Comment 1:

Probably not important for Go 1.

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

Comment 2:

This issue was closed by revision 8b7cdb7.

Status changed to Fixed.

Comment 3:

I just built this revision, and it looks like the problem has just changed which
comments are moved?  I think the proper fix should be: don't move comments to the other
side of commas.
My examples:
        var _ = []int{/* 1 */ x, /* 2 */ y}   /* comments in front of list elements */
        var _ = []int{x /* 1 */, y /* 2 */ }  /* comments after list elements */
Running through gofmt produces:
        var _ = []int{ /* 1 */ x /* 2 */, y}  /* comments in front of list elements */
        var _ = []int{x /* 1 */, y /* 2 */}   /* comments after list elements */
Previously, the second line was broken as the /* 1 */ comment would be moved to the
right of the comma next to the y, so the 'y' had two comments associated with it.
With the new code, we've instead broken the first case where the comments precede the
list elements.  The /* 2 */ on the first line has now moved to the left of the comma so
now the 'x' has two comments associated with it.

Comment 4:

/* comments in front of list elements */
don't do that anymore.

Comment 5:

There is no position information for commas recorded in the AST. As a result, their
position has to be estimated. It appears to be a more common style to put a comment
after a list entry than before; the new heuristic takes that into account. The existing
code base supports this assumptions and the fix improved comment placement for several
packages with such comments.
One could selectively store comma position information where needed, but that effort
(code and space consumption) seems not justified given that the new heuristic appears to
work reasonably well (and the case of comments in comma-separated lists is rare, anyway).

Comment 6:

Why not do the following: When there is at least one comment in a comma separated list,
and it is not where you expect it, insert a known phantom comment in each uncommented
position. On output, drop the phantom comments. (string address== phantom string)