Possible Bug with Interface, Constants and Inheritance

9 years ago by k@rl.pflaesterer.de — view source — reply

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Hi,
I'm not sure if it's a bug or not.

Consider these simple script:

<?php
interface I1 { const C1 = '';}
class C3 implements I1 { const C1 = 'c2';}
$c3 = new C3;
var_dump($c3::C1);

That gives a fatal error with mod_php and PHP CLI if I call the CLI
version with a file name:

PHP Fatal error: Cannot inherit previously-inherited or override
constant C1 from interface I1 in

If I use the CLI and enter the code directly it works:

~> php -v
PHP 7.0.7 (cli) (built: May 27 2016 15:22:32) ( NTS )
Copyright (c) 1997-2016 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies
~> php -a -ddispplay_errors=On
Interactive shell

php > interface I1 { const C1 = '';}
php > class C3 implements I1 { const C1 = 'c2';}
php > $c3 = new C3;
php > var_dump($c3::C1);
string(2) "c2"

Is this always the correkt behaviour?

9 years ago by Andreas Heigl — view source — reply

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Am 27.06.16 um 15:01 schrieb Karl Pflästerer:

interface I1 { const C1 = '';}
class C3 implements I1 { const C1 = 'c2';}
$c3 = new C3;
var_dump($c3::C1);

According to https://3v4l.org/jIcs6 it looks like that's intended
behaviour ;)

Cheers

Andreas

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9 years ago by k@rl.pflaesterer.de — view source — reply

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Andreas Heigl andreas@heigl.org writes:

Am 27.06.16 um 15:01 schrieb Karl Pflästerer:

interface I1 { const C1 = '';}
class C3 implements I1 { const C1 = 'c2';}
$c3 = new C3;
var_dump($c3::C1);

According to https://3v4l.org/jIcs6 it looks like that's intended
behaviour ;)

But why does it work in the CLI if I write the code (instead of using a
script)? That's my question.

9 years ago by Christoph Becker — view source — reply

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Andreas Heigl andreas@heigl.org writes:

Am 27.06.16 um 15:01 schrieb Karl Pflästerer:

interface I1 { const C1 = '';}
class C3 implements I1 { const C1 = 'c2';}
$c3 = new C3;
var_dump($c3::C1);

According to https://3v4l.org/jIcs6 it looks like that's intended
behaviour ;)

But why does it work in the CLI if I write the code (instead of using a
script)? That's my question.

Have you tried with and without OPcache?

--
Christoph M. Becker

9 years ago by k@rl.pflaesterer.de — view source — reply

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Am 27.06.16 um 17:04 schrieb Christoph Becker:

Andreas Heigl andreas@heigl.org writes:

Am 27.06.16 um 15:01 schrieb Karl Pflästerer:

interface I1 { const C1 = '';}
class C3 implements I1 { const C1 = 'c2';}
$c3 = new C3;
var_dump($c3::C1);

According to https://3v4l.org/jIcs6 it looks like that's intended
behaviour ;)

But why does it work in the CLI if I write the code (instead of using a
script)? That's my question.

Have you tried with and without OPcache?

There is no opcache in use. (Don't know if the message can be seen on
the list; I only could read it in my mailbox; I could'nt see it in Gmane).

9 years ago by Andreas Heigl — view source — reply

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Am 27.06.16 um 15:28 schrieb Karl Pflästerer:

Andreas Heigl andreas@heigl.org writes:

Am 27.06.16 um 15:01 schrieb Karl Pflästerer:

interface I1 { const C1 = '';}
class C3 implements I1 { const C1 = 'c2';}
$c3 = new C3;
var_dump($c3::C1);

According to https://3v4l.org/jIcs6 it looks like that's intended
behaviour ;)

But why does it work in the CLI if I write the code (instead of using a
script)? That's my question.

It doesn't. At least not on my machine. This is the output I get:

$ php -v
PHP 7.1.0alpha2 (cli) (built: Jun 24 2016 13:50:28) ( NTS )
Copyright (c) 1997-2016 The PHP Group
Zend Engine v3.1.0-dev, Copyright (c) 1998-2016 Zend Technologies

$ php -a
Interactive shell

php > interface I1 { const C1 = '';}
php > class C3 implements I1 { const C1 = 'c2';}
PHP Fatal error:  Cannot inherit previously-inherited or override

constant C1 from interface I1 in php shell code on line 1

Fatal error: Cannot inherit previously-inherited or override

constant C1 from interface I1 in php shell code on line 1
php > $c3 = new C3;
php > var_dump($c3::C1);
string(2) "c2"
php >

So it crashes with a fatal error when Implementing the interface. It'S
interesting though that the script allows me to instantiate the class
nonetheless. That's right.

