The error message must contain the name of the package from which the type is taken

[gavr123456789]

For example here I have gdk.Window and gtk4.Window. And I cant understand from this error why it doesn't work.
(You need to guess that you need a window from GDK and not GTK)

I think it should look like this:

required type for self: gtk4.Window
  but expression 'window' is of type: gdk.Window

[beef331]

Devel has --declaredLocs which enables similar behaviour.
Given:

import pixie
type Image = object

var a = Image()
encodeImage(a, ffPng)

The following error is emitted

Error: type mismatch: got <test.Image, pixie.FileFormat>
but expected one of: 
proc encodeImage(image: Image; fileFormat: FileFormat): string [proc declared in /home/jason/.nimble/pkgs/pixie-2.1.0/pixie.nim(55, 6)]
  first type mismatch at position: 1
  required type for image: Image [ref declared in /home/jason/.nimble/pkgs/pixie-2.1.0/pixie/images.nim(9, 3)]
  but expression 'a' is of type: Image [object declared in /tmp/test.nim(2, 6)]

expression: encodeImage(a, ffPng)

[timotheecour]

see also #18389 which further improves --declaredLocs to disambiguate

--declaredLocs (and its improvements eg #18389) seem good enough to close this, feel free to re-open if you disagree or have concrete suggestions