[build-optimizer] Ivy code is not full tree shaken / marked @PURE

[hansl]

Building an app with Ivy and optimizations on, I see the following code still there:

Before Uglify:

var NgModuleFactory$1 = /** @class */ (function (_super) {
    __extends(NgModuleFactory$$1, _super);
    function NgModuleFactory$$1(moduleType) {
        var _this = _super.call(this) || this;
        _this.moduleType = moduleType;
        return _this;
    }
    NgModuleFactory$$1.prototype.create = function (parentInjector) {
        return new NgModuleRef$1(this.moduleType, parentInjector);
    };
    return NgModuleFactory$$1;
}(NgModuleFactory));

After Uglify (with mangle off):

        !function(_super) {
            function NgModuleFactory$$1(moduleType) {
                var _this = _super.call(this) || this;
                return _this.moduleType = moduleType,
                _this
            }
            __extends(NgModuleFactory$$1, _super),
            NgModuleFactory$$1.prototype.create = function(parentInjector) {
                return new NgModuleRef$1(this.moduleType,parentInjector)
            }
        }(function() {}),

We would expect the first snippet to have a @PURE annotation on it following the @class, and the function not to be there at all after uglify.

[hansl]

Seems like we don't use the @class annotation as hint to add @PURE, which we should.

[kzc]

On a hunch I searched for __extends in the repo. It may be due to the \w+ in this regex:

angular-cli/packages/angular_devkit/build_optimizer/src/transforms/prefix-classes.ts

Line 30 in 44086c6

/\w*\.?__extends\(\w+, _super\);/,

\w+ doesn't match the $ character in the bundler renamed NgModuleFactory$$1.

$ node -p '/\w*\.?__extends\(\w+, _super\);/.test("__extends(NgModuleFactory$$1, _super);")'
false

Possible alternatives: \S+ or [A-Za-z_$][A-Za-z0-9_$]*.

$ node -p '/\w*\.?__extends\(\S+, _super\);/.test("__extends(NgModuleFactory$$1, _super);")'
true

$ node -p '/\w*\.?__extends\([A-Za-z_$][A-Za-z0-9_$]*, _super\);/.test("__extends(NgModuleFactory$$1, _super);")'
true

[filipesilva]

Yeah I think this was the renamed class. 07ceb05 fixed a similar thing.

The "gatekeeper" regex didn't correctly identify it though, for the reasons highlighted by @kzc. #13613 should fix it.

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