fix(ngcc): handle new __spreadArrays tslib helper

[alan-agius4]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/angular/angular/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• angular.io application / infrastructure changes
• Other... Please describe:

What is the current behavior?

Issue Number: #33614

What is the new behavior?

We already have special cases for the __spread helper function and with this change we handle the new tslib helper introduced in version 1.10 __spreadArrays.

For more context see: https://github.com/microsoft/tslib/releases/tag/1.10.0

Fixes: #33614

Does this PR introduce a breaking change?

• Yes
• No

Other information

[JoostK]

Awesome, thanks! ❤️

Could you please change the commit scope into ngcc, we have it as dedicated scope.

[alan-agius4]

@JoostK. commit scope changed.

Thanks for the review.

[petebacondarwin]

Should we consider evaluating SpreadArrays differently, given that this was introduced because the two scenarios emit different downlevelled code?

[petebacondarwin]

function spreadArrays() {
  for (var s = 0, i = 0, il = arguments.length; i < il; i++) s += arguments[i].length;
  for (var r = Array(s), k = 0, i = 0; i < il; i++)
    for (var a = arguments[i], j = 0, jl = a.length; j < jl; j++, k++)
      r[k] = a[j];
  return r;
}

function spread() {
  for (var ar = [], i = 0; i < arguments.length; i++) ar = ar.concat(__read(arguments[i]));
  return ar;
}

Our current helper does this:

function evaluateTsSpreadHelper(node: ts.Node, args: ResolvedValueArray): ResolvedValueArray {
  const result: ResolvedValueArray = [];
  for (const arg of args) {
    if (arg instanceof DynamicValue) {
      result.push(DynamicValue.fromDynamicInput(node, arg));
    } else if (Array.isArray(arg)) {
      result.push(...arg);
    } else {
      result.push(arg);
    }
  }
  return result;
}

[petebacondarwin]

I guess that if the arg is already an array then it has been dealt with elsewhere and any downlevelling of the iterator is irrelevant.

[atscott]

presubmit
ivy presubmit

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