5d553d6369
This PR fixes a stack overflow caused by a cyclic assignment in the metavariable context. The cycle is unintentionally introduced by the structure instance elaborator. closes #3150
24 lines
541 B
Text
24 lines
541 B
Text
class One (α : Type) where
|
||
one : α
|
||
|
||
variable (R A : Type) [One R] [One A]
|
||
|
||
class OneHom where
|
||
toFun : R → A
|
||
map_one : toFun One.one = One.one
|
||
|
||
structure Subone where
|
||
mem : R → Prop
|
||
one_mem : mem One.one
|
||
|
||
structure Subalgebra [OneHom R A] extends Subone A : Type where
|
||
algebraMap_mem : ∀ r : R, mem (OneHom.toFun r)
|
||
one_mem := OneHom.map_one (R := R) (A := A) ▸ algebraMap_mem One.one
|
||
|
||
/--
|
||
error: fields missing: 'one_mem'
|
||
-/
|
||
#guard_msgs in
|
||
example [OneHom R A] : Subalgebra R A where
|
||
mem := _
|
||
algebraMap_mem := _
|