create dmd "light" installer on windows

[rainers]

• grabs mingw from it's repository
• builds import libraries from mingw definition files
• builds stub for msvcr100.dll
• creates installer using these sdk libraries and lld-link

I couldn't test build_all though because it only runs on linux.

I'm also a bit confused about the use of the create_dmd_release_extra folder: it seems they do not end up in the result directory/zip. Instead link.exe is expected create_dmd_release\extras\dmd2\windows\bin, not in the additional extras. So what's the point of the committed extra folders?

This depends on dlang/tools#267
The dmd/phobos sources should have dlang/dmd#7261 and dlang/phobos#5839 applied.

[dlang-bot]

Thanks for your pull request, @rainers!

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[MartinNowak]

Great, I'll try to test and review this for the upcoming beta.
The additional extras was necessary to copy over binary-only tools, like obj2asm.

[MartinNowak]

Can we find a more descriptive name for this toolchain @rainers ? How about dmd-lld?
Also this should get a changelog entry, describing this (and an experimental warning I guess).

Just copy the changelog/README.md from dmd or so, installer changelogs are already supported.
https://github.com/dlang/tools/blob/40b1efb88550c6a2daea2b8c2d03177a502ce684/changed.d#L409

[MartinNowak]

Should we try to integrate this with the normal dmd installer right away? Adding more choices might cause unnecessary confusion.

[rainers]

Should we try to integrate this with the normal dmd installer right away?

It's probably the simplest way to get people to test it.
The installer in this PR also includes the "sdk" in the normal distribution, there's just a different default sc.ini.
The VS auto-detection has been merged (dlang/dmd#7393), if we include lld and the "light sdk", it should be added to the auto-detection mechanism, too.

[MartinNowak]

I'm for integrating this as a VC fallback with the normal release (for -m32mscoff, -m64).

[rainers]

I'm for integrating this as a VC fallback with the normal release (for -m32mscoff, -m64).

Done in #281. Closing in favor of that.