Build optimizer breaks third party libraries

[yGuy]

Bug Report or Feature Request (mark with an x)

- [x] bug report -> please search issues before submitting
- [ ] feature request

Area

- [x] devkit
- [ ] schematics

Versions

all

Repro steps

• Scaffold a project that uses code (e.g. a third party library) that contains code that cannot be properly "optimized" using uglifyjs. E.g. code that uses "non-pure getters" like this:

let object = {};
Object.defineProperty(object,"nonSideEffectFreeGetterBasedMember", 
    {get: function(){ console.log("side effect")}});

(function () {
  object.nonSideEffectFreeGetterBasedMember;
}());

• Enable the angular build optimizer
• Run the program with the build optimizer enabled and observe that the code does not work as expected anymore, because the non-pure getter has been removed and the side-effect does not happen anymore.

The log given by the failure

n/a

Desired functionality

It should be possible to either configure the build optimizer and disable possibly logic-breaking optimizations altogether or at least on a per dependency basis. Especially if the third party library is already optimized/minified/preprocessed the danger of breaking things is higher than the benefits of possibly saving a few more bytes.

Mention any other details that might be useful

Right now it is an either/or - either the code runs and you can rely on it, or it may be "optimized" but broken in some cases.

The tool-chain makes it easy to include all kind of packages from third parties via npm, etc. The "build-optimizer" cannot dictate how the code of all of these packages needs to be written in order to work with the "optimization" step. It's OK to forbid non-pure getters in the angular code base, but not in any third party code. Either add an option to only apply safe code transformations for third party code or make this an opt-in. The binary API right now is not sufficient.

[seanbright]

I'm experiencing this as well with https://github.com/onsip/SIP.js as a dependency. Building with Angular CLI without the --prod flag my application works, with the --prod flag it doesn't. No errors are emitted, so it seems that something is just getting silently optimized away.

[alexeagle]

This issue was moved to angular/angular-cli#12128