bug#30039: 26.0.90; [26.1] Making my code warning free is impossible with when-let

[Noam Postavsky <npostavs@users.sourceforge.net>]

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On Tue, Jan 9, 2018 at 3:16 AM, Nicolas Petton <nicolas@petton.fr> wrote:

>> - un-deprecate when-let (and if-let) in Emacs 26 and re-deprecate it
>>   later.
>
> I'm facing the same issue, un-deprecating when-let would also make my CI
> happier.

How about adding a variable which suppresses deprecation warnings from
a specified version and up. Attached is a work-in-progress patch which
would allow you to set byte-compile-not-obsolete-since to "25.1" in
your CI script (or file-locally) and thus ignore deprecation warnings
from 26.1 or newer.

Alternatively, or additionally, we could let
`byte-compile-not-obsolete-funcs' apply to macros as well (currently
macroexp-macroexpand doesn't consult it).

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From 4920c1a8e967b8317a3272feb6bf63b99301be2a Mon Sep 17 00:00:00 2001
From: Noam Postavsky <npostavs@gmail.com>
Date: Wed, 10 Jan 2018 14:07:27 -0500
Subject: [PATCH v1] [WIP] Allow suppressing obsoletion warnings per-version
 (Bug#30039)

* lisp/emacs-lisp/bytecomp.el (byte-compile-not-obsolete-since): New
variable.
(byte-compile-warn-obsolete):
* lisp/emacs-lisp/macroexp.el (macroexp-macroexpand): Check it.

TODO: NEWS, test, other FIXMEs in source.
---
 lisp/emacs-lisp/bytecomp.el | 18 +++++++++++++++---
 lisp/emacs-lisp/macroexp.el | 20 ++++++++++++++------
 2 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/lisp/emacs-lisp/bytecomp.el b/lisp/emacs-lisp/bytecomp.el
index acba9e2..f6ea25b 100644
--- a/lisp/emacs-lisp/bytecomp.el
+++ b/lisp/emacs-lisp/bytecomp.el
@@ -392,6 +392,14 @@ byte-compile-global-not-obsolete-vars
 (defvar byte-compile-not-obsolete-funcs nil
   "List of functions that shouldn't be reported as obsolete.")
 
+(defvar byte-compile-not-obsolete-since nil
+  ;; FIXME: shorter summary line
+  "If set, only report obsolete symbols that were obsoleted
+  earlier than this version.")
+
+;;;###autoload
+(put 'byte-compile-not-obsolete-since 'safe-local-variable #'stringp)
+
 (defcustom byte-compile-generate-call-tree nil
   "Non-nil means collect call-graph information when compiling.
 This records which functions were called and from where.
@@ -1243,12 +1251,16 @@ byte-compile-warn-obsolete
   "Warn that SYMBOL (a variable or function) is obsolete."
   (when (byte-compile-warning-enabled-p 'obsolete)
     (let* ((funcp (get symbol 'byte-obsolete-info))
+           (var-info (get symbol 'byte-obsolete-variable))
            (msg (macroexp--obsolete-warning
                  symbol
-                 (or funcp (get symbol 'byte-obsolete-variable))
+                 (or funcp var-info)
                  (if funcp "function" "variable"))))
-      (unless (and funcp (memq symbol byte-compile-not-obsolete-funcs))
-	(byte-compile-warn "%s" msg)))))
+      (unless (or (and funcp (memq symbol byte-compile-not-obsolete-funcs))
+                  (and (stringp byte-compile-not-obsolete-since)
+                       (version<= byte-compile-not-obsolete-since
+                                  (nth 2 (or funcp var-info)))))
+        (byte-compile-warn "%s" msg)))))
 
 (defun byte-compile-report-error (error-info &optional fill)
   "Report Lisp error in compilation.
diff --git a/lisp/emacs-lisp/macroexp.el b/lisp/emacs-lisp/macroexp.el
index b2ac8be..e64e439 100644
--- a/lisp/emacs-lisp/macroexp.el
+++ b/lisp/emacs-lisp/macroexp.el
@@ -189,12 +189,20 @@ macroexp-macroexpand
                  (byte-compile-warning-enabled-p 'obsolete)))
         (let* ((fun (car form))
                (obsolete (get fun 'byte-obsolete-info)))
-          (macroexp--warn-and-return
-           (macroexp--obsolete-warning
-            fun obsolete
-            (if (symbolp (symbol-function fun))
-                "alias" "macro"))
-           new-form))
+          (unless (or
+                   ;; FIXME: Deduplicate with `byte-compile-warn-obsolete'.
+                   (and fun (memq fun (and (boundp 'byte-compile-not-obsolete-funcs)
+                                           byte-compile-not-obsolete-funcs)))
+                   (and (boundp 'byte-compile-not-obsolete-since)
+                        (stringp byte-compile-not-obsolete-since)
+                        (version< byte-compile-not-obsolete-since
+                                  (nth 2 obsolete))))
+            (macroexp--warn-and-return
+             (macroexp--obsolete-warning
+              fun obsolete
+              (if (symbolp (symbol-function fun))
+                  "alias" "macro"))
+             new-form)))
       new-form)))
 
 (defun macroexp--expand-all (form)
-- 
2.6.2.windows.1