This warning is appearing because of an interaction between CMake and a change in the linker on macOS. The old linker wouldn't rescan static libraries specified earlier in the command-line to resolve symbols needed by static libraries specified later in the command-line, so CMake inserted duplicates of static libraries to ensure all the dependencies were resolved. The new linker does rescan (so the duplicates aren't necessary) and complains about the duplication.
There's a discussion of this here: https://discourse.cmake.org/t/avoid-duplicate-linking-to-avoid-xcode-15-warnings/9084/9 Apparently setting cmake_minimum_required to version 3.29 or setting policy CMP0156 <https://cmake.org/cmake/help/latest/policy/CMP0156.html> to NEW will make CMake automatically deduplicate static libraries when using the new macOS linker as well as any other platforms where the linker rescans. On Saturday, 16 November 2024 at 18:16:59 UTC Tony Liao wrote: > Hello! > > In principle, we agree that our build should not be generating unnecessary > warnings, but it is relatively speaking lower on our priority list. We > generally try to reduce warnings where possible, incrementally, as we work > on the codebase. If you're interested in helping to reduce noisy warnings, > we'd welcome any PRs to that effect. > > Thanks! > Tony > > On Saturday, November 16, 2024 at 1:07:58 PM UTC-5 [email protected] wrote: > >> Hello Dev, >> >> I see the following warnings during the build protobuf v28.2 on macOS: >> >> [ 90%] Linking CXX executable protoc-gen-upb >> ld: warning: ignoring duplicate libraries: >> 'third_party/abseil-cpp/absl/base/libabsl_base.a', >> 'third_party/abseil-cpp/absl/base/libabsl_log_severity.a', >> 'third_party/abseil-cpp/absl/hash/libabsl_hash.a', >> 'third_party/abseil-cpp/absl/log/libabsl_log_globals.a', >> 'third_party/abseil-cpp/absl/random/libabsl_random_distributions.a', >> 'third_party/abseil-cpp/absl/status/libabsl_status.a', >> 'third_party/abseil-cpp/absl/strings/libabsl_cord.a', >> 'third_party/abseil-cpp/absl/strings/libabsl_strings.a', >> 'third_party/abseil-cpp/absl/synchronization/libabsl_synchronization.a', >> 'third_party/abseil-cpp/absl/time/libabsl_time.a' >> [ 90%] Built target protoc-gen-upb >> [ 91%] Building CXX object >> CMakeFiles/protoc-gen-upbdefs.dir/upb_generator/common.cc.o >> [ 91%] Building CXX object >> CMakeFiles/protoc-gen-upbdefs.dir/upb_generator/file_layout.cc.o >> [ 91%] Building CXX object >> CMakeFiles/protoc-gen-upbdefs.dir/upb_generator/mangle.cc.o >> [ 91%] Building CXX object >> CMakeFiles/protoc-gen-upbdefs.dir/upb_generator/protoc-gen-upbdefs.cc.o >> [ 91%] Building C object >> CMakeFiles/protoc-gen-upbdefs.dir/upb_generator/cmake/google/protobuf/compiler/plugin.upb_minitable.c.o >> [ 92%] Linking CXX executable protoc-gen-upbdefs >> ld: warning: ignoring duplicate libraries: >> 'third_party/abseil-cpp/absl/base/libabsl_base.a', >> 'third_party/abseil-cpp/absl/base/libabsl_log_severity.a', >> 'third_party/abseil-cpp/absl/hash/libabsl_hash.a', >> 'third_party/abseil-cpp/absl/log/libabsl_log_globals.a', >> 'third_party/abseil-cpp/absl/random/libabsl_random_distributions.a', >> 'third_party/abseil-cpp/absl/status/libabsl_status.a', >> 'third_party/abseil-cpp/absl/strings/libabsl_cord.a', >> 'third_party/abseil-cpp/absl/strings/libabsl_strings.a', >> 'third_party/abseil-cpp/absl/synchronization/libabsl_synchronization.a', >> 'third_party/abseil-cpp/absl/time/libabsl_time.a' >> [ 92%] Built target protoc-gen-upbdefs >> [ 92%] Building CXX object >> CMakeFiles/protoc-gen-upb_minitable.dir/upb_generator/common.cc.o >> [ 92%] Building CXX object >> CMakeFiles/protoc-gen-upb_minitable.dir/upb_generator/file_layout.cc.o >> [ 93%] Building CXX object >> CMakeFiles/protoc-gen-upb_minitable.dir/upb_generator/mangle.cc.o >> [ 93%] Building CXX object >> CMakeFiles/protoc-gen-upb_minitable.dir/upb_generator/names.cc.o >> [ 93%] Building CXX object >> CMakeFiles/protoc-gen-upb_minitable.dir/upb_generator/protoc-gen-upb_minitable-main.cc.o >> [ 93%] Building CXX object >> CMakeFiles/protoc-gen-upb_minitable.dir/upb_generator/protoc-gen-upb_minitable.cc.o >> [ 93%] Building C object >> CMakeFiles/protoc-gen-upb_minitable.dir/upb_generator/cmake/google/protobuf/compiler/plugin.upb_minitable.c.o >> [ 93%] Linking CXX executable protoc-gen-upb_minitable >> ld: warning: ignoring duplicate libraries: >> 'third_party/abseil-cpp/absl/base/libabsl_base.a', >> 'third_party/abseil-cpp/absl/base/libabsl_log_severity.a', >> 'third_party/abseil-cpp/absl/hash/libabsl_hash.a', >> 'third_party/abseil-cpp/absl/log/libabsl_log_globals.a', >> 'third_party/abseil-cpp/absl/random/libabsl_random_distributions.a', >> 'third_party/abseil-cpp/absl/status/libabsl_status.a', >> 'third_party/abseil-cpp/absl/strings/libabsl_cord.a', >> 'third_party/abseil-cpp/absl/strings/libabsl_strings.a', >> 'third_party/abseil-cpp/absl/synchronization/libabsl_synchronization.a', >> 'third_party/abseil-cpp/absl/time/libabsl_time.a' >> [ 93%] Built target protoc-gen-upb_minitable >> [ 94%] Building CXX object >> CMakeFiles/protoc.dir/src/google/protobuf/compiler/main.cc.o >> [ 94%] Linking CXX executable protoc >> ld: warning: ignoring duplicate libraries: >> 'third_party/abseil-cpp/absl/base/libabsl_base.a', >> 'third_party/abseil-cpp/absl/base/libabsl_log_severity.a', >> 'third_party/abseil-cpp/absl/hash/libabsl_hash.a', >> 'third_party/abseil-cpp/absl/log/libabsl_log_globals.a', >> 'third_party/abseil-cpp/absl/random/libabsl_random_distributions.a', >> 'third_party/abseil-cpp/absl/status/libabsl_status.a', >> 'third_party/abseil-cpp/absl/strings/libabsl_cord.a', >> 'third_party/abseil-cpp/absl/strings/libabsl_strings.a', >> 'third_party/abseil-cpp/absl/synchronization/libabsl_synchronization.a', >> 'third_party/abseil-cpp/absl/time/libabsl_time.a' >> >> >> Are there any plan to fix these minor issues? >> >> Thank you in advance! >> > -- 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 visit https://groups.google.com/d/msgid/protobuf/4a6e8967-e1ca-48e1-992b-fe706da11677n%40googlegroups.com.
