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Subject: Re: [PHP-DEV] Re: Inconsistency in PHP 8.5 deprecation of terminating
 case with semicolon
To: Theodore Brown <theodorejb@outlook.com>,
 PHP internals <internals@lists.php.net>
References: <68EEE5F4.5070105@adviesenzo.nl>
 <BL4P223MB13645C59490A13076481C3A9DEE8A@BL4P223MB1364.NAMP223.PROD.OUTLOOK.COM>
Message-ID: <68EF9D5D.2030806@adviesenzo.nl>
Date: Wed, 15 Oct 2025 15:10:53 +0200
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From: php-internals_nospam@adviesenzo.nl (Juliette Reinders Folmer)

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On 15-10-2025 6:21, Theodore Brown wrote:
> On Tue, October 14 2025 at 18:08 Juliette Reinders Folmer wrote:
>
>> Dear Theodore and list,
>>
>> I've been looking into the "Deprecate semicolon after case in switch statement" PHP 8.5 deprecation [1]
>> with the aim of adding a sniff for this to the PHPCompatibility standard and I'm noticing an oddity for
>> which I would like to clarify whether this is intentional or an oversight.
>>
>> As demonstrated in the example code provided in the deprecation RFC, both switch `case` condition
>> statements, as well as `default` statements, can be ended with a semicolon.
>>
>> So when I first read the RFC, I interpreted the proposal to include both `case` as well as `default`,
>> as, in my mind, `default` is just a special `case` in a switch.
>>
>> However, the RFC explicitly only talked about deprecating the use of a semicolon after a
>> `case` statement and the implementation has followed this to the letter. [2]
>>
>> The net result of this, is that you can now have a `switch` statement with semicolons
>> terminating `case` statements and `default` statements, where the former (`case`) will
>> result in a deprecation notice, while the latter (`default`) will not. For an example, see [3]
>>
>> This feels inconsistent to me and counter to the intention of the RFC, which is stated to be:
>>
>>> Case statements followed by a semicolon can cause confusion, as a developer may think they
>>> behave differently in some way from regular case statements (e.g. preventing fallthrough),
>>> when they do not.
>> Which leaves me wondering what the reason was not to _also_ deprecate the use of a semicolon
>> to terminate a `default` statement in a switch ? I can't find any discussion about this in the
>> original mailing list thread [4].
>>
>> Anyone would care to clarify ?
> Hi Juliette,
>
> Thank you for pointing out the discrepancy. You are correct that `default` is just a special
> case statement, and the intention in the RFC was to output the deprecation message for default cases
> as well (the example in the RFC included a default case followed by a semicolon to highlight this).
>
> The fact that a deprecation message isn't shown for default cases is an oversight on my part
> when I implemented the RFC. The merged implementation correctly updated the AST for default
> case statements followed by a semicolon to support the deprecation message, but I failed to
> notice that when the compiler code loops over switch cases, there is a `continue` statement
> when handling the default case which prevents reaching the code for the deprecation.
>
> I opened a follow-up pull request to fix this, which can hopefully be merged before
> PHP 8.5 is released: https://github.com/php/php-src/pull/20172

Hi Theodore,

Ah! That explains it. Bugs happen to the best of us. Glad to hear I 
didn't misunderstand the intention of the RFC.

Thanks for clarifying and for the new PR to update the deprecation 
implementation. Here's me hoping it will be merged soon.

Smile,
Juliette





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    On 15-10-2025 6:21, Theodore Brown wrote:<br>
    <blockquote
cite="mid:BL4P223MB13645C59490A13076481C3A9DEE8A@BL4P223MB1364.NAMP223.PROD.OUTLOOK.COM"
      type="cite">
      <pre wrap="">On Tue, October 14 2025 at 18:08 Juliette Reinders Folmer wrote:

</pre>
      <blockquote type="cite">
        <pre wrap="">Dear Theodore and list,

I've been looking into the "Deprecate semicolon after case in switch statement" PHP 8.5 deprecation [1]
with the aim of adding a sniff for this to the PHPCompatibility standard and I'm noticing an oddity for
which I would like to clarify whether this is intentional or an oversight.

As demonstrated in the example code provided in the deprecation RFC, both switch `case` condition
statements, as well as `default` statements, can be ended with a semicolon.

So when I first read the RFC, I interpreted the proposal to include both `case` as well as `default`,
as, in my mind, `default` is just a special `case` in a switch.

However, the RFC explicitly only talked about deprecating the use of a semicolon after a
`case` statement and the implementation has followed this to the letter. [2]

The net result of this, is that you can now have a `switch` statement with semicolons
terminating `case` statements and `default` statements, where the former (`case`) will
result in a deprecation notice, while the latter (`default`) will not. For an example, see [3]

This feels inconsistent to me and counter to the intention of the RFC, which is stated to be:

</pre>
        <blockquote type="cite">
          <pre wrap="">Case statements followed by a semicolon can cause confusion, as a developer may think they
behave differently in some way from regular case statements (e.g. preventing fallthrough),
when they do not.
</pre>
        </blockquote>
        <pre wrap="">
Which leaves me wondering what the reason was not to _also_ deprecate the use of a semicolon
to terminate a `default` statement in a switch ? I can't find any discussion about this in the
original mailing list thread [4].

Anyone would care to clarify ?
</pre>
      </blockquote>
      <pre wrap="">
Hi Juliette,

Thank you for pointing out the discrepancy. You are correct that `default` is just a special
case statement, and the intention in the RFC was to output the deprecation message for default cases
as well (the example in the RFC included a default case followed by a semicolon to highlight this).

The fact that a deprecation message isn't shown for default cases is an oversight on my part
when I implemented the RFC. The merged implementation correctly updated the AST for default
case statements followed by a semicolon to support the deprecation message, but I failed to
notice that when the compiler code loops over switch cases, there is a `continue` statement
when handling the default case which prevents reaching the code for the deprecation.

I opened a follow-up pull request to fix this, which can hopefully be merged before
PHP 8.5 is released: <a class="moz-txt-link-freetext" href="https://github.com/php/php-src/pull/20172">https://github.com/php/php-src/pull/20172</a>
</pre>
    </blockquote>
    <br>
    Hi Theodore,<br>
    <br>
    Ah! That explains it. Bugs happen to the best of us. Glad to hear I
    didn't misunderstand the intention of the RFC.<br>
    <br>
    Thanks for clarifying and for the new PR to update the deprecation
    implementation. Here's me hoping it will be merged soon.<br>
    <br>
    Smile,<br>
    Juliette<br>
    <br>
    <br>
    <br>
    <br>
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