go/src/cmd/compile/internal/types2/builtins.go

// builtin type-checks a call to the built-in specified by id and
// reports whether the call is valid, with *x holding the result;
// but x.expr is not set. If the call is invalid, the result is
// false, and *x is undefined.
func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (_ bool) { … }

// hasVarSize reports if the size of type t is variable due to type parameters
// or if the type is infinitely-sized due to a cycle for which the type has not
// yet been checked.
func hasVarSize(t Type, seen map[*Named]bool) (varSized bool) { … }

// applyTypeFunc applies f to x. If x is a type parameter,
// the result is a type parameter constrained by a new
// interface bound. The type bounds for that interface
// are computed by applying f to each of the type bounds
// of x. If any of these applications of f return nil,
// applyTypeFunc returns nil.
// If x is not a type parameter, the result is f(x).
func (check *Checker) applyTypeFunc(f func(Type) Type, x *operand, id builtinId) Type { … }

// makeSig makes a signature for the given argument and result types.
// Default types are used for untyped arguments, and res may be nil.
func makeSig(res Type, args ...Type) *Signature { … }

// arrayPtrDeref returns A if typ is of the form *A and A is an array;
// otherwise it returns typ.
func arrayPtrDeref(typ Type) Type { … }