Related Issues

• panic: reflect.Value.Convert: value of type unsafe.Pointer cannot be converted to #33610 (closed)
• reflect: Convert to unsafe.Pointer doesn't work #8964 (closed)
• reflect: Value.IsNil panics for UnsafePointer #29381 (closed)
• playground: "cannot use unsafe.Pointer" error when using reflect.ValueOf #5578 (closed)

Related Code Changes

• reflect: allow conversion to and from unsafe.Pointer

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

reflect.ValueOf(&m).UnsafePointer()

Unlike many projects, the Go project does not use GitHub Issues for general discussion or asking questions. GitHub Issues are used for tracking bugs and proposals only.

For questions please refer to https://github.com/golang/go/wiki/Questions

I'm aware there's other ways to do this, I'm opening an issue because doing things this way exposes an edge case that produces unusable pointers.

You can do:

	var m map[string]any
	*(*unsafe.Pointer)(unsafe.Pointer(&m)) = uPtr

I agree that the interaction of unsafe and reflect isn't great. But then again, if you're using unsafe you don't normally need reflect.

if you're using unsafe you don't normally need reflect.

Glad you bring that up - the pointer returned by reflect.ValueOf(m).UnsafePointer() is the actual map reference, which would be equivalent to unsafe.Pointer(m), but that's not valid, only unsafe.Pointer(&m) is. That's why I mentioned that perhaps the unsafe pkg should have special methods for maps.

I think we would need a very good reason to add anything map-specific to the unsafe package, more than just symmetry or cleanliness. That said, if you want to pursue this, file a proposal issue. See https://go.dev/s/proposal. Thanks.