Tree-shaking: Destructuring assignment not recognised as side-effect

[kachurun]

• Rollup Version: 2.4.0
• Link to reproduction (IMPORTANT, read below):
  https://rollupjs.org/repl/?version=2.40.0&shareable=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

Expected Behavior

test() {
  this.a;	// Side-effects
  this.b; // SIde-effects
  this.c; // SIde-effects

  // return { a, b, c };
}

Actual Behavior

test() {
  this.a;	// Side-effects
  this.b; // SIde-effects
  
  // return { a, b, c };
}

[kzc]

related bug: #2219

[kzc]

fwiw, Removing the getters for a and b produces the same code for the test method as the top post.

$ cat main.js
const obj = {
	get c() {
		console.log('side-effect C')
	},
	test() {
		this.a;
		const b = this.b
		const { c } = this
	}
}
obj.test()

$ cat main.js | rollup --silent
const obj = {
	get c() {
		console.log('side-effect C');
	},
	test() {
		this.a;
		this.b;
	}
};
obj.test();

[kzc]

--treeshake.propertyReadSideEffects=always can now be used as a workaround for tree shaking with getters with side effects.