8000 Shadowing class generics with method generics is confusing · Issue #33956 · dart-lang/sdk · GitHub
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Shadowing class generics with method generics is confusing #33956

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matanlurey opened this issue Jul 23, 2018 · 5 comments
Closed

Shadowing class generics with method generics is confusing #33956

matanlurey opened this issue Jul 23, 2018 · 5 comments
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area-language Dart language related items (some items might be better tracked 8000 at github.com/dart-lang/language). closed-stale Closed as the issue or PR is assumed stale

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@matanlurey
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Reproduction case:

class Foo<T> {
  void addValues<T>(Iterable<T> values) {}
}

This causes a compile-time error:

[error] The argument type 'Iterable<T> (dart:core/iterable.dart)' can't be assigned to the parameter type 'Iterable<T> (dart:core/iterable.dart)'.

That's because the T's are different...

I do not know where to assign this (language? cfe? analyzer?)
@jonahwilliams
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There is a similar issue in typedefs, I'm not sure if it has already been brought up:

// The T in Function shadows the T in the name.
MyCallback<T> = Function<T>(T);
// Correct version.
MyCallback2<T> = Function(T);

For example, in 2.0.0-dev.68.0 the following code produces the analyzer error:
A value of type '(String) → void' can't be assigned to a variable of type '<T>(T) → void' at main.dart:7:23 • invalid_assignment

MyCallback<T> = Function<T>(T);

void main() {
  MyCallback<String> bar = foo; 
}

void foo(String value) {}

@vsmenon
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vsmenon commented Jul 24, 2018

@matanlurey I'm not getting a compile error on your snippet of code (2.0.0-dev.69.2).

@srawlins
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Lol see #57713 also

@matanlurey
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matanlurey commented Jul 24, 2018 •
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@vsmenon Really? I see it internally, in DDC. Unless this was just fixed.

@a-siva a-siva added the area-language Dart language related items (some items might be better tracked at github.com/dart-lang/language). label Aug 14, 2018
@lrhn lrhn closed this as completed Apr 9, 2025
@lrhn lrhn added the closed-stale Closed as the issue or PR is assumed stale label Apr 9, 2025
@eernstg
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eernstg commented Apr 9, 2025

Should be covered by this one: https://dart.dev/tools/linter-rules/avoid_shadowing_type_parameters.

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@srawlins @matanlurey @vsmenon @lrhn @a-siva @jonahwilliams @eernstg
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