Perhaps some C-Guru can shed some light here?

Cheers

Andreas

9 years ago by Bishop Bettini — view source — reply

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> Am 27.06.16 um 15:28 schrieb Karl Pflästerer:
> > Andreas Heigl writes:
> >
> >> Am 27.06.16 um 15:01 schrieb Karl Pflästerer:
> >>> interface I1 { const C1 = '';}
> >>> class C3 implements I1 { const C1 = 'c2';}
> >>> $c3 = new C3;
> >>> var_dump($c3::C1);
> >>
> >> According to https://3v4l.org/jIcs6 it looks like that's intended
> >> behaviour ;)
> >
> > But why does it work in the CLI if I write the code (instead of using a
> > script)? That's my question.
>
> It doesn't. At least not on my machine. This is the output I get:
>
> $ php -v
> PHP 7.1.0alpha2 (cli) (built: Jun 24 2016 13:50:28) ( NTS )
> Copyright (c) 1997-2016 The PHP Group
> Zend Engine v3.1.0-dev, Copyright (c) 1998-2016 Zend Technologies
>

Technically, this is a different version than reported. Nonetheless, on the
same version my REPL complains as well, I suspect because the original
report misspelled the INI setting ("-ddispplay_errors=On", notice the
double "p"):

$ php -v
PHP 7.0.7 (cli) (built: May 28 2016 08:26:36) ( NTS )
Copyright (c) 1997-2016 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies
with Zend OPcache v7.0.6-dev, Copyright (c) 1999-2016, by Zend
Technologies
with Xdebug v2.4.0, Copyright (c) 2002-2016, by Derick Rethans

$ php -a
Interactive shell

php > interface I1 { const C1 = ''; }
php > class C3 implements I1 { const C1 = 'c2'; }
PHP Fatal error: Cannot inherit previously-inherited or override constant
C1 from interface I1 in php shell code on line 1
PHP Stack trace:
PHP 1. {main}() php shell code:0

> So it crashes with a fatal error when Implementing the interface. It'S
> interesting though that the script allows me to instantiate the class
> nonetheless. That's right.
>

Under normal interpretive operation, the Fatal terminates the script. But
in the case of the REPL command line, those are swallowed up and you can
keep going. Same as like:

php > foo();
PHP Warning: Uncaught Error: Call to undefined function foo() in php shell
code:1
Stack trace:
#0 {main}
thrown in php shell code on line 1
PHP Stack trace:
PHP 1. {main}() php shell code:0
php > echo 'hi';
hi

I'm not seeing any bugs here.

bishop

9 years ago by Andreas Heigl — view source — reply

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Am 27.06.16 um 17:41 schrieb Bishop Bettini:
>
>
>> Am 27.06.16 um 15:28 schrieb Karl Pflästerer:
>>> Andreas Heigl writes:
>>>
>>>> Am 27.06.16 um 15:01 schrieb Karl Pflästerer:
>>>>> interface I1 { const C1 = '';}
>>>>> class C3 implements I1 { const C1 = 'c2';}
>>>>> $c3 = new C3;
>>>>> var_dump($c3::C1);
>>>>
>>>> According to https://3v4l.org/jIcs6 it looks like that's intended
>>>> behaviour ;)
>>>
>>> But why does it work in the CLI if I write the code (instead of using a
>>> script)? That's my question.
>>
>> It doesn't. At least not on my machine. This is the output I get:
>>
>> $ php -v
>> PHP 7.1.0alpha2 (cli) (built: Jun 24 2016 13:50:28) ( NTS )
>> Copyright (c) 1997-2016 The PHP Group
>> Zend Engine v3.1.0-dev, Copyright (c) 1998-2016 Zend Technologies
>>
>
> Technically, this is a different version than reported. Nonetheless, on the
> same version my REPL complains as well, I suspect because the original
> report misspelled the INI setting ("-ddispplay_errors=On", notice the
> double "p"):
>
> $ php -v
> PHP 7.0.7 (cli) (built: May 28 2016 08:26:36) ( NTS )
> Copyright (c) 1997-2016 The PHP Group
> Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies
> with Zend OPcache v7.0.6-dev, Copyright (c) 1999-2016, by Zend
> Technologies
> with Xdebug v2.4.0, Copyright (c) 2002-2016, by Derick Rethans
>
> $ php -a
> Interactive shell
>
> php > interface I1 { const C1 = ''; }
> php > class C3 implements I1 { const C1 = 'c2'; }
> PHP Fatal error: Cannot inherit previously-inherited or override constant
> C1 from interface I1 in php shell code on line 1
> PHP Stack trace:
> PHP 1. {main}() php shell code:0
>
>
>
>> So it crashes with a fatal error when Implementing the interface. It'S
>> interesting though that the script allows me to instantiate the class
>> nonetheless. That's right.
>>
>
> Under normal interpretive operation, the Fatal terminates the script. But
> in the case of the REPL command line, those are swallowed up and you can
> keep going. Same as like:
>
> php > foo();
> PHP Warning: Uncaught Error: Call to undefined function foo() in php shell
> code:1
> Stack trace:
> #0 {main}
> thrown in php shell code on line 1
> PHP Stack trace:
> PHP 1. {main}() php shell code:0
> php > echo 'hi';
> hi
>
> I'm not seeing any bugs here.

