focal_loss_cuda.obj : error LNK2001: 无法解析的外部符号 "public: long __cdecl at::Tensor::item<long>(void)const " (??$item@J@Tensor@at@@QEBAJXZ) build\lib.win-amd64-3.8\mmdet\cv_core\_ext.cp38-win_amd64.pyd : fatal error LNK1120: 1 个无法解析的外部命令

[ouening]

OS: Win10
CUDA: 11.0
pytorch: 1.7.1+cu110
python: 3.8

编译mmdetection-mini时出现了以下错误：

LIB:build\temp.win-amd64-3.8\Release\./mmdet/cv_core/ops/csrc/pytorch\_ext.cp38-win_amd64.lib
  正在创建库 build\temp.win-amd64-3.8\Release\./mmdet/cv_core/ops/csrc/pytorch\_ext.cp38-win_amd64.lib 和对象 build\temp.win-amd64-3.8\Release\./mmdet/cv_core/ops/csrc/pytorch\_ext.cp38-win_amd64.exp
focal_loss_cuda.obj : error LNK2001: 无法解析的外部符号 "public: long __cdecl at::Tensor::item<long>(void)const " (??$item@J@Tensor@at@@QEBAJXZ)
build\lib.win-amd64-3.8\mmdet\cv_core\_ext.cp38-win_amd64.pyd : fatal error LNK1120: 1 个无法解析的外部命令
error: command 'C:\\Program Files (x86)\\Microsoft Visual Studio\\2019\\Community\\VC\\Tools\\MSVC\\14.28.29333\\bin\\HostX86\\x64\\link.exe' failed with exit status 1120

windows下的mmcv-full已经在mmcv的讨论open-mmlab/mmcv#709 (comment) 中实现了编译安装。mmdetection是可以正常编译的。