tune "convert to set literal" assist to avoid producing code w/ type errors

[pq]

In the world of set-literals, an assist is presented on this snippet.

Set<String> s = new HashSet<String>();

If you perform it, and get:

Set<String> s = <String>{};

which provokes the following error:

error: The set literal type 'Set<String>' isn't of expected type 'HashSet<String>'. The set's type can be changed with an explicit generic type argument or by changing the element types. (strong_mode_invalid_cast_literal_set at ...)

As discussed in #57905, we should consider not providing the assist if it would produce errored results.

/cc @bwilkerson

[leafpetersen]

I don't think that's the example you mean - that fix should not cause an error. Perhaps you mean that the original code was:

 HashSet<String> s = new HashSet<String>();

?

[bwilkerson]

I just confirmed that Set<String> s = <String>{}; does not produce any error, while HashSet<String> s = <String>{}; does produce an error.

However, as far as I can tell, the assist is only offered if the explicitly created type is Set, not when it is either HashSet or LinkedHashSet.

[pq]

@leafpetersen: you're spot on. Sorry for the confusion. I've been juggling a lot of cases and got this one mixed up.

However, as far as I can tell, the assist is only offered if the explicitly created type is Set, not when it is either HashSet or LinkedHashSet.

And it looks doubly so. You're right @bwilkerson. The assist does the right thing.

Closing this out. Feel free to re-open if there's anything of value here.

Thanks!