Ada 2012 Reference Manual
13.10 Unchecked Access Value Creation
The attribute Unchecked_Access is used to create access values in an unsafe manner — the programmer is responsible for preventing “dangling references.”
Static Semantics
The following attribute is defined for a prefix X that denotes an aliased view of an object:
X'Unchecked_Access
All rules and semantics that apply to X'Access (see 3.10.2) apply also to X'Unchecked_Access, except that, for the purposes of accessibility rules and checks, it is as if X were declared immediately within a library package.
NOTES
25 This attribute is provided to support the situation where a local object is to be inserted into a global linked data structure, when the programmer knows that it will always be removed from the data structure prior to exiting the object's scope. The Access attribute would be illegal in this case (see 3.10.2, “Operations of Access Types”).
26 There is no Unchecked_Access attribute for subprograms.
