Return Structs Linter

Checks functions return structs, not interfaces.

Why

"Accept Interfaces, Return Structs"

The output of this should be considered a warning or notification, not an error because there are some valid reasons to return an interface.

I hadn't used the Go ast/parser libraries yet, so this was an excuse.

One file:

go build
./return-structs example/main.go
#Returned interface found on line 15: UserInterface

Entire project:

find . -name "*.go" -not -path "./vendor/*" | xargs -n1 return-structs