec5553352f
building dylibs like the ones in this rule on darwin platforms has been
unsupported. This feature is a default C++ toolchain feature to indicate
this. In bazel 7.x these dylibs will fail to link if they are still
built. As far as I can tell in the tests even if they are built they are
never used on macOS.
Co-authored-by: Adam Cozzette <acozzette@google.com>
commit 72decab5ec
Author: Keith Smiley <keithbsmiley@gmail.com>
Date: Thu Sep 7 09:42:20 2023 -0700
Add missing darwin_x86_64 CPU (#1181)
This CPU is often used when cross compiling from M1 machines. I'm also
hoping we can remove the legacy 'darwin' CPU.
commit ccadaf3196
Author: messense <messense@icloud.com>
Date: Fri Sep 8 00:28:54 2023 +0800
Fix `PyUpb_Message_MergeInternal` segfault (#1338)
when `PyUpb_Message_MergeFromString` returns `NULL`, currently
`PyUpb_Message_MergeInternal` will call `Py_DECREF` on `NULL`
which results in a segmentation fault.
This patch switches to `Py_XDECREF` to fix the segfault.
commit 2a5724d86e
Author: Kevin Greene <kgreenek@gmail.com>
Date: Wed Sep 6 16:46:35 2023 -0700
Fix lambda capture compiler error with c++20 (#1502)
When compiling with C++20, the following error is produced:
```
upb/mini_table.hpp:63:22: note: add explicit 'this' or '*this' capture
upb/mini_table.hpp: In lambda function:
upb/mini_table.hpp:71:22: error: implicit capture of 'this' via '[=]' is deprecated in C++20 [-Werror=deprecated]
71 | return appender_([=](char* buf) {
```
In C++20, it is no longer allowed to implicitly capture 'this' in a
lambda using [=].
This commit explicitly captures required values in the appropriate
lambdas and removes all uses of [=] with lambdas.
```
Closes#13908
COPYBARA_INTEGRATE_REVIEW=https://github.com/protocolbuffers/protobuf/pull/13908 from acozzette:upb 7afb426a5a
PiperOrigin-RevId: 563784513
Currently the generated code contains 2 loads of ptr_ b/c it's an atomic:
one in HasSize and one in AllocateFromExisting.
Combine these to be a single load.
name old cpu/op new cpu/op delta
BM_ArenaAlloc/100 250ns ± 2% 229ns ± 1% -8.20% (p=0.000 n=54+47)
BM_ArenaAllocWithCleanup/100 865ns ± 1% 812ns ± 2% -6.15% (p=0.000 n=57+56)
PiperOrigin-RevId: 563698727