Hey Nathan, Capabilities were introduced (IIRC) in Clang 3.5 or so. The version you have (3.4.2) is, I think, too old.
There was a support document recently published which outlines some of what you can expect for building Google libraries: https://opensource.google/documentation/policies/cplusplus-support#support_criteria_2 That doc points to devtoolset-7 as the special requirement for older versions of RHEL. I would agree with its advice to use Clang/LLVM 6 or newer... there are some non-trivial C++ Language Defect Reports (i.e., bugs in the C++ standard) that were addressed in the [3.4, 6.0) range, but those fixes don't generally get ported back. With the Protobuf 3.15 series, you might get by with Clang 3.6 or newer, but especially going forward, you might want to consider Clang 6 (or newer) as a hard requirement. In your case, you mention specifically wanting consistency. Since your Mac is (presumably) using Apple Clang from Xcode, it probably corresponds to Clang/LLVM version 12 or 13. There are some pretty significant changes since Clang 6, especially around diagnostics, so the closer you can get, the better. Note also that macOS uses (LLVM's) libc++, while CentOS will generally use (GCC's) libstdc++... those have very different implementations, and slightly different behavior near the edges of the C++ standard. It looks like RHEL has LLVM toolchain packages up to version 13, although I can't find corresponding CentOS packages. You might have some luck with the RHEL releases from https://releases.llvm.org/download.html . Hope that helps... --dlj On Wed, Jun 29, 2022 at 2:14 PM Nathan Cooprider <[email protected]> wrote: > I can build the protocol buffers ( > https://github.com/protocolbuffers/protobuf/tree/v3.15.8) using gcc on > CentOS 7 or using clang on my Mac, but not using clang on CentOS 7. I feel > like I'm missing something obvious. > > $ unzip protobuf-3.15.8.zip > $ cd protobuf-3.15.8 > > # on my Mac (host machine) > $ mkdir build_on_mac > $ cd build_on_mac > $ cmake ../cmake -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ > -Dprotobuf_BUILD_TESTS=OFF > $ make > $ cd .. > > # on my CentOS 7 box (currently a VM, but have an actual box too) > $ mkdir build_on_linux > $ cd build_on_linux > $ cmake ../cmake -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ > -Dprotobuf_BUILD_TESTS=OFF > $ make > > That second one gets me this: > . . . > [ 31%] Building CXX object > CMakeFiles/libprotobuf.dir/vagrant/protobuf-3.15.8/src/google/protobuf/any.cc.o > In file included from > /vagrant/protobuf-3.15.8/src/google/protobuf/any.cc:34: > In file included from > /vagrant/protobuf-3.15.8/src/google/protobuf/descriptor.h:65: > /vagrant/protobuf-3.15.8/src/google/protobuf/stubs/mutex.h:117:7: warning: > unknown attribute 'capability' ignored [-Wattributes] > class GOOGLE_PROTOBUF_CAPABILITY("mutex") PROTOBUF_EXPORT WrappedMutex { > ^ > /vagrant/protobuf-3.15.8/src/google/protobuf/stubs/mutex.h:55:54: note: > expanded from macro 'GOOGLE_PROTOBUF_CAPABILITY' > #define GOOGLE_PROTOBUF_CAPABILITY(x) __attribute__((capability(x))) > ^ > /vagrant/protobuf-3.15.8/src/google/protobuf/stubs/mutex.h:120:15: warning: > unknown attribute 'acquire_capability' ignored [-Wattributes] > void Lock() GOOGLE_PROTOBUF_ACQUIRE() { mu_.lock(); } > ^ > /vagrant/protobuf-3.15.8/src/google/protobuf/stubs/mutex.h:52:18: note: > expanded from macro 'GOOGLE_PROTOBUF_ACQUIRE' > __attribute__((acquire_capability(__VA_ARGS__))) > ^ > /vagrant/protobuf-3.15.8/src/google/protobuf/stubs/mutex.h:121:17: warning: > unknown attribute 'release_capability' ignored [-Wattributes] > void Unlock() GOOGLE_PROTOBUF_RELEASE() { mu_.unlock(); } > ^ > /vagrant/protobuf-3.15.8/src/google/protobuf/stubs/mutex.h:54:18: note: > expanded from macro 'GOOGLE_PROTOBUF_RELEASE' > __attribute__((release_capability(__VA_ARGS__))) > ^ > In file included from > /vagrant/protobuf-3.15.8/src/google/protobuf/any.cc:36: > /vagrant/protobuf-3.15.8/src/google/protobuf/message.h:234:13: error: > constexpr > constructor never produces a constant expression > [-Winvalid-constexpr] > constexpr Message() {} > ^ > /vagrant/protobuf-3.15.8/src/google/protobuf/message.h:234:13: note: > non-literal type 'google::protobuf::MessageLite' cannot be used in a > constant expression > 3 warnings and 1 error generated. > make[2]: *** > [CMakeFiles/libprotobuf.dir/vagrant/protobuf-3.15.8/src/google/protobuf/any.cc.o] > Error 1 > make[1]: *** [CMakeFiles/libprotobuf.dir/all] Error 2 > make: *** [all] Error 2 > > I'd like to use clang for cross compiling and toolchain consistency > reasons. That's the error I get both in my VM and on my actual machine. > > Additional info: > $ uname -a ; cmake --version ; clang --version > Linux localhost.localdomain 3.10.0-1160.15.2.el7.x86_64 #1 SMP Wed Feb 3 > 15:06:38 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux > cmake version 3.23.2 > > CMake suite maintained and supported by Kitware (kitware.com/cmake). > clang version 3.4.2 (tags/RELEASE_34/dot2-final) > Target: x86_64-redhat-linux-gnu > Thread model: posix > > Thanks for any help you can provide. > > Nathan > > -- > You received this message because you are subscribed to the Google Groups > "Protocol Buffers" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/protobuf/7ba0a048-be95-42f0-9af0-d89067d410a7n%40googlegroups.com > <https://groups.google.com/d/msgid/protobuf/7ba0a048-be95-42f0-9af0-d89067d410a7n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "Protocol Buffers" group. 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