33 Execution control library [exec]

33.5 Queries [exec.queries]

33.5.4 execution​::​get_env [exec.get.env]

execution​::​get_env is a customization point object.
For a subexpression o, execution​::​get_env(o) is expression-equivalent to:
The value of get_env(o) shall be valid while o is valid.
[Note 1: 
When passed a sender object, get_env returns the sender's associated attributes.
When passed a receiver, get_env returns the receiver's associated execution environment.
— end note]