Dead-code removal not working on return expressions

[manucorporat]

• Rollup Version: 1.9.0
• Operating System (or Browser): osx and browser

How Do We Reproduce?

I am not sure about the root of the problem, but we hit the issue when we try to treeshake part of the stencil's runtime using a object of constant booleans.

https://rollupjs.org/repl?version=1.9.0&shareable=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

Replacing BUILD with true directly, removes the dead-code properly.

Expected Behavior

Input:

const BUILD = true;

export const bar = () => {
    console.log(foo());
};

const foo = () => {
	return BUILD ? A : B;
};

Should generate

const bar = () => {
    console.log(foo());
};

const foo = () => {
	return A;
};

export { bar };

Actual Behavior

const BUILD = true;

const bar = () => {
    console.log(foo());
};

const foo = () => {
	return BUILD ? A : B;
};

export { bar };

The constant expression is not dropped

[lukastaegert]

For now this is an ordering issue. If you switch the order of the definitions of foo and bar, it will work correctly. Will check if there is a simple way of improving it without introducing a second bind pass...

[lukastaegert]

The fix was surprisingly easy, see #2803