cl-preloaded.el: Fix the type lattice

We generally want types to form not just a DAG but a lattice.
If objects can be both `keyword` and `symbol-with-pos`, this
means there should be a more precise type describing this intersection.
If we ever find the need for such a refinement, we could add
such a `keyword-with-pos` type, but here I took the simpler
route of treating `keyword` not as a proper built-in type but
as a second-class type like `natnum`.

While fixing this problem, also fix the problem we had where
`functionp` was not quite adequate to characterize objects of type
`function`, by introducing a new predicate `cl-functionp` for that.

* lisp/emacs-lisp/cl-preloaded.el (cl-functionp): New function.
(function): Use it.
(keyword): Don't declare it as a built-in type.
(user-ptrp): Remove redundant declaration.

* lisp/emacs-lisp/cl-generic.el (cl--generic--unreachable-types):
Delete constant.
(cl-generic-generalizers): Remove corresponding test.

* lisp/emacs-lisp/cl-macs.el (cl-deftype-satisfies): Add entry for
`keyword` type.

* lisp/emacs-lisp/comp.el (comp-known-predicates): Fix type for
negative result of `characterp`.  Remove duplicate `numberp` entry.
Fix types for `keywordp` now that `keyword` is not a built-in type any more.

* test/src/data-tests.el (data-tests--cl-type-of): Add a few cases.
Remove workaround for `function`.

1 files changed, 3 insertions, 3 deletions

diff --git a/lisp/emacs-lisp/comp.el b/lisp/emacs-lisp/comp.el
index 9976a58f893..2544be85bb2 100644
--- a/lisp/emacs-lisp/comp.el
+++ b/lisp/emacs-lisp/comp.el
@@ -193,13 +193,14 @@ Useful to hook into pass checkers.")
 ;; cl-macs.el. We can't use `cl-deftype-satisfies' directly as the
 ;; relation type <-> predicate is not bijective (bug#45576).
 (defconst comp-known-predicates
+  ;; FIXME: Auto-generate (most of) it from `cl-deftype-satifies'?
   '((arrayp              array)
     (atom		 atom)
     (bool-vector-p       bool-vector)
     (booleanp            boolean)
     (bufferp             buffer)
     (char-table-p	 char-table)
-    (characterp          fixnum)
+    (characterp          fixnum t)
     (consp               cons)
     (floatp              float)
     (framep              frame)
@@ -207,14 +208,13 @@ Useful to hook into pass checkers.")
     (hash-table-p	 hash-table)
     (integer-or-marker-p integer-or-marker)
     (integerp            integer)
-    (keywordp            keyword)
+    (keywordp            symbol t)
     (listp               list)
     (markerp             marker)
     (natnump             (integer 0 *))
     (null		 null)
     (number-or-marker-p  number-or-marker)
     (numberp             number)
-    (numberp             number)
     (obarrayp            obarray)
     (overlayp            overlay)
     (processp            process)