"Make final" fix puts "final" in the wrong position in record destructuring

[DanTup]

I have the prefer_final_locals lint enabled which triggers on this code individually for both kind and value:

    for (var (kind, value) in sensorValues) {

However the quick-fix inserts final before the variable name producing invalid code:

for (var (final kind, value) in sensorValues) {

I thought it should change var to final instead, although that affects more than just the variable where the fix was invoked. This led me to try the following:

for (var (kind, value) in sensorValues) {
  value = 1;

Here, the lint still fires for kind, but I don't know what I'd expect the fix to do here. Perhaps the lint should only fire if all declared variables can be changed to final? Or is there some way to destructure into a mix of final/non-final variables?

[scheglov]

@pq

[pq]

Here, the lint still fires for kind, but I don't know what I'd expect the fix to do here. Perhaps the lint should only fire if all declared variables can be changed to final?

That's my instinct exactly. We do make that call elsewhere so I think this is a bug. (Filed: dart-lang/linter#4539.)

[DanTup]

If it's fixed in that way, I presume there's nothing to change in the fix (and should close this issue?)

[bwilkerson]

Even in cases where all of the variables can be final, such as

void f(List<(int, int)> sensorValues) {
  for (var (kind, value) in sensorValues) {
    print(kind);
    print(value);
  }
}

the fix still puts the 'final' in the wrong place. I think the fix still needs to be fixed.

[DanTup]

Oh yeah, whoops. That was my original issue, I confused myself with the tangent 🙃

[pq]

I'm grateful that you brought it up. It's a legitimate false positive in the lint. Thanks for catching it!