x/tools/gopls: panic in internal/lsp/source.pathLinkAndSymbolName

[danp]

What version of Go are you using (go version)?

$ go version
go version devel +c4fed25553 Mon Jul 27 18:24:32 2020 +0000 darwin/amd64

Using gopls built from golang/tools@df70183

What operating system and processor architecture are you using (go env)?

macOS, Emacs 26.3, lsp-mode 20200726.1814

What did you do?

Moved my cursor over the method name in a method declaration, such as Bar in:

func (f *foo) Bar(ctx context.Context, req *api.BarRequest) (*api.BarResponse, error) {

What did you expect to see?

Nothing, or maybe an info hover.

What did you see instead?

panic: interface conversion: types.Type is nil, not *types.Named

goroutine 14963 [running]:
golang.org/x/tools/internal/lsp/source.pathLinkAndSymbolName(0xc01a362360, 0xc00fc8bbd0, 0xc00e73c1e0, 0xc000c9d500, 0x6b, 0xc00f49e201, 0x1)
	/Users/dan.peterson/Projects/go/src/golang.org/x/tools/internal/lsp/source/hover.go:169 +0xe18
golang.org/x/tools/internal/lsp/source.HoverIdentifier(0x1ab0460, 0xc00e72a420, 0xc01a362360, 0x0, 0x0, 0x0)
	/Users/dan.peterson/Projects/go/src/golang.org/x/tools/internal/lsp/source/hover.go:112 +0x272
golang.org/x/tools/internal/lsp/source.Hover(0x1ab03a0, 0xc00f1ccac0, 0x1ac06c0, 0xc017436a20, 0x1ab3fe0, 0xc018733260, 0x4075600000000000, 0x403c000000000000, 0x1ab3fe0, 0xc018733260, ...)
	/Users/dan.peterson/Projects/go/src/golang.org/x/tools/internal/lsp/source/hover.go:56 +0xe5
golang.org/x/tools/internal/lsp.(*Server).hover(0xc0003382d0, 0x1ab03a0, 0xc00f1ccac0, 0xc00e72a030, 0x0, 0x0, 0xc001dca420)
	/Users/dan.peterson/Projects/go/src/golang.org/x/tools/internal/lsp/hover.go:24 +0x216
golang.org/x/tools/internal/lsp.(*Server).Hover(0xc0003382d0, 0x1ab03a0, 0xc00f1ccac0, 0xc00e72a030, 0xc00e72a030, 0x0, 0x0)
	/Users/dan.peterson/Projects/go/src/golang.org/x/tools/internal/lsp/server_gen.go:96 +0x49
golang.org/x/tools/internal/lsp/protocol.serverDispatch(0x1ab03a0, 0xc00f1ccac0, 0x1ac3c40, 0xc0003382d0, 0xc00e72a000, 0x1ab05e0, 0xc00f1cc900, 0x1a9dce0, 0xc001dca000, 0x1ab0460)
	/Users/dan.peterson/Projects/go/src/golang.org/x/tools/internal/lsp/protocol/tsserver.go:269 +0x16b2
golang.org/x/tools/internal/lsp/protocol.ServerHandler.func1(0x1ab03a0, 0xc00f1ccac0, 0xc00e72a000, 0x1ab05e0, 0xc00f1cc900, 0x1f00960, 0x1aae760)
	/Users/dan.peterson/Projects/go/src/golang.org/x/tools/internal/lsp/protocol/protocol.go:62 +0xc5
golang.org/x/tools/internal/lsp/lsprpc.handshaker.func1(0x1ab03a0, 0xc00f1ccac0, 0xc00e72a000, 0x1ab05e0, 0xc00f1cc900, 0x0, 0x0)
	/Users/dan.peterson/Projects/go/src/golang.org/x/tools/internal/lsp/lsprpc/lsprpc.go:521 +0x432
golang.org/x/tools/internal/jsonrpc2.MustReplyHandler.func1(0x1ab03a0, 0xc00f1ccac0, 0xc00e5f2c00, 0x1ab05e0, 0xc00f1cc900, 0x0, 0x10000c000746f60)
	/Users/dan.peterson/Projects/go/src/golang.org/x/tools/internal/jsonrpc2/handler.go:35 +0xcf
golang.org/x/tools/internal/jsonrpc2.AsyncHandler.func1.2(0xc00c4f16e0, 0xc00e4fdce0, 0xc000334e10, 0x1ab03a0, 0xc00f1ccac0, 0xc00e5f2c00, 0x1ab05e0, 0xc00f1cc900)
	/Users/dan.peterson/Projects/go/src/golang.org/x/tools/internal/jsonrpc2/handler.go:103 +0x86
created by golang.org/x/tools/internal/jsonrpc2.AsyncHandler.func1
	/Users/dan.peterson/Projects/go/src/golang.org/x/tools/internal/jsonrpc2/handler.go:100 +0x173

Process gopls stderr<1> finished

[danp]

Maybe a dup of or related to #40464?

[stamblerre]

Yep I think so. Should be fixed in the latest pre-release (gopls/v0.4.4-pre2).

[danp]

Just to double check: this is happening at golang/tools@df70183, which if I understand correctly includes everything v0.4.4-pre2 does. I did just try again after explicitly checking out gopls/v0.4.4-pre2 and I'm still getting the same panic.

[stamblerre]

Oh no, I didn't realize it was still happening. This is proving quite tricky to track down - I'll keep looking.

[gopherbot]

Change https://golang.org/cl/245486 mentions this issue: internal/lsp: avoid nil interface bug in searchForEnclosing

[gopherbot]

Change https://golang.org/cl/245538 mentions this issue: [gopls-release-branch.0.4] internal/lsp: properly check for nil on i.enclosing