Different empty interfaces are mutually incompatible (under 6g)

[gopherbot]

by punya.biswal:

What steps will reproduce the problem?

1. Try to create a heap with an underlying vector. (See attached source for 
details).

What is the expected output? What do you see instead?

It doesn't compile because *vector.Vector isn't heap.Interface (in 
particular, vector.Vector has Push(x vector.Element) and heap.Interface 
wants Push(x interface { }). This is odd because vector.Element is itself 
an empty interface.

What is your $GOOS?  $GOARCH?
GOOS=linux
GOARCH=amd64

Which revision are you sync'ed to?  (hg log -l 1)

3975:b51f...
Please provide any additional information below.

Attachments:

1. element.go (236 bytes)

[rsc]

Comment 1:

The central issue here is that
func Push(vector.Element)
func Push(interface{})
are different types according to the language specification.
Similarly, if you had
type T int
then you could not use a method Add(T) to satisfy Add(int):
they're different types, which can be useful but is certainly
different from, say, C or C++.
The best answer to this might be to replace vector.Element
with interface{}.

Status changed to Accepted.

[gopherbot]

Comment 2 by punya.biswal:

Just to make sure that I understand you correctly: is the recommended way to accomplish 
what I want to wrap vector.Vector in my own type and implement a bunch of pass-through 
methods in addition to the one thing I want to change?

[griesemer]

Comment 3:

Owner changed to g...@golang.org.

[griesemer]

Comment 4:

This issue was closed by revision 23843fa.

Status changed to Fixed.

Merged into issue #-.

[griesemer]

Comment 5:

Your attached source now compiles w/o problems. Please send e-mail to golang-nuts for
questions about how 
to use it. Thanks.

[gopherbot]

Comment 6 by punya.biswal:

Thanks for the speedy fix!