commit 5a76f03bc7c327212912ed6b2a76a10d7f39b224
author Muir Manders <muir@mnd.rs> Fri Nov 15 16:14:15 2019 -0800
committer Rebecca Stambler <rstambler@golang.org> Mon Nov 18 05:14:29 2019 +0000
tree 6acf401674d44f63f52a94c886dd46e859424cc7
parent 80313e1ba7181ff88576941b25b4beb004e348db

internal/lsp: fix variadic interface completion ranking

In cases like:

var foo []io.Writer
var buf *bytes.Buffer
foo = append(foo, <>)

we weren't giving "buf" a good score. When comparing the candidate
type *bytes.Buffer to the (variadic) expected type []io.Writer we were
turning the candidate type into []*bytes.Buffer. However, of course,
[]*bytes.Buffer is not assignable to []io.Writer, so the types didn't
match. Now we instead turn the expected type []io.Writer into
io.Writer and compare to *bytes.Buffer.

I fixed the @rank test note to check that the candidates' scores are
strictly decreasing. Previously it would allow candidates with the
same score if they happened to be in the right order. This made it
easier to right a test for this issue, but also uncovered an issue
with untyped completion logic. I fixed it to do the untyped constant
check if _either_ the expected or candidate type is
untyped (previously it required the candidate type to be untyped).

Fixes golang/go#35625.

Change-Id: I9a837d6a781669cb7a2f1d6d3d7f360c85be49eb
Reviewed-on: https://go-review.googlesource.com/c/tools/+/207518
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>