Use a dedicated type to represent interpreted-function valuesscratch/interpreted-function

Change `function` so that when evaluating #'(lambda ...)
we return an object of type `interpreted-function` rather than
a list starting with one of `lambda` or `closure`.
The new type reuses the existing PVEC_CLOSURE (nee PVEC_COMPILED)
tag and tries to align the corresponding elements:

- the arglist, the docstring, and the interactive-form go in the
  same slots as for byte-code functions.
- the body of the function goes in the slot used for the bytecode string.
- the lexical context goes in the slot used for the constants of
  bytecoded functions.

The first point above means that `help-function-arglist`,
`documentation`, and `interactive-form`s don't need to
distinguish interpreted and bytecode functions any more.

Main benefits of the change:

- We can now reliably distinguish a list from a function value.
- `cl-defmethod` can dispatch on `interactive-function` and `closure`.
  Dispatch on `function` also works now for interpreted functions but still
  won't work for functions represented as lists or as symbols, of course.
- Function values are now self-evaluating.  That was alrready the case
  when byte-compiled, but not when interpreted since
  (eval '(closure ...)) signals a void-function error.
  That also avoids false-positive warnings about "don't quote your lambdas"
  when doing things like `(mapcar ',func ...)`.

* src/eval.c (Fmake_interpreted_closure): New function.
(Ffunction): Use it and change calling convention of
`Vinternal_make_interpreted_closure_function`.
(FUNCTIONP, Fcommandp, eval_sub, funcall_general, funcall_lambda)
(Ffunc_arity, lambda_arity): Simplify.
(funcall_lambda): Adjust to new representation.
(syms_of_eval): `defsubr` the new function.  Remove definition of `Qclosure`.

* lisp/emacs-lisp/cconv.el (cconv-make-interpreted-closure):
Change calling convention and use `make-interpreted-closure`.

* src/data.c (Fcl_type_of): Distinguish `byte-code-function`s from
`interpreted-function`s.
(Fclosurep, finterpreted_function_p): New functions.
(Fbyte_code_function_p): Don't be confused by `interpreted-function`s.
(Finteractive_form, Fcommand_modes): Simplify.
(syms_of_data): Define new type symbols and `defsubr` the two
new functions.

* lisp/emacs-lisp/cl-print.el (cl-print-object) <interpreted-function>:
New method.

* lisp/emacs-lisp/oclosure.el (oclosure): Refine the parent
to be `closure`.
(oclosure--fix-type, oclosure-type): Simplify.
(oclosure--copy, oclosure--get, oclosure--set): Adjust to
new representation.

* src/callint.c (Fcall_interactively): Adjust to new representation.

* src/lread.c (bytecode_from_rev_list):

* lisp/simple.el (function-documentation):
* lisp/help.el (help-function-arglist): Remove the old `closure` case
and adjust the byte-code case so it handles `interpreted-function`s.

* lisp/emacs-lisp/cl-preloaded.el (closure): New type.
(byte-code-function): Add it as a parent.
(interpreted-function): Adjust parent (the type itself was already
added earlier by accident).

* lisp/emacs-lisp/bytecomp.el (byte-compile--reify-function): Adjust to
new representation.
(byte-compile): Use `interpreted-function-p`.

* lisp/emacs-lisp/byte-opt.el (byte-compile-inline-expand): Adjust to
new representation.
(side-effect-free-fns): Add `interpreted-function-p` and `closurep`.

* src/profiler.c (trace_hash, ffunction_equal): Simplify.
* lisp/profiler.el (profiler-function-equal): Simplify.

* lisp/emacs-lisp/nadvice.el (advice--interactive-form-1):
Use `interpreted-function-p`; adjust to new representation; and take
advantage of the fact that function values are now self-evaluating.

* lisp/emacs-lisp/lisp-mode.el (closure):
Remove `lisp-indent-function` property.

* lisp/emacs-lisp/disass.el (disassemble-internal): Adjust to
new representation.
* lisp/emacs-lisp/edebug.el (edebug--strip-instrumentation):
Use `interpreted-function-p`.
* lisp/emacs-lisp/comp-common.el (comp-known-type-specifiers):
Add `closurep` and `interpreted-function-p`.

* test/lisp/help-fns-tests.el (help-fns-test-lisp-defun): Adjust to
more precise type info in `describe-function`.
* test/lisp/erc/resources/erc-d/erc-d-tests.el (erc-d--render-entries):
Use `interpreted-function-p`.
* test/lisp/emacs-lisp/macroexp-resources/vk.el (vk-f4, vk-f5):
Don't hardcode function values.

* doc/lispref/functions.texi (Anonymous Functions): Don't suggest that
function values are lists.  Reword "self-quoting" to reflect the
fact that #' doesn't return the exact same object.  Update examples
with the new shape of the return value.

* doc/lispref/variables.texi (Lexical Binding):
* doc/lispref/lists.texi (Rearrangement):
* doc/lispref/control.texi (Handling Errors): Update examples to reflect
new representation of function values.

1 files changed, 39 insertions, 57 deletions

diff --git a/lisp/emacs-lisp/oclosure.el b/lisp/emacs-lisp/oclosure.el
index 4da8e61aaa7..165d7c4b6e8 100644
--- a/lisp/emacs-lisp/oclosure.el
+++ b/lisp/emacs-lisp/oclosure.el
@@ -146,7 +146,7 @@
 (setf (cl--find-class 'oclosure)
       (oclosure--class-make 'oclosure
                             "The root parent of all OClosure types"
-                            nil (list (cl--find-class 'function))
+                            nil (list (cl--find-class 'closure))
                             '(oclosure)))
 (defun oclosure--p (oclosure)
   (not (not (oclosure-type oclosure))))
@@ -431,75 +431,57 @@ ARGS and BODY are the same as for `lambda'."
 
