[Bug]: Riscv build of Protobuf fails due to abseil

[apcameron]

Describe the issue

Refer to protocolbuffers/protobuf#14549

Steps to reproduce the problem

Refer protocolbuffers/protobuf#14549

What version of Abseil are you using?

Unknown

What operating system and version are you using?

Linux

What compiler and version are you using?

gcc 12

What build system are you using?

Refer to protocolbuffers/protobuf#14549

Additional context

No response

[derekmauro]

I have no way of testing RISC-V, but I think the problem is that the code needs to be linked with -latomic. Can you try adding -latomic to your linker options? I don't know what build system you are using since you didn't answer that question, but I would accept a pull request to add it if someone could figure how where it needs to be added and test the fix.

[apcameron]

I managed to get protobuf to compile clean with the following diff

diff --git a/CMakeLists.txt b/CMakeLists.txt
index f78fccc27..51e866bc1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -191,7 +191,8 @@ if (NOT MSVC)
       return static_cast<int>(std::atomic<int64_t>{});
     }
   " protobuf_HAVE_BUILTIN_ATOMICS)
-  if (NOT protobuf_HAVE_BUILTIN_ATOMICS)
+  if (NOT protobuf_HAVE_BUILTIN_ATOMICS OR ${CMAKE_SYSTEM_PROCESSOR} MATCHES
+         "riscv") 
     set(protobuf_LINK_LIBATOMIC true)
   endif (NOT protobuf_HAVE_BUILTIN_ATOMICS)
   set(CMAKE_REQUIRED_FLAGS ${OLD_CMAKE_REQUIRED_FLAGS})