mozangle seems to be being built twice

[jrmuizel]

The first time we compile each file individually. The second time we pass all the files to a single cl instance. I don't yet understand why.

[jdm]

We build both a static library and a DLL in https://github.com/servo/mozangle/blob/e344a1b183e4f0f56486a900e5461eafc236635d/build.rs#L99-L121.

[jrmuizel]

Ah. Maybe we should only build one depending on the needs of the consumer? Also one of them doesn't build in parallel.

[jrmuizel]

Also, is it necessary to build twice to produce both outputs?

[jdm]

I honestly don't know. And yes, I would be open to adding features to control generation of the DLL and static libraries.

[jdm]

If you can figure out a way to get the DLL to build in parallel, that would be helpful. Building shared libraries has been declared outside the scope of the cc crate, unfortunately.

[jrmuizel]

It looks like this is causing the webrender CI to timeout which is preventing the github repo from being updated: https://github.com/servo/webrender/pull/3753#issuecomment-530606372. @jdm is it possible for you to make this double building behaviour opt in?