 (defun oclosure--fix-type (_ignore oclosure)
   "Helper function to implement `oclosure-lambda' via a macro.
-This has 2 uses:
-- For interpreted code, this converts the representation of type information
-  by moving it from the docstring to the environment.
-- For compiled code, this is used as a marker which cconv uses to check that
-  immutable fields are indeed not mutated."
-  (if (byte-code-function-p oclosure)
-      ;; Actually, this should never happen since `cconv.el' should have
-      ;; optimized away the call to this function.
-      oclosure
-    ;; For byte-coded functions, we store the type as a symbol in the docstring
-    ;; slot.  For interpreted functions, there's no specific docstring slot
-    ;; so `Ffunction' turns the symbol into a string.
-    ;; We thus have convert it back into a symbol (via `intern') and then
-    ;; stuff it into the environment part of the closure with a special
-    ;; marker so we can distinguish this entry from actual variables.
-    (cl-assert (eq 'closure (car-safe oclosure)))
-    (let ((typename (nth 3 oclosure))) ;; The "docstring".
-      (cl-assert (stringp typename))
-      (push (cons :type (intern typename))
-            (cadr oclosure))
-      oclosure)))
+This is used as a marker which cconv uses to check that
+immutable fields are indeed not mutated."
+  (cl-assert (closurep oclosure))
+  ;; This should happen only for interpreted closures since `cconv.el'
+  ;; should have optimized away the call to this function.
+  oclosure)
 
 (defun oclosure--copy (oclosure mutlist &rest args)
+  (cl-assert (closurep oclosure))
   (if (byte-code-function-p oclosure)
       (apply #'make-closure oclosure
              (if (null mutlist)
                  args
                (mapcar (lambda (arg) (if (pop mutlist) (list arg) arg)) args)))
-    (cl-assert (eq 'closure (car-safe oclosure))
-               nil "oclosure not closure: %S" oclosure)
-    (cl-assert (eq :type (caar (cadr oclosure))))
-    (let ((env (cadr oclosure)))
-      `(closure
-           (,(car env)
-            ,@(named-let loop ((env (cdr env)) (args args))
-                (when args
-                  (cons (cons (caar env) (car args))
-                        (loop (cdr env) (cdr args)))))
-            ,@(nthcdr (1+ (length args)) env))
-           ,@(nthcdr 2 oclosure)))))
+    (cl-assert (consp (aref oclosure 1)))
+    (cl-assert (null (aref oclosure 3)))
+    (cl-assert (symbolp (aref oclosure 4)))
+    (let ((env (aref oclosure 2)))
+      (make-interpreted-closure
+       (aref oclosure 0)
+       (aref oclosure 1)
+       (named-let loop ((env env) (args args))
+         (if (null args) env
+           (cons (cons (caar env) (car args))
+                 (loop (cdr env) (cdr args)))))
+       (aref oclosure 4)
+       (if (> (length oclosure) 5)
+           `(interactive ,(aref oclosure 5)))))))
 
 (defun oclosure--get (oclosure index mutable)
-  (if (byte-code-function-p oclosure)
-      (let* ((csts (aref oclosure 2))
-             (v (aref csts index)))
-        (if mutable (car v) v))
-    (cl-assert (eq 'closure (car-safe oclosure)))
-    (cl-assert (eq :type (caar (cadr oclosure))))
-    (cdr (nth (1+ index) (cadr oclosure)))))
+  (cl-assert (closurep oclosure))
+  (let* ((csts (aref oclosure 2)))
+    (if (vectorp csts)
+        (let ((v (aref csts index)))
+          (if mutable (car v) v))
+      (cdr (nth index csts)))))
 
 (defun oclosure--set (v oclosure index)
-  (if (byte-code-function-p oclosure)
-      (let* ((csts (aref oclosure 2))
-             (cell (aref csts index)))
-        (setcar cell v))
-    (cl-assert (eq 'closure (car-safe oclosure)))
-    (cl-assert (eq :type (caar (cadr oclosure))))
-    (setcdr (nth (1+ index) (cadr oclosure)) v)))
+  (cl-assert (closurep oclosure))
+  (let ((csts (aref oclosure 2)))
+    (if (vectorp csts)
+        (let ((cell (aref csts index)))
+          (setcar cell v))
+      (setcdr (nth index csts) v))))
 
 (defun oclosure-type (oclosure)
-  "Return the type of OCLOSURE, or nil if the arg is not a OClosure."
-  (if (byte-code-function-p oclosure)
-      (let ((type (and (> (length oclosure) 4) (aref oclosure 4))))
-        (if (symbolp type) type))
-    (and (eq 'closure (car-safe oclosure))
-         (let* ((env (car-safe (cdr oclosure)))
-                (first-var (car-safe env)))
-           (and (eq :type (car-safe first-var))
-                (cdr first-var))))))
+  "Return the type of OCLOSURE, or nil if the arg is not an OClosure."
+  (and (closurep oclosure)
+       (> (length oclosure) 4)
+       (let ((type (aref oclosure 4)))
+         (if (symbolp type) type))))
 
 (defconst oclosure--accessor-prototype
   ;; Use `oclosure--lambda' to circumvent a bootstrapping problem: