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Subject: Re: [PHP-DEV] Deprecate return by reference from never ?
Date: Wed, 9 Jul 2025 08:48:02 +0200
In-Reply-To: <686DBC13.4010704@adviesenzo.nl>
Cc: php internals <internals@lists.php.net>
To: Juliette Reinders Folmer <php-internals_nospam@adviesenzo.nl>
References: <686DBC13.4010704@adviesenzo.nl>
From: claude.pache@gmail.com (Claude Pache)


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> Le 9 juil. 2025 =C3=A0 02:47, Juliette Reinders Folmer =
<php-internals_nospam@adviesenzo.nl> a =C3=A9crit :
>=20
> L.S.,
>=20
> I just noticed something which seems odd to me: PHP 8.1 deprecated =
declaring a function to return by reference when the return type is =
void:
>=20
> `function &foo() : void {}` results in:
> "Deprecated: foo(): Returning by reference from a void function is =
deprecated"
>=20
> However, declaring a function to return by reference when the return =
type is "never" does not yield either an error or a deprecation notice: =
https://3v4l.org/DWs7t
>=20
> I might well be missing something, but this feels a bit strange and =
inconsistent to me.
>=20
> Should this be fixed by also deprecating return by reference for =
"never" functions ?
>=20
> Smile,
> Juliette
>=20
> =20

Hi Juliette,

The two cases are subtly different, and this can be illustrated by the =
following example:

Suppose you have an interface mandating to implement a method that =
returns something by reference.
When you implement that interface, you must provide a method that =
returns by reference, but you are free to actually never return from =
it=E2=80=94restricting the return type to `never`.
On the other hand, you cannot implement it with a method that doesn=E2=80=99=
t provide a value when returning=E2=80=94changing the return type to =
`void`.

In other words, although the combination of =E2=80=9Cby reference=E2=80=9D=
 and =E2=80=9Cnever=E2=80=9D is not useful in isolation, it makes =
nevertheless sense when you think of =E2=80=9Cnever=E2=80=9D as a =
special case of =E2=80=9Ca value that satisfies a set of constraints=E2=80=
=9D.

=E2=80=94Claude=

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<html><head><meta http-equiv=3D"content-type" content=3D"text/html; =
charset=3Dutf-8"></head><body style=3D"overflow-wrap: break-word; =
-webkit-nbsp-mode: space; line-break: after-white-space;"><br =
id=3D"lineBreakAtBeginningOfMessage"><div><br><blockquote =
type=3D"cite"><div>Le 9 juil. 2025 =C3=A0 02:47, Juliette Reinders =
Folmer &lt;php-internals_nospam@adviesenzo.nl&gt; a =C3=A9crit =
:</div><br class=3D"Apple-interchange-newline"><div>
 =20

    <meta http-equiv=3D"content-type" content=3D"text/html; =
charset=3Dutf-8">
 =20
  <div bgcolor=3D"#FFFFFF" text=3D"#000000">
    <font size=3D"-1"><font face=3D"Verdana">L.S.,<br>
        <br>
        I just noticed something which seems odd to me: PHP 8.1
        deprecated declaring a function to return by reference when the
        return type is void:<br>
        <br>
        `function &amp;foo() : void {}` results in:<br>
        "Deprecated: foo(): Returning by reference from a void function
        is deprecated"<br>
        <br>
        However, declaring a function to return by reference when the
        return type is "never" does not yield either an error or a
        deprecation notice: <a class=3D"moz-txt-link-freetext" =
href=3D"https://3v4l.org/DWs7t">https://3v4l.org/DWs7t</a><br>
        <br>
        I might well be missing something, but this feels a bit strange
        and inconsistent to me.<br>
        <br>
        Should this be fixed by also deprecating return by reference for
        "never" functions ?<br>
        <br>
        Smile,<br>
        Juliette<br>
        <br>
        =
&nbsp;<br></font></font></div></div></blockquote><div><br></div><div>Hi =
Juliette,</div><div><br></div><div>The two cases are subtly different, =
and this can be illustrated by the following =
example:</div><div><br></div><div>Suppose you have an interface =
mandating to implement a method that returns something by =
reference.</div><div>When you implement that interface, you must provide =
a method that returns by reference, but you are free to actually never =
return from it=E2=80=94restricting the return type to =
`never`.</div><div>On the other hand, you cannot implement it with a =
method that doesn=E2=80=99t provide a value when returning=E2=80=94changin=
g the return type to `void`.</div><div><br></div><div>In other words, =
although the combination of =E2=80=9Cby reference=E2=80=9D and =
=E2=80=9Cnever=E2=80=9D is not useful in isolation, it makes =
nevertheless sense when you think of =E2=80=9Cnever=E2=80=9D as a =
special case of =E2=80=9Ca value that satisfies a set of =
constraints=E2=80=9D.</div><div><br></div><div>=E2=80=94Claude</div></div>=
</body></html>=

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