x/tools/gopls: crash in Hover (telemetry)

adonovan commented 2 months ago

#!stacks
"runtime.sigpanic" && "golang.hover:+170"

This stack zUGLQA was reported by telemetry:

if def, ok := pkg.TypesInfo().Defs[ident]; ok && ident.Pos() == def.Pos() {

Looks like Defs[ident]=nil is an actual map entry.

golang.org/x/tools/gopls@v0.16.1 go1.23.0 darwin/amd64 vscode (1)

Issue created by golang.org/x/tools/gopls/internal/telemetry/cmd/stacks.

gabyhelp commented 2 months ago

Related Issues and Documentation

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adonovan commented 2 months ago

I can't explain this one. The only three calls to recordDef(id, nil) in the type checker are for:

package id
switch id := expr.(type) {}
the blank identifier in _ = expr.

It can't be (1) because the Hover logic handled the package clause specially at L186. It can't be (2) because this would cause referencedObject to return a non-nil third result (selectedType), causing an early return. And it can't be (3) because that would cause referencedObject not to return a non-nil Object, Ident pair, leading to an early return.

Clearly there is a mistake in my logic. But where?

findleyr commented 1 month ago

Agreed. I think the best we'll be able to do here is downgrade the panic into two or more bug reports that refine the panic.

This is not the first "can't happen" bug related to go/types...

gopherbot commented 6 hours ago

Change https://go.dev/cl/627015 mentions this issue: gopls/internal/golang: refine crash report golang/go#69362

golang / go

x/tools/gopls: crash in Hover (telemetry) #69362