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Date: Sat, 21 Feb 2026 01:29:07 +0700
Message-ID: <CAEZPtU7pY1stp6WXpoUHnx-X_tBtvjK7x1Vi9vJDg6fC0soV1g@mail.gmail.com>
Subject: Re: [PHP-DEV] [IDEA for RFC] let the "new" operator fail when the
 __construct() function returns a value.
To: Mirco Babin <mirco.babin@gmail.com>
Cc: "Rowan Tommins [IMSoP]" <imsop.php@rwec.co.uk>, PHP internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary="00000000000072546c064b4599a9"
From: pierre.php@gmail.com (Pierre Joye)

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Hello Mirco,




On Fri, Feb 20, 2026, 11:48=E2=80=AFPM Mirco Babin <mirco.babin@gmail.com> =
wrote:

> Op vr 20 feb 2026 om 08:43 schreef Rowan Tommins [IMSoP] <
> imsop.php@rwec.co.uk>:
> >
> > On 19 February 2026 20:24:56 GMT, Mirco Babin <mirco.babin@gmail.com>
> wrote:
> >
> >
> > >The Php scripting aspect makes it difficult in general
> > >for untyped projects to fail early.
> >
> >
> > This is a completely irrelevant statement. We're not talking about
> > failing early "in general", we're talking about a compile-time check
> > that PHP already makes in other contexts.
>
> Failing early is not always possible. The compiler can not always infere
> the correct return type. E.g. this example will succeed to compile:
>
> ```php
> class UnableToInfereReturnType
> {
>     private function TruelyUnknown() : mixed
>     {
>         $a =3D time();
>         if ($a % 2 =3D=3D=3D 0) {
>             return ['important'];
>         }
>     }
>
>     private function ActAsVoid() : void
>     {
>         return $this->TruelyUnknown();
>     }
>
>     // Lets act as if the return type is implicitly void
>     public function __construct() // : void
>     {
>         return $this->ActAsVoid();
>     }
> }
>
> $it =3D new UnableToInfereReturnType();
>
> // Runtime error, not a compile error.
> // Fatal error: A void method must not return a value in /in/MJCjX on lin=
e
> 15
>

> ```
>

Both can, and should, have errors before runtime.  This is easily detected
at compile time. Whether or not the return <some value> is used in a
branch, it is seen before runtime, obviously.

In a context of __construct, disallow any return value can be detected as
well. Any return statement with anything used with it can be rejected (and
should).

It is documented as void, we could "fix" it with a bug fix.

Also, about this whole discussion , that __ construct, can still be called
as a normal method.  Some relics of php 4-5 migration path and then work
around serialization or hydration challenges.

Most  maintained projects out there moved away from these hacks and rely on
new  reliable solution for these challenges,  like doctrine or symfony
serializer.


If anything,  this whole cleanup could be done right, disallow returning
value and finally make __construct what it is designed and made for, a
constructor. Not a normal method.


