编译错误

[JohnQI8888]

gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/11/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 11.4.0-1ubuntu122.04' --with-bugurl=file:///usr/share/doc/gcc-11/README.Bugs --enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++,m2 --prefix=/usr --with-gcc-major-version-only --program-suffix=-11 --program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-plugin --enable-default-pie --with-system-zlib --enable-libphobos-checking=release --with-target-system-zlib=auto --enable-objc-gc=auto --enable-multiarch --disable-werror --enable-cet --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none=/build/gcc-11-XeT9lY/gcc-11-11.4.0/debian/tmp-nvptx/usr,amdgcn-amdhsa=/build/gcc-11-XeT9lY/gcc-11-11.4.0/debian/tmp-gcn/usr --without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu --with-build-config=bootstrap-lto-lean --enable-link-serialization=2
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 11.4.0 (Ubuntu 11.4.0-1ubuntu122.04)

uname -a

Linux aaa-virtual-machine 6.2.0-35-generic #35~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Fri Oct 6 10:23:26 UTC 2 x86_64 x86_64 x86_64 GNU/Linux

What happened + What you expected to happen

cmake -B build && cmake --build build -j

                                    ;

:3:
/home/aaa/co_context/include/co_context/co/when_all.hpp:94:24: error: missing 'typename' prior to dependent type name 'meta_type::value_type'
using value_type = meta_type::value_type;
^~~~~~~~~~~~~~~~~~~~~
typename
:104:65: error: use of undeclared identifier 'variant_type'
std::conditional_t<is_all_void, index_type, index_value<variant_type>>;
^
In file included from In file included from In file included from /home/aaa/co_context/example/echo_server_MT.cpp:2:
In file included from /home/aaa/co_context/include/co_context/net.hpp:4:
/home/aaa/co_context/include/co_context/co/when_any.hpp:106:32: error: use of undeclared identifier 'variant_type'
using meta_type = any_meta<variant_type>;
^
In file included from /home/aaa/co_context/example/when_all.cpp:1:
In file included from /home/aaa/co_context/include/co_context/all.hpp:10:
In file included from /home/aaa/co_context/include/co_context/net.hpp:3:
/home/aaa/co_context/include/co_context/co/when_all.hpp:69:/home/aaa/co_context/example/echo_server.cpp:1:
In file included from /home/aaa/co_context/include/co_context/net.hpp:4:
fatal error: /home/aaa/co_context/include/co_context/co/when_any.hpp:104:65: error: use of undeclared identifier 'variant_type'
std::conditional_t<is_all_void, index_type, index_value<variant_type>>;
^

Reproduction way

Anything else

[Codesire-Deng]

相信这是一个编译器 BUG，因为 C++20 标准 已经降低了对 typename disambiguator for dependent names 的要求，项目在 gcc 11.2.1 中编译也没有问题。

我已经在 main 分支中添加了更多 typename，希望能绕开这个编译问题。

[JohnQI8888]

所以 我怎么做？ 用最新的版本 重新编译 可以了吗？

我希望完成一个demo 可以 计算一下一个协程切换使用的时间长度， 你是否可以给与一些帮助？

[Codesire-Deng]

所以 我怎么做？ 用最新的版本 重新编译 可以了吗？

是的。git pull 之后尝试重新编译就行。

我希望完成一个demo 可以 计算一下一个协程切换使用的时间长度

项目里有这个测试，如果你的系统安装了 google benchmark (包名大概就是"benchmark")，可以按以下步骤编译运行:

cmake -B build/release --preset benchmark
cmake --build build/release -j
build/release/test/benchmark/co_await # 测量 C++20 co_await 的最低耗时
build/release/test/benchmark/lazy_yield # 测量 co_context 的调度耗时

如果你想自己写 benchmark，可以参考这个源文件：
test/benchmark/co_await.cpp

[Codesire-Deng]

顺便一提，上述 benchmark 在我的环境下(wsl2, i5-12600KF)，co_await 平均延迟是 2.5ns；lazy_yield 的延迟是 2.5~3.2ns。