Latest version overwrites more environment than necessary

Version 1.7 only set environment variables that matched certain patterns. Version 1.8 sets all variables set by vcvarsall. This caused a failure on my application because the earlier code wouldn’t set the PLATFORM variable, but the new code does (it would set it in a case-insensitive system, since “Platform” was one of the extracted variables).

I’m not sure that the new way is worse, but I’m leaving this here in case someone else is scratching their head trying to figure out what’s up.

[ilammy]

@abellgithub, uhh… Yeah, I have not foreseen such issue. I’m sorry for breaking your build. I believe you can work around this issue for now by using the 1.7 version, right?

@pzhlkj6612, on Windows environment variables are case-insensitive. So if the build already defines PLATFORM for its own unrelated purpose then msvc-dev-cmd would overwrite that value when it tries to set Platform because vcvarsall.bat wants that. And this will make the build upset.

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Well, I guess what could be useful is to have a way to give users some control over what variables this action may or may not overwrite and set. For example, like this:

- uses: ilammy/msvc-dev-cmd@v1
  with:
    set-only-these-variables:
      - PATH
      - INCLUDE
      - LIBDIR

or like this:

- uses: ilammy/msvc-dev-cmd@v1
  with:
    never-touch-these-variables:
      - PLATFORM

(with variable names matched case-insensitively).

That way if one needs only some variables, they can ask only for them. If one already uses some variables and would not want MSVC to overwrite them, they could achieve that too.

[ilammy]

@pzhlkj6612, thanks for your analysis.

It slipped my mind that Platform was in the original list of exported variables. So it’s just pure luck that PLATFORM did not get overwritten in v1.7 – if I had not forgotten about case-insensitivity of the variables and coded it ‘correctly’ then it would have still been overwritten. What a weird quirk.

I’m sorry that I didn’t fully understand the code and asked some silly questions

There’s nothing to be sorry for. That’s how people learn. And you point out things that other people miss.

By the way, would you be interested in cooking a patch that lets the users to include/exclude certain variables? I think it wouldn’t hurt to have this feature, just in case. And it could be a nice exercise to implement.