Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

cmd/compile: nonsensical error message with recursive generic interfaces #47837

Closed
4ad opened this issue Aug 20, 2021 · 3 comments
Closed

cmd/compile: nonsensical error message with recursive generic interfaces #47837

4ad opened this issue Aug 20, 2021 · 3 comments
Labels
NeedsInvestigation
Milestone

Comments

@4ad
Copy link
Member

@4ad 4ad commented Aug 20, 2021

This is a follow-up to #47836, see that issue first.

On tip (e9e0d1e) with -gcflags=-G=3.

Repro:

package p

type F[t F] interface {
	B() t
}

type Int0 int
type Int1 int

func (n Int0) B() Int1 { return Int1(n) }
func (n Int1) B() Int0 { return Int0(n) }

func id[t F[t]](v t) t { return v }

var _ = id(Int0(42))

Compiler rejects it with:

go build -gcflags=-G=3 j.go
# command-line-arguments
./j.go:15:11: Int0 does not satisfy F[t]: wrong method signature
	got  func (Int0).B() Int1
	want func (F[t ○string]).B() Int0
@mknyszek mknyszek added the NeedsInvestigation label Aug 20, 2021
@mknyszek mknyszek added this to the Go1.18 milestone Aug 20, 2021
@mknyszek
Copy link
Contributor

@mknyszek mknyszek commented Aug 20, 2021

CC @ianlancetaylor @griesemer

@griesemer griesemer self-assigned this Aug 22, 2021
@griesemer
Copy link
Contributor

@griesemer griesemer commented Aug 22, 2021

This is a type checker (types2) failure.

@griesemer
Copy link
Contributor

@griesemer griesemer commented Sep 24, 2021

The compiler is now correctly reporting an error:

cannot use generic type F[t invalid type] without instantiation

This was fixed as part of other fixes. Closing.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
NeedsInvestigation
Projects
None yet
Development

No branches or pull requests

3 participants