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

mozangle/build.rs

Lines 99 to 121 in e344a1b

	// Build DLL.
	let mut cmd = build.get_compiler().to_command();
	let out = env::var("OUT_DIR").unwrap();
	let out = Path::new(&out);
	cmd.arg(out.join("angle.lib"));
	for lib in data.os_libs {
	cmd.arg(&format!("{}.lib", lib));
	}
	for file in data.sources {
	cmd.arg(fixup_path(file));
	}
	cmd.arg("/LD");
	cmd.arg(&format!("/Fe{}", out.join("libEGL").display()));
	cmd.arg("/link");
	cmd.arg("/DEF:gfx/angle/checkout/src/libEGL/libEGL.def");
	let status = cmd.status();
	assert!(status.unwrap().success());
	// Build lib.
	build.compile("EGL");

.

[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: servo/webrender#3753 (comment). @jdm is it possible for you to make this double building behaviour opt in?