code review 11189043: go.tools/go/types: export IsAssignableTo

go.tools/go/types: export IsAssignableTo

Tested implictly since its simply calling the
internal isAssignableTo which is used in every
assignment when testing the std library.

[gri, 2013-07-11 21:05:49]

Hello adonovan@google.com (cc: golang-dev@googlegroups.com),

I'd like you to review this change to
https://code.google.com/p/go.tools

[adonovan, 2013-07-11 21:08:53]

On 2013/07/11 21:05:49, gri wrote:
> Hello mailto:adonovan@google.com (cc: mailto:golang-dev@googlegroups.com),
> 
> I'd like you to review this change to
> https://code.google.com/p/go.tools

LGTM

[adonovan, 2013-07-11 21:08:57]

https://codereview.appspot.com/11189043/diff/6001/go/types/api.go
File go/types/api.go (right):

https://codereview.appspot.com/11189043/diff/6001/go/types/api.go#newcode156
go/types/api.go:156: func IsAssignableTo(V, T Type) bool {
Is this an invariant:
forall iface *Interface, conc Type. MissingMethod(iface, conc) == nil <=>
isAssignableTo(conc, iface)
?

Does it warrant a test?

[gri, 2013-07-11 21:20:54]

https://codereview.appspot.com/11189043/diff/6001/go/types/api.go
File go/types/api.go (right):

https://codereview.appspot.com/11189043/diff/6001/go/types/api.go#newcode156
go/types/api.go:156: func IsAssignableTo(V, T Type) bool {
On 2013/07/11 21:08:57, adonovan wrote:
> Is this an invariant:
> forall iface *Interface, conc Type. MissingMethod(iface, conc) == nil <=>
> isAssignableTo(conc, iface)
> ?
> 
> Does it warrant a test?

Yes, there is explicit code in isAssignableTo:

	// T is an interface type and x implements T
	// (Do this check first as it might succeed early.)
	if Ti, ok := Tu.(*Interface); ok {
		if m, _ := MissingMethod(x.typ, Ti); m == nil {
			return true
		}
	}

[adonovan, 2013-07-11 21:22:43]

LGTM

On 2013/07/11 21:20:54, gri wrote:
> https://codereview.appspot.com/11189043/diff/6001/go/types/api.go
> File go/types/api.go (right):
> 
> https://codereview.appspot.com/11189043/diff/6001/go/types/api.go#newcode156
> go/types/api.go:156: func IsAssignableTo(V, T Type) bool {
> On 2013/07/11 21:08:57, adonovan wrote:
> > Is this an invariant:
> > forall iface *Interface, conc Type. MissingMethod(iface, conc) == nil <=>
> > isAssignableTo(conc, iface)
> > ?
> > 
> > Does it warrant a test?
> 
> Yes, there is explicit code in isAssignableTo:
> 
> 	// T is an interface type and x implements T
> 	// (Do this check first as it might succeed early.)
> 	if Ti, ok := Tu.(*Interface); ok {
> 		if m, _ := MissingMethod(x.typ, Ti); m == nil {
> 			return true
> 		}
> 	}

Of course.

[gri, 2013-07-11 21:23:32]

*** Submitted as
https://code.google.com/p/go/source/detail?r=83e9583da735&repo=tools ***

go.tools/go/types: export IsAssignableTo

Tested implictly since its simply calling the
internal isAssignableTo which is used in every
assignment when testing the std library.

R=adonovan
CC=golang-dev
https://codereview.appspot.com/11189043