Define if-let* and derivatives as aliases for if-let etc

This commit reverts declaring `if-let' and `when-let' obsolete in
favor of the new `if-let*' and `when-let*' versions because of the
compiler warning mess (Bug#30039).  Instead we make foo-let* aliases
for foo-let.  The old single-tuple variable spec case is still
supported for backward compatibility.
* lisp/emacs-lisp/subr-x.el (if-let, when-let): Don't declare
obsolete.  Tweak edebug specs.
(and-let): Renamed from `and-let*' for compatibility with the names
`if-let' and `when-let'.
(if-let*, when-let*, and-let*): Define as aliases for `if-let',
`when-let' and `and-let'.
* test/lisp/emacs-lisp/subr-x-tests.el (if-let-single-tuple-case-test)
(when-let-single-tuple-case-test): New tests for the single-binding
tuple case.
In the whole file, prefer the names without "*".

1 files changed, 23 insertions, 32 deletions

diff --git a/lisp/emacs-lisp/subr-x.el b/lisp/emacs-lisp/subr-x.el
index 21dba377bf1..b2d7f0dec4f 100644
--- a/lisp/emacs-lisp/subr-x.el
+++ b/lisp/emacs-lisp/subr-x.el
@@ -121,7 +121,7 @@ If ELT is of the form ((EXPR)), listify (EXPR) with a dummy symbol."
                 binding))
             bindings)))
 
-(defmacro if-let* (varlist then &rest else)
+(defmacro if-let (varlist then &rest else)
   "Bind variables according to VARLIST and eval THEN or ELSE.
 Each binding is evaluated in turn, and evaluation stops if a
 binding value is nil.  If all are non-nil, the value of THEN is
@@ -131,10 +131,18 @@ Each element of VARLIST is a list (SYMBOL VALUEFORM) which binds
 SYMBOL to the value of VALUEFORM.  An element can additionally
 be of the form (VALUEFORM), which is evaluated and checked for
 nil; i.e. SYMBOL can be omitted if only the test result is of
-interest."
+interest.
+
+As a special case, a VARLIST of the form (SYMBOL SOMETHING) is
+treated like ((SYMBOL SOMETHING))."
   (declare (indent 2)
-           (debug ((&rest [&or symbolp (symbolp form) (form)])
+           (debug ([&or (symbolp form)
+                        (&rest [&or symbolp (symbolp form) (form)])]
                    form body)))
+  (pcase varlist
+    (`(,(pred symbolp) ,_)
+     ;; the single-tuple syntax case, for backward compatibility
+     (cl-callf list varlist)))
   (if varlist
       `(let* ,(setq varlist (internal--build-bindings varlist))
          (if ,(caar (last varlist))
@@ -142,23 +150,23 @@ interest."
            ,@else))
     `(let* () ,then)))
 
-(defmacro when-let* (varlist &rest body)
+(defmacro when-let (varlist &rest body)
   "Bind variables according to VARLIST and conditionally eval BODY.
 Each binding is evaluated in turn, and evaluation stops if a
 binding value is nil.  If all are non-nil, the value of the last
 form in BODY is returned.
 
-VARLIST is the same as in `if-let*'."
-  (declare (indent 1) (debug if-let*))
-  (list 'if-let* varlist (macroexp-progn body)))
+VARLIST is the same as in `if-let'."
+  (declare (indent 1) (debug ([&or (symbolp form)
+                                   (&rest [&or symbolp (symbolp form) (form)])]
+                              body)))
+  (list 'if-let varlist (macroexp-progn body)))
 
-(defmacro and-let* (varlist &rest body)
+(defmacro and-let (varlist &rest body)
   "Bind variables according to VARLIST and conditionally eval BODY.
-Like `when-let*', except if BODY is empty and all the bindings
+Like `when-let', except if BODY is empty and all the bindings
 are non-nil, then the result is non-nil."
-  (declare (indent 1)
-           (debug ((&rest [&or symbolp (symbolp form) (form)])
-                   body)))
+  (declare (indent 1) (debug when-let))
   (let (res)
     (if varlist
         `(let* ,(setq varlist (internal--build-bindings varlist))
@@ -166,26 +174,9 @@ are non-nil, then the result is non-nil."
                ,@(or body `(,res))))
       `(let* () ,@(or body '(t))))))
 
-(defmacro if-let (spec then &rest else)
-  "Bind variables according to SPEC and eval THEN or ELSE.
-Like `if-let*' except SPEC can have the form (SYMBOL VALUEFORM)."
-  (declare (indent 2)
-           (debug ([&or (&rest [&or symbolp (symbolp form) (form)])
-                        (symbolp form)]
-                   form body))
-           (obsolete "use `if-let*' instead." "26.1"))
-  (when (and (<= (length spec) 2)
-             (not (listp (car spec))))
-    ;; Adjust the single binding case
-    (setq spec (list spec)))
-  (list 'if-let* spec then (macroexp-progn else)))
-
-(defmacro when-let (spec &rest body)
-  "Bind variables according to SPEC and conditionally eval BODY.
-Like `when-let*' except SPEC can have the form (SYMBOL VALUEFORM)."
-  (declare (indent 1) (debug if-let)
-           (obsolete "use `when-let*' instead." "26.1"))
-  (list 'if-let spec (macroexp-progn body)))
+(defalias 'if-let*   #'if-let)
+(defalias 'when-let* #'when-let)
+(defalias 'and-let*  #'and-let)
 
 (defsubst hash-table-empty-p (hash-table)
   "Check whether HASH-TABLE is empty (has 0 elements)."