gqlgen Interface Bug Reproduction

This code reproduces the bug I discussed in 99designs/gqlgen#42

To reproduce:

• Put this in your $GOPATH:
  • git clone https://github.com/ereyes01/gqlgen-interface-bug.git $GOPATH/src/github.com/ereyes01/gqlgen-interface-bug
• Install dependencies:
  • go get github.com/gorilla/websocket
  • go get github.com/vektah/gqlgen
• Generate the graphql code:
  • cd $GOPATH/src/github.com/ereyes01/gqlgen-interface-bug/shapes && gqlgen -out generated.go -package shapes -typemap types.json schema.graphql
• Try to build the playground server:
  • go install github.com/ereyes01/gqlgen-interface-bug/shapes/server

The last command will fail with the following:

# github.com/ereyes01/gqlgen-interface-bug/shapes
shapes/generated.go:711:2: impossible type switch case: *obj (type Shape) cannot have dynamic type Circle (Area method has pointer receiver)
shapes/generated.go:716:2: impossible type switch case: *obj (type Shape) cannot have dynamic type Rectangle (Area method has pointer receiver)