proposal: `provide_const_constructors`

[dleurs]

provide_const_constructors

• Adding const for constructor definition when possible, inside the class
• Currently prefer_const_constructors only check const when class is called, and so only when constructor definition is already const.

Description

BAD:

class A {
  A();
}

GOOD:

class A {
  const A();
}

Links :

• StackOverFlow: https://stackoverflow.com/questions/76960007/dart-analyser-const-on-constructor-inside-the-class?noredirect=1#comment135670187_76960007
• Previous proposal of extending prefer_const_constructors proposal: add constructor to prefer_const_constructors #59267

[pq]

In your use case, if it's reasonable to mark your classes as @immutable, you might consider using prefer_const_constructors_in_immutables?

[dleurs]

I can but could be great if it was not necessary

[EArminjon]

Could be a great feature. We are looking for a way to encourage our developers through a linter rule to use a const constructor when possible. If they forget @immutable, we will have the same issue.

No linter issue here :

In addition, linter didn't warn to add const constructor when we use @immutable :

Linter only warn if @immutable is used and constructor is present :

[sagar-tide]

It would be really helpful to get this lint warning without having to annotate classes with @immutable

[bwilkerson]

Linter only warn if @immutable is used and constructor is present :

That seems like a bug that should be fixed.

We are looking for a way to encourage our developers through a linter rule to use a const constructor when possible.

I'm not being facetious, but the question I have is: why?

Making widgets be const objects improves performance because the repaint mechanism uses identity to trim unnecessary work. But unless you are depending on identity, or unless you need canonicalization in order to lower your memory use, making everything const doesn't necessarily bring any value. I'd be interested in knowing why you think it brings value to use const everywhere that it's possible to do so.