commit a27fdba2771b0ff59adfc5ea08ce9eac8387fc01
author Muir Manders <muir@mnd.rs> Sat Dec 07 22:07:30 2019 -0800
committer Rebecca Stambler <rstambler@golang.org> Wed Dec 11 21:44:05 2019 +0000
tree 09bc0527f66a9bb9ed17cca890e29854b066d3e8
parent 37853707689e0142fc480432108355863a222ffd

internal/lsp: check all package variants in find-implementations

We previously only searched for implementations of the object we found
in the "widest" package variant. We instead need to search all
variants because each variant is type checked separately, and
implementations can be located in packages associated with different
variants.

For example, say you have:

-- foo/foo.go --
package foo
type Foo int
type Fooer interface { Foo() Foo }

-- foo/foo_test.go --
package foo
func TestFoo(t *testing.T) {}

-- bar/bar.go --
package bar
import "foo"
type impl struct {}
func (impl) Foo() foo.Foo { return 0 }

When you run find-implementations on the Fooer interface, we
previously would start from the (widest) foo.test's Fooer named
type. Unfortunately bar imports foo, not foo.test, so bar.impl
does not implement foo.test.Fooer. The specific reason is that
bar.impl.Foo returns foo.Foo, whereas foo.test.Fooer.Foo returns
foo.test.Foo, which are distinct *types.Named objects.

Starting our search instead from foo.Fooer resolves this issue.
However, we also need to search from foo.test.Fooer so we match any
implementations in foo_test.go.

Change-Id: I0b0039c98925410751c8f643c8ebd185340e409f
Reviewed-on: https://go-review.googlesource.com/c/tools/+/210459
Run-TryBot: Muir Manders <muir@mnd.rs>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>