+ (let ((layout (info :type :compiler-layout name)))
+ (cond (layout
+ ;; ordinary case: When the DEFSTRUCT is at top level,
+ ;; then EVAL-WHEN (COMPILE) stuff will have set up the
+ ;; layout for us to use.
+ (unless (typep (layout-info layout) 'defstruct-description)
+ (error "Class is not a structure class: ~S" name))
+ `,layout)
+ (t
+ ;; KLUDGE: In the case that DEFSTRUCT is not at top-level
+ ;; the layout doesn't exist at compile time. In that case
+ ;; we laboriously look it up at run time. This code will
+ ;; run on every constructor call and will likely be quite
+ ;; slow, so if anyone cares about performance of
+ ;; non-toplevel DEFSTRUCTs, it should be rewritten to be
+ ;; cleverer. -- WHN 2002-10-23
+ (sb!c::compiler-note
+ "implementation limitation: ~
+ Non-toplevel DEFSTRUCT constructors are slow.")
+ (with-unique-names (layout)
+ `(let ((,layout (info :type :compiler-layout ',name)))
+ (unless (typep (layout-info ,layout) 'defstruct-description)
+ (error "Class is not a structure class: ~S" ',name))
+ ,layout))))))