[Build][Windows] Fix Windows build by including cctype

[soiferj]

The Windows build is currently broken with the error: isdigit is not a member of standard. It looks like std::isdigit is in header <cctype>. Including it fixes the build.

@tqchen @jmorrill could you take a look?

Also, is there an ETA to get the Azure build pipeline back up?

[jmorrill]

With the latest source from master, I do not get any build errors on the CMake generated tvm.sln.

I am using Visual Studio 2019 (cl.exe version 19.23.28106.4). What version are you using?

FWIW, your patch doesn't have any negative effects on my build ;)

[soiferj]

I'm using VS 2017 (cl version 19.16.27032.1). Where does your compiler get std::isdigit from?

I think we should still check this in for safety.

[jmorrill]

I'm using VS 2017 (cl version 19.16.27032.1). Where does your compiler get std::isdigit from?

I believe mine is getting it from cctype also. Could Microsoft have refactored some other std header in 2019 that inadvertently includes cctype?

If that is the case I would agree with checking it in for safety.

[jmorrill]

I compiled file \tvm\nnvm\src\top\tensor\transform.cc with /showIncludes because it uses std::isdigit and found the only reference to cctype here:

1>Note: including file:    C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.23.28105\include\string
1>Note: including file:     C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.23.28105\include\cctype

Appears 'string' is pulling in cctype with 2019?

[jmorrill]

Ok thats it. string pulls in cctype in VS2019 and does not in 2017

Following builds in 2019 and does not in 2017.

#include <iostream>
#include <string>

int main()
{
    auto x = std::isdigit('5');
    std::cout << "Hello World!\n";
}

[soiferj]

Thanks a lot for the investigation - that's a useful finding. There should be no harm in adding this include :)

[soiferj]

@tqchen looks like there's a CI error impacting all PRs. It just says "process terminated". Is this a known issue?

[tqchen]

Hmm, would due to CI overloaded and throttling and timeout, I will look into this.

[yzhliu]

Thanks @soiferj @jmorrill @tqchen