Add amalgamation source file

[behdad]

Add hb.cc that will include all base .cc files (easy) then make it actually compile (more work).

[behdad]

This works now!

Compile time is ~10s to 20s. I also see some measurable size improvement... Not jumping to conclusions just yet though.

Leaving open to 1. document in CONFIG.md, and 2. add bots that use it.

Note the resulting hb.cc doesn't add hb-ft.cc, hb-glib.cc, .. the integrations need to be added separately.

[behdad]

@drott @jfkthame FYI. I know Firefox already tries this itself. Might want to switch to this (when released).

[behdad]

cc @nona-google as well.

[ebraminio]

Niiiice

[drott]

Thanks, yes, in Chrome we call these "jumbo builds", and I think we have some tools in our .gn build files for this approach. But it's good if we can simplify our HarfBuzz build file. Are you testing both configurations on the CI bot, building the amalgamated and the regular files?

[behdad]

Are you testing both configurations on the CI bot, building the amalgamated and the regular files?

Not yet, but that's the plan indeed.

[ebraminio]

We can always use harfbuzz.cc in cmake which has the test suite, that way we don't have to modify autotools development and bots and make this test covered, deferring more to after meson migration.

[ebraminio]

Are you testing both configurations on the CI bot, building the amalgamated and the regular files?

As 9fea6b4 we now have harfbuzz.cc both build and test-suite checked in different cmake CI bots (including two Windows bots and bots testing all the shaping results tests), you will get some build/link time performance and size benefits also in Chrome (as it happened in harfbuzzjs) as the result I'd guess but harfbuzz.cc doesn't include subset files so you should include them separately, hmmm, maybe we should add those also when some compile flag is set, for now would be nice to test them in Chrome build but don't merge the change till the release so Behdad won't need to rush on the details.

[ebraminio]

harfbuzz.cc is released so let's close this, yay!

[ebraminio]

Filed https://crbug.com/995090 @drott this is being built with our cmake which is test covered so no worry about correctness AFAICT.