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, 31 insertions, 15 deletions

diff --git a/src/data.c b/src/data.c
index 681054ff8cb..ea611ad1abf 100644
--- a/src/data.c
+++ b/src/data.c
@@ -248,7 +248,9 @@ a fixed set of types.  */)
           return XSUBR (object)->max_args == UNEVALLED ? Qspecial_form
                  : SUBR_NATIVE_COMPILEDP (object) ? Qsubr_native_elisp
                  : Qprimitive_function;
-        case PVEC_CLOSURE: return Qcompiled_function;
+        case PVEC_CLOSURE:
+          return CONSP (AREF (object, CLOSURE_CODE))
+                 ? Qinterpreted_function : Qbyte_code_function;
         case PVEC_BUFFER: return Qbuffer;
         case PVEC_CHAR_TABLE: return Qchar_table;
         case PVEC_BOOL_VECTOR: return Qbool_vector;
@@ -518,12 +520,32 @@ DEFUN ("subrp", Fsubrp, Ssubrp, 1, 1, 0,
   return Qnil;
 }
 
+DEFUN ("closurep", Fclosurep, Sclosurep,
+       1, 1, 0,
+       doc: /* Return t if OBJECT is a function of type `closure'.  */)
+  (Lisp_Object object)
+{
+  if (CLOSUREP (object))
+    return Qt;
+  return Qnil;
+}
+
 DEFUN ("byte-code-function-p", Fbyte_code_function_p, Sbyte_code_function_p,
        1, 1, 0,
        doc: /* Return t if OBJECT is a byte-compiled function object.  */)
   (Lisp_Object object)
 {
-  if (CLOSUREP (object))
+  if (CLOSUREP (object) && STRINGP (AREF (object, CLOSURE_CODE)))
+    return Qt;
+  return Qnil;
+}
+
+DEFUN ("interpreted-function-p", Finterpreted_function_p,
+       Sinterpreted_function_p, 1, 1, 0,
+       doc: /* Return t if OBJECT is a function of type `interpreted-function'.  */)
+  (Lisp_Object object)
+{
+  if (CLOSUREP (object) && CONSP (AREF (object, CLOSURE_CODE)))
     return Qt;
   return Qnil;
 }
@@ -1174,17 +1196,11 @@ Value, if non-nil, is a list (interactive SPEC).  */)
   else if (CONSP (fun))
     {
       Lisp_Object funcar = XCAR (fun);
-      if (EQ (funcar, Qclosure)
-          || EQ (funcar, Qlambda))
+      if (EQ (funcar, Qlambda))
         {
           Lisp_Object form = Fcdr (XCDR (fun));
-          if (EQ (funcar, Qclosure))
-            form = Fcdr (form);
           Lisp_Object spec = Fassq (Qinteractive, form);
-          if (NILP (spec) && VALID_DOCSTRING_P (CAR_SAFE (form)))
-            /* A "docstring" is a sign that we may have an OClosure.  */
-            genfun = true;
-          else if (NILP (Fcdr (Fcdr (spec))))
+          if (NILP (Fcdr (Fcdr (spec))))
             return spec;
           else
             return list2 (Qinteractive, Fcar (Fcdr (spec)));
@@ -1257,12 +1273,9 @@ The value, if non-nil, is a list of mode name symbols.  */)
   else if (CONSP (fun))
     {
       Lisp_Object funcar = XCAR (fun);
-      if (EQ (funcar, Qclosure)
-          || EQ (funcar, Qlambda))
+      if (EQ (funcar, Qlambda))
         {
           Lisp_Object form = Fcdr (XCDR (fun));
-          if (EQ (funcar, Qclosure))
-            form = Fcdr (form);
           return Fcdr (Fcdr (Fassq (Qinteractive, form)));
         }
     }
@@ -4224,7 +4237,8 @@ syms_of_data (void)
   DEFSYM (Qspecial_form, "special-form");
   DEFSYM (Qprimitive_function, "primitive-function");
   DEFSYM (Qsubr_native_elisp, "subr-native-elisp");
-  DEFSYM (Qcompiled_function, "compiled-function");
+  DEFSYM (Qbyte_code_function, "byte-code-function");
+  DEFSYM (Qinterpreted_function, "interpreted-function");
   DEFSYM (Qbuffer, "buffer");
   DEFSYM (Qframe, "frame");
   DEFSYM (Qvector, "vector");
@@ -4289,6 +4303,8 @@ syms_of_data (void)
   defsubr (&Smarkerp);
   defsubr (&Ssubrp);
   defsubr (&Sbyte_code_function_p);
+  defsubr (&Sinterpreted_function_p);
+  defsubr (&Sclosurep);
   defsubr (&Smodule_function_p);
   defsubr (&Schar_or_string_p);
   defsubr (&Sthreadp);