(cl-type-of): New function to return more precise types (bug#69739)

* src/data.c (Fcl_type_of): New function, extracted from `Ftype_of`.
Make it return more precise types for symbols, integers, and subrs.
(Ftype_of): Use it.
(syms_of_data): Define the corresponding new symbols and defsubr
the new function.

* doc/lispref/objects.texi (Type Predicates): Document it.

* src/comp.c (emit_limple_insn): Use `Fcl_type_of`.

* lisp/emacs-lisp/cl-preloaded.el (subr): Demote it to `atom`.
(subr-native-elisp, subr-primitive): Add `compiled-function` as
parent instead.
(special-form): New type.

* lisp/obsolete/eieio-core.el (cl--generic-struct-tag):
* lisp/emacs-lisp/cl-generic.el (cl--generic-typeof-generalizer):
Use `cl-type-of`.
cl--generic--unreachable-types): Update accordingly.

test/src/data-tests.el (data-tests--cl-type-of): New test.

1 files changed, 21 insertions, 0 deletions

diff --git a/doc/lispref/objects.texi b/doc/lispref/objects.texi
index 279f449a994..1e448b64296 100644
--- a/doc/lispref/objects.texi
+++ b/doc/lispref/objects.texi
@@ -2207,6 +2207,27 @@ slot is returned; @ref{Records}.
 @end example
 @end defun
 
+@defun cl-type-of object
+This function returns a symbol naming @emph{the} type of
+@var{object}.  It usually behaves like @code{type-of}, except
+that it guarantees to return the most precise type possible, which also
+implies that the specific type it returns may change depending on the
+Emacs version.  For this reason, as a rule you should never compare its
+return value against some fixed set of types.
+
+@example
+(cl-type-of 1)
+     @result{} fixnum
+@group
+(cl-type-of 'nil)
+     @result{} null
+(cl-type-of (record 'foo))
+     @result{} foo
+@end group
+@end example
+@end defun
+
+
 @node Equality Predicates
 @section Equality Predicates
 @cindex equality