Improve dead code removal for object's empty methods

[yf-yang]

Describe the feature

const logger = { 
  info: () => {}, 
  log: x => console.log(x), 
  warn: x => console.log(x),
};
logger.info('abc');
// logger.log('def');
// logger.info('aaa');

playground link

When only one logger.log exists, in 1 pass, the code would be compiled to a chaining method call and blocks further dead code detection. When uncomment the second / the last two lines, 1 pass compiled codes are different and lead to different multi pass compiled code.

Terser could work more stable in this scenario. You can copy the code to https://try.terser.org/ and configure compress.passes to 1/2/3 to see how it is different from SWC.

Not a bug, but I hope it could be improved, so that I can remove lots of strings logged by logger in out app with SWC's minimizer.

Thank you!

Babel plugin or link to the feature description

No response

Additional context

No response

[CPunisher]

Investigation:
Currently this optimization is prevented by the following code, where self.ctx.is_callee is true.

swc/crates/swc_ecma_minifier/src/compress/optimize/props.rs

Line 251 in fa80a1e

if self.ctx.is_update_arg || self.ctx.is_callee || self.ctx.is_exact_lhs_of_assign {

We can find the corresponding check in terser at: https://github.com/terser/terser/blob/3167d34557d9bbf6394b468605169e7f9648594a/lib/compress/index.js#L3716C66-L3716C79
where the restriction is released with !has_annotation(parent, _NOINLINE) (which is usually true).

We can make it by add a new is_noline context. However, to keep the this pointer in the inlined function correct, we also need to add a safety check: https://github.com/terser/terser/blob/3167d34557d9bbf6394b468605169e7f9648594a/lib/compress/index.js#L3475

The only problem is that when the value of the property is Ident(AST_SymbolRef), we have not collected the fixed expr of all idents but those to be inlined. So for now, by the above, we can only optimize ({ f: (x) => console.log(x) }).f(1) to console.log(1), but we can't optimize:

const f = (x) => console.log(x);
console.log(f); // another reference that prevents minifier inlining f
({ f: f }).f(1);

[yf-yang]

Thank you for your investigation. I don't quite understand "the only problem" you are talking about, could

const g = (x) => console.log(x);
({ f: g }).f(1);

and

const f = (x) => console.log(x);
({ f: f }).f(1);

be compressed?

IMHO it is perfectly fine that it could not be compressed if the function is referenced somewhere else. That's just a corner case.

And, without considering those corner cases, I hope it could deal with simpler cases like:

const logger = { 
  info: () => {}, 
  log: () => {}, 
  warn: () => {}, 
};
logger.info('abc');
logger.info('abc');
logger.log('def');
logger.warn('fgh');

and

const logger = { 
  info: () => {}, 
  log: () => {}, 
  warn: () => {}, 
};
logger.info('abc');

Those cases are not working for the moment.