ForPackage computes which generic features are used directly by the package being analyzed.

EmbeddedTypeSets indicates whether the package declares interfaces that contain structural type restrictions, i.e.

FuncInstantiation indicates whether the package instantiates any generic functions.

GenericFuncDecls indicates whether the package declares functions with type parameters.

GenericTypeDecls indicates whether the package declares types with type parameters.

TypeInstantiation indicates whether the package instantiates any generic types.

Features is a set of flags reporting which features of generic Go code a package uses, or 0.