runtime: SetFinalizer may be called on local objects, contra doc

[adonovan]

Fro http://golang.org/pkg/runtime/#SetFinalizer:
"The argument x must be a pointer to an object allocated by calling new or by
taking the address of a composite literal. The argument f must be a function that takes
a single argument of x's type and can have arbitrary ignored return values. If either of
these is not true, SetFinalizer aborts the program."

SetFinalizer does not, in fact, abort the program if the argument x is a the address of
a local object.  I think the spec wording needs to be updated to reflect this.

http://play.golang.org/p/v8810GsAzF

[ianlancetaylor]

Comment 1:

I wouldn't call this the spec--we usually use that word for the language spec.  This is
just the documentation.
It is of course unsurprising that SetFinalizer works if you take the address of a local
variable.  I agree that the docs should be updated though I think the update can be a
minor one.

Labels changed: added priority-later, documentation, removed priority-triage.

[rsc]

Comment 2:

Labels changed: added go1.3maybe.

[rsc]

Comment 3:

Labels changed: added release-none, removed go1.3maybe.

[rsc]

Comment 4:

Labels changed: added repo-main.

[gopherbot]

CL https://golang.org/cl/29592 mentions this issue.