[`dot-shorthands`] inconsistent false positive `const_constructor_param_type_mismatch` (VSCode)

[RohitSaily]

this is not a flutter issue but the analysis problem is reproduced by invoking constructors from flutter

problem

controller.selection=.fromPosition(const .new(offset:1));

the const expression const .new(offset:1) gets flagged as error const_constructor_param_type_mismatch when it shouldn't, the default inputs to the constructor and the explicitly specified value 1 are all correct

for some reason, the error does not show up immediately. running the VSCode palette command Dart: Restart Analysis Server causes it to show up. if the expression is edited and then the file is saved the error goes away. after some time or by forcing reanalysis, it reappears

minimal reproduction

[1] pubspec.yaml

name: 'example'
publish_to: 'none'
environment:
  sdk: '^3.10.0-28.0.dev'
  flutter: '^3.33.0-1.0.pre-1146'
dependencies:
  flutter:
    sdk: 'flutter'

[2] analysis_options.yaml

analyzer:
  enable-experiment:
    - dot-shorthands

[3] main.dart

import 'package:flutter/widgets.dart';
void f(TextEditingController controller)
{	controller.selection=.fromPosition(const .new(offset:1));
}

[4] run VSCode palette command Dart: Restart Analysis Server (or otherwise trigger expression analysis)

---

editing and receiving errors via VSCode

dart --version

Dart SDK version: 3.10.0-28.0.dev (dev) (Thu Jul 24 09:03:49 2025 -0700) on "macos_x64"

flutter --version

Flutter 3.33.0-1.0.pre-1146 • channel main • https://github.com/flutter/flutter.git
Framework • revision 7de7baf2f1 (2 days ago) • 2025-07-27 18:01:28 -0400
Engine • hash c4f6c31864263c8d82ddc565c84501646c73138a (revision 7de7baf2f1) (36 hours ago) • 2025-07-27
22:01:28.000Z
Tools • Dart 3.10.0 (build 3.10.0-28.0.dev) • DevTools 2.48.0

[kallentu]

I can't actually repro this. I tried myself with a smaller example for the analyzer and it seems fine. We don't produce the const_constructor_param_type_mismatch error.

@bwilkerson Do you know why this happens: "for some reason, the error does not show up immediately. running the VSCode palette command Dart: Restart Analysis Server causes it to show up."? And if there's something I'm overlooking?

[bwilkerson]

No, I don't know. It's possible that there's some cached data that includes the diagnostic and the data isn't being flushed, but that's just a guess.

I was also not able to reproduce the problem. For the record, here's the code I used to try to reproduce the bug, but it doesn't produce any diagnostics:

void f(C controller) {
  controller.selection=.fromPosition(const .new(offset:1));
}

class C {
  set selection(D selection) {}
}

class D {
  D.fromPosition(P position);
}

class P {
  const P({required int offset});
}

@scheglov

[RohitSaily]

i also had trouble reproducing it without using flutter code. the example with the flutter code was the simplest i came up with

is anyone seeing the error when having the particular flutter code and then restarting analysis?

[bwilkerson]

Can you provide the smallest necessary wrapper to the statement in the original post that would make this valid Flutter code that exhibits the problem? (The reason I created what I did was because the statement can't be analyzed in isolation.)

[RohitSaily]

i'm sorry i am not sure what to provide, should i provide actually executable code with a main? otherwise wrapping it with a function and then reanalyzing via the VSCode palette command (with the pubspec and analysis options setup described in the first post) will produce the error

import 'package:flutter/widgets.dart';
void f(TextEditingController controller)
{	controller.selection=.fromPosition(const .new(offset:1));
}

[bwilkerson]

... should i provide actually executable code with a main?

Nope. What you provided is perfect, thanks. It just needs to be something we can paste in an empty file and be a valid Dart library, it doesn't need to be executable.