Structural Generic Instantiation (GNAT Reference Manual)

#### 17.3.14 Structural Generic Instantiation ¶

The compiler implements a second kind of generic instantiation, called “structural”, alongside the traditional instantiation specified by the language, which is defined as follows: the structural instantiation of a generic unit on given actual parameters is the anonymous instantiation of the generic unit on the actual parameters done in the outermost scope where it would be legal to do an identical traditional instantiation.

There is at most one structural instantiation of a generic unit on given actual parameters done in a partition.

Structural generic instances (the product of structural instantiation) are implicitly created whenever a reference to them is made in a place where a name is accepted by the language.