Thanks for the info.

What I find strange is that I can instantiate the class "C3" even though
the declaration of the class is broken. I wouldn't say it's a bug, but
interesting.

Cheers

Andreas

--
,,,
(o o)
+---------------------------------------------------------ooO-(_)-Ooo-+
| Andreas Heigl |
| mailto:andreas@heigl.org N 50°22'59.5" E 08°23'58" |
| http://andreas.heigl.org http://hei.gl/wiFKy7 |
+---------------------------------------------------------------------+
| http://hei.gl/root-ca |
+---------------------------------------------------------------------+

9 years ago by k@rl.pflaesterer.de — view source — reply

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Bishop Bettini writes:

>
>
>> Am 27.06.16 um 15:28 schrieb Karl Pflästerer:
>> > Andreas Heigl writes:
>> >
>> >> Am 27.06.16 um 15:01 schrieb Karl Pflästerer:
>> >>> interface I1 { const C1 = '';}
>> >>> class C3 implements I1 { const C1 = 'c2';}
>> >>> $c3 = new C3;
>> >>> var_dump($c3::C1);
>> >>
>> >> According to https://3v4l.org/jIcs6 it looks like that's intended
>> >> behaviour ;)
>> >
>> > But why does it work in the CLI if I write the code (instead of using a
>> > script)? That's my question.
>>
>> It doesn't. At least not on my machine. This is the output I get:
>>
>> $ php -v
>> PHP 7.1.0alpha2 (cli) (built: Jun 24 2016 13:50:28) ( NTS )
>> Copyright (c) 1997-2016 The PHP Group
>> Zend Engine v3.1.0-dev, Copyright (c) 1998-2016 Zend Technologies
>>
>
> Technically, this is a different version than reported. Nonetheless, on the
> same version my REPL complains as well, I suspect because the original
> report misspelled the INI setting ("-ddispplay_errors=On", notice the
> double "p"):

[...]

Thanks; that explains why I didn't see the error message.

>
> Under normal interpretive operation, the Fatal terminates the script. But
> in the case of the REPL command line, those are swallowed up and you can
> keep going. Same as like:
>

And that explains why I was able to instantiate a broken class (with a
overriden constant).

So no bug but an interesting edge case.

KP

9 years ago by Rowan Collins — view source — reply

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So it crashes with a fatal error when Implementing the interface. It'S
interesting though that the script allows me to instantiate the class
nonetheless.

It sounds to me like the ability of the interactive shell to catch fatal
errors and continue allows you to execute code with the engine in a
bogus state.

It's possible to do all sorts of wacky things that way:

php > class Bogus implements NonExistent {}
PHP Fatal error: Interface 'NonExistent' not found in php shell code on
line 1

Fatal error: Interface 'NonExistent' not found in php shell code on line 1
php > $b = new Bogus;
php > var_dump($b);
object(Bogus)#1 (0) {
}
php > var_dump($b instanceOf NonExistent);
bool(false)
php > var_dump($b instanceOf Bogus);
bool(true)

PHP Fatal error: Cannot inherit previously-inherited or override
constant C1 from interface I1 in

Can I just say this is a positively hideous error message. I can't
actually figure out how to parse its grammar: is it (inherit
previously-inherited) OR (override)? If so, what does "inherit
previously-inherited" mean?

9 years ago by Bishop Bettini — view source — reply

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On Mon, Jun 27, 2016 at 11:44 AM, Rowan Collins rowan.collins@gmail.com
wrote:

PHP Fatal error: Cannot inherit previously-inherited or override

constant C1 from interface I1 in

Can I just say this is a positively hideous error message. I can't
actually figure out how to parse its grammar: is it (inherit
previously-inherited) OR (override)? If so, what does "inherit
previously-inherited" mean?

+1 on hideous.

From this test
https://github.com/php/php-src/blob/master/Zend/tests/errmsg_025.phpt, I
believe "previously-inherited" refers to this situation:

interface I1 { const BAR = 242; }
interface I2 { const BAR = 242; }
class Foo implements I1, I2 { };