[MetaSchedule] Include te/tensor.h instead of forward declaring te::T…

[kparzysz-quic]

…ensor

ApplyHistoryBestNode declares an Array of Tensor. There are type traits used in Array that require that the element type is complete at the time of the declaration. With only a forward declaration compilation fails (clang 14.0.3, libc++).

[junrushao]

Thanks for spotting this!! I will definitely pay more attention here

[junrushao]

Lesson learned here for me is that never do forward declaration if we can simply include a header :-)

[kparzysz-quic]

It's actually a good practice to use forward declarations when the header is not needed. The problem is that in some cases the types must me complete, in this case it was because there was std::enable_if used in the declaration of Array. The trait checked in there required the checked type to be complete.
What I find surprising that it works with the compilers we use in CI. I'm not sure of this is because of newer clang, or because I'm using libc++.

[junrushao]

@kparzysz-quic Yeah I just verified with clang 14:

>>> clang++-14 --version
Ubuntu clang version 14.0.5-++20220603124341+2f0a69c32a4c-1~exp1~20220603124352.149
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin

but yet cannot reproduce the compilation issue...so i guess probably it's something with libc++

[kparzysz-quic]

Try setting -DCMAKE_CXX_FLAGS='-stdlib=libc++'.