__
Pierre

@pierrejoye | http://www.libgd.org

>

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<div dir=3D"auto"><div><div>Hello Mirco,</div><div><br></div><br><br><br><d=
iv class=3D"gmail_quote gmail_quote_container"><div dir=3D"ltr" class=3D"gm=
ail_attr">On Fri, Feb 20, 2026, 11:48=E2=80=AFPM Mirco Babin &lt;<a href=3D=
"mailto:mirco.babin@gmail.com">mirco.babin@gmail.com</a>&gt; wrote:<br></di=
v><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:=
1px #ccc solid;padding-left:1ex">Op vr 20 feb 2026 om 08:43 schreef Rowan T=
ommins [IMSoP] &lt;<a href=3D"mailto:imsop.php@rwec.co.uk" target=3D"_blank=
" rel=3D"noreferrer">imsop.php@rwec.co.uk</a>&gt;:<br>
&gt;<br>
&gt; On 19 February 2026 20:24:56 GMT, Mirco Babin &lt;<a href=3D"mailto:mi=
rco.babin@gmail.com" target=3D"_blank" rel=3D"noreferrer">mirco.babin@gmail=
.com</a>&gt; wrote:<br>
&gt;<br>
&gt;<br>
&gt; &gt;The Php scripting aspect makes it difficult in general<br>
&gt; &gt;for untyped projects to fail early.<br>
&gt;<br>
&gt;<br>
&gt; This is a completely irrelevant statement. We&#39;re not talking about=
<br>
&gt; failing early &quot;in general&quot;, we&#39;re talking about a compil=
e-time check<br>
&gt; that PHP already makes in other contexts.<br>
<br>
Failing early is not always possible. The compiler can not always infere<br=
>
the correct return type. E.g. this example will succeed to compile:<br>
<br>
```php<br>
class UnableToInfereReturnType<br>
{<br>
=C2=A0 =C2=A0 private function TruelyUnknown() : mixed<br>
=C2=A0 =C2=A0 {<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 $a =3D time();<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 if ($a % 2 =3D=3D=3D 0) {<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 return [&#39;important&#39;];<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 }<br>
=C2=A0 =C2=A0 }<br>
<br>
=C2=A0 =C2=A0 private function ActAsVoid() : void<br>
=C2=A0 =C2=A0 {<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 return $this-&gt;TruelyUnknown();<br>
=C2=A0 =C2=A0 }<br>
<br>
=C2=A0 =C2=A0 // Lets act as if the return type is implicitly void<br>
=C2=A0 =C2=A0 public function __construct() // : void<br>
=C2=A0 =C2=A0 {<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 return $this-&gt;ActAsVoid();<br>
=C2=A0 =C2=A0 }<br>
}<br>
<br>
$it =3D new UnableToInfereReturnType();<br>
<br>
// Runtime error, not a compile error.<br>
// Fatal error: A void method must not return a value in /in/MJCjX on line =
15<br></blockquote></div></div><div dir=3D"auto"><div class=3D"gmail_quote =
gmail_quote_container"><blockquote class=3D"gmail_quote" style=3D"margin:0 =
0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><br>
```<br></blockquote></div></div><div dir=3D"auto"><br></div><div dir=3D"aut=
o">Both can, and should, have errors before runtime.=C2=A0 This is easily d=
etected at compile time. Whether or not the return &lt;some value&gt; is us=
ed in a branch, it is seen before runtime, obviously.=C2=A0</div><div dir=
=3D"auto"><br></div><div dir=3D"auto">In a context of __construct, disallow=
 any return value can be detected as well. Any return statement with anythi=
ng used with it can be rejected (and should).=C2=A0</div><div dir=3D"auto">=
<br></div><div dir=3D"auto">It is documented as void, we could &quot;fix&qu=
ot; it with a bug fix.</div><div dir=3D"auto"><br></div><div dir=3D"auto">A=
lso, about this whole discussion , that __ construct, can still be called a=
s a normal method.=C2=A0 Some relics of php 4-5 migration path and then wor=
k around serialization or hydration challenges.</div><div dir=3D"auto"><br>=
</div><div dir=3D"auto">Most=C2=A0 maintained projects out there moved away=
 from these hacks and rely on new=C2=A0 reliable solution for these challen=
ges,=C2=A0 like doctrine or symfony serializer.</div><div dir=3D"auto"><br>=
</div><div dir=3D"auto"><br></div><div dir=3D"auto">If anything,=C2=A0 this=
 whole cleanup could be done right, disallow returning value and finally ma=
ke __construct what it is designed and made for, a constructor. Not a norma=
l method.=C2=A0</div><div dir=3D"auto"><br></div><div dir=3D"auto">=C2=A0</=
div><div dir=3D"auto">__</div><div dir=3D"auto">Pierre</div><div dir=3D"aut=
o"><br></div><div dir=3D"auto">@pierrejoye | <a href=3D"http://www.libgd.or=
g">http://www.libgd.org</a></div><div dir=3D"auto"><div class=3D"gmail_quot=
e gmail_quote_container"><blockquote class=3D"gmail_quote" style=3D"margin:=
0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
</blockquote></div></div></div>

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