bug#66326: 29.1.50; There should be a way to promote warnings to errors

[sbaugh]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Spencer Baugh <sbaugh@janestreet.com>
>> Date: Tue, 03 Oct 2023 14:39:02 -0400
>> 
>> +(defcustom warning-to-error-types nil
>> +  "List of warning types to signal as an error instead.
>> +If any element of this list matches the TYPE argument to `display-warning',
>> +an error is signaled instead of logging a warning.
>    ^^^^^^^^^^^^^^^^^^^^
> Passive voice alert!
>
>>  (defun display-warning (type message &optional level buffer-name)
>>    "Display a warning message, MESSAGE.
>> @@ -263,105 +278,109 @@ display-warning
>>  disable automatic display of the warning or disable the warning
>>  entirely by setting `warning-suppress-types' or
>>  `warning-suppress-log-types' on their behalf."
>> -  (if (not (or after-init-time noninteractive (daemonp)))
>> -      ;; Ensure warnings that happen early in the startup sequence
>> -      ;; are visible when startup completes (bug#20792).
>> -      (delay-warning type message level buffer-name)
>> -    (unless level
>> -      (setq level :warning))
>> -    (unless buffer-name
>> -      (setq buffer-name "*Warnings*"))
>> +  (unless level
>> +    (setq level :warning))
>> +  (unless buffer-name
>> +    (setq buffer-name "*Warnings*"))
>> +  (cond
>> +   ((< (warning-numeric-level level)
>> +       (warning-numeric-level warning-minimum-log-level)))
>> +   ((warning-suppress-p type warning-suppress-log-types))
>> +   ((warning-suppress-p type warning-to-error-types)
>> +    (warning-to-error type message level))
>> +   ((not (or after-init-time noninteractive (daemonp)))
>> +    ;; Ensure warnings that happen early in the startup sequence
>> +    ;; are visible when startup completes (bug#20792).
>> +    (delay-warning type message level buffer-name))
>> +   (t
>
> AFAICT, this reorders parts of the evaluation, and thus changes the
> semantics/behavior.  Please try to keep the order of the evaluation
> the same as it was, to avoid unintended consequences.  (It will also
> make the patch review easier.)

Unfortuantely it's not possible to avoid either reordering the
evaluation or duplicating some parts of it.  Because, of course we want
a warning to not become an error if it's listed in
warning-suppress-log-types, and we do want it to become an error even if
it occurs early in the startup sequence.  So the
warning-suppress-log-types check has to happen before the to-error
check, and the to-error check has to happen before the early-startup
check.

But currently the warning-suppress-log-types check is after the
early-startup check.  Reordering them doesn't actually change behavior,
because the early-startup check just delays the warning, so it should be
fine.

I can separate out the reordering change into a separate patch if you
like, then you can see that it should not change behavior.