b : A
y : A
t14.lean:12:9: error: unknown identifier 'c'
a : foo.A
x : foo.A
t14.lean:19:9: error: unknown identifier 'c'
t14.lean:23:26: error: invalid 'open/export' command option, mixing explicit and implicit 'open/export' options
a : A
c : A
A : Type
a * c : A