Angular: use the aot compiler for ng build

[Jane Sandberg]

Currently, `ng build --prod` uses the ahead-of-time (AOT) compiler, while `ng build` uses the just-in-time (JIT) compiler.

As of angular 9, the angular documentation recommends using the AOT compiler for both: https://angular.io/guide/ivy

This would provide a bit more consistency for developers (since some errors only display in AOT, others only display in JIT, and we want to make sure that the AOT in particular is error-free so that builds don't break).

Branch forthcoming.

[Jane Sandberg (sandbergja)]

Branch available for your review at user/sandbergja/lp1895395_ng_build_aot

Here's a link: https://git.evergreen-ils.org/?p=working/Evergreen.git;a=shortlog;h=refs/heads/user/sandbergja/lp1895395_ng_build_aot

[Bill Erickson (berick)]

Hi, while I agree with this in theory, it will add a significant roadblock to speedy development. My dev VM is currently taking about 22 seconds to compile after each change, compared to JIT which is practically instantaneous. There will be times, especially early in the dev process for an interface, where AOT has to be disabled.

If we can force JIT via command line, it's probably fine. We may need to publicize this capability and provide some guidance on when/if to us it.

My approach thus far has been to do all development with JIT then do my final testing with AOT, fwiw.

[Galen Charlton (gmc)]

Pushed for inclusion in 3.6. Thanks, Jane!

[Galen Charlton (gmc)]

In light of Bill's comments, I'm taking another look at this.

[Galen Charlton (gmc)]

OK, for me it was the difference between 0.8 seconds and 2 seconds, which wasn't enough to matter, but on the other hand the box I was using had plenty of memory and was all SSD. I've gone ahead and pushed a revert pending further discussion. Apologies for jumping the gun.

[Galen Charlton (gmc)]

As far as the command line is concerned, it looks like the following works to override the angular.json setting when Jane's patch is applied:

ng build --watch --aot false