P0987 polymorphic_allocator instead of type-erasure

[wg21bot]

P0987R1 polymorphic_allocator instead of type-erasure (Pablo Halpern)

[wg21bot]

P0987R2 polymorphic_allocator instead of type-erasure (Pablo Halpern)

[AlisdairM]

P0987R2 was applied to the Library Fundamentals 3 TS at the 2022 Kona meeting, so should be closed as done.

[jwakely]

Yes thanks, this was resolved by cplusplus/fundamentals-ts@d74e0e5