Add org-babel-make-language-alias function.

* lisp/ob-core.el (org-babel-make-language-alias): New function.
* lisp/ob-emacs-lisp.el: Use it.

Previously this was accomplished via org-src-lang-modes, but that is a
poor solution, as it conflates the remapping of language mode names with
the creation of aliases.

lisp/ob-core.el

@@ -3161,6 +3161,26 @@ plus the parameter value."
   (and (member "graphics" (cdr (assq :result-params params)))
        (cdr (assq :file params))))
 
+(defun org-babel-make-language-alias (new old)
+  "Make source blocks of type NEW aliases for those of type OLD.
+
+NEW and OLD should be strings.  This function should be called
+after the babel API for OLD-type source blocks is fully defined.
+
+Callers of this function will probably want to add an entry to
+`org-src-lang-modes' as well."
+  (dolist (fn '("execute" "expand-body" "prep-session"
+		"variable-assignments" "load-session"))
+    (let ((sym (intern-soft (concat "org-babel-" fn ":" old))))
+      (when (and sym (fboundp sym))
+	(defalias (intern (concat "org-babel-" fn ":" new)) sym))))
+  ;; Technically we don't need a `dolist' for just one variable, but
+  ;; we keep it for symmetry/ease of future expansion.
+  (dolist (var '("default-header-args"))
+    (let ((sym (intern-soft (concat "org-babel-" var ":" old))))
+      (when (and sym (boundp sym))
+	(defvaralias (intern (concat "org-babel-" var ":" new)) sym)))))
+
 (provide 'ob-core)
 
 ;; Local variables:

lisp/ob-emacs-lisp.el

@@ -72,6 +72,8 @@
          (org-babel-pick-name (cdr (assoc :rowname-names params))
                               (cdr (assoc :rownames params))))))))
 
+(org-babel-make-language-alias "elisp" "emacs-lisp")
+
 (provide 'ob-emacs-lisp)