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Date: Mon, 23 Sep 2019 22:14:36 +0200
Message-ID: <CAG9XoMRuvecyBQfB7fYEkO2=evdZ1wBHYVWioOcOMTJyObe2bQ@mail.gmail.com>
To: Nikita Popov <nikita.ppv@gmail.com>
Cc: PHP internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary="000000000000470a5705933e121a"
Subject: Re: [PHP-DEV] Re: [RFC] Union Types v2
From: benjamin.morel@gmail.com (Benjamin Morel)

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Hi Nikita,

Thank you for your work on this, I look forward to being able to use union
types!

The one thing that bothers me a bit is introducing yet another
inconsistency by supporting false and not true as a type. Sure, I do get
the need for false as a valid type for historical reasons, but at the same
time I thought it would be interesting to see if true was being used as
well in the wild, before closing the door on it.

Therefore I reviewed all Composer packages with > 1 million downloads (1211
packages total), and here are the results:

*31 packages
<https://gist.github.com/BenMorel/56dfff576b1d8a719cd71b14ef614d2e#file-pac=
kages-txt>
use at least one @var,  @param or @return containing true as a type.*

- there are many illegitimate use cases, such as @return true
<https://github.com/drupal/core/blob/c447ebb6a89149ef86e0af06bc00fec63027ec=
0d/modules/views/src/ViewExecutable.php#L719>
, @return bool|true
<https://github.com/php-http/message/blob/144d13ba024d0c597830636907144bc7c=
23f50dd/src/Authentication/AutoBasicAuth.php#L23>,
@return true|false
<https://github.com/zendframework/zend-form/blob/ff4c9ec32d141e4ac622c2aa40=
a8c9eb77a40725/src/Annotation/AnnotationBuilder.php#L412>,
or even @return bool|true|false
<https://github.com/slevomat/coding-standard/blob/964a3ff08d7ee924510c3b705=
f826165adaa97fe/tests/Sniffs/Namespaces/data/fullyQualifiedClassNameInAnnot=
ationNoErrors.php#L41>
- there are, however, quite a few potentially legitimate use cases. Among
others:

- @return true|WP_Error
<https://github.com/johnpbloch/wordpress-core/blob/4a96ef28019f3f529465eac7=
1c718afea2c88e8b/wp-includes/rest-api/class-wp-rest-request.php#L641>
 (*johnpbloch/wordpress-core*) : "True if the JSON data was passed or no
JSON data was provided, WP_Error if invalid JSON was passed."
- @return true|string
<https://github.com/johnpbloch/wordpress-core/blob/bd27b2bc49483b796fdb228f=
9b0614f9880823ee/wp-includes/ms-load.php#L72>
 (*johnpbloch/wordpress-core*) : "Returns true on success, or drop-in file
to include."
- @return string|true
<https://github.com/PHP-DI/PHP-DI/blob/b891248f04c594dae4c07650bc0815d0dc81=
bacb/src/Compiler/Compiler.php#L317>
 (*php/di*) : True if compilable, string explaining why if not
- @return string|true
<https://github.com/zendframework/zend-authentication/blob/86d6553e1cfe5ed2=
bde53cbea9fd162c6875a9c8/src/Adapter/Ldap.php#L378>
 (*zendframework/zend-authentication*) : True if successfull, error message
if not
- @param int|true
<https://github.com/yiisoft/yii2/blob/fdbe45af3a4f923a97b718d8694981e1e1954=
03d/framework/db/Query.php#L1266>
(*yiisoft/yii2*) : "Use 0 to indicate that..., Use a negative number to
indicate that..., Use boolean `true` to indicate that ..."
- @param callable|resource|string|true|null
<https://github.com/symfony/symfony/blob/242f24427d34bd47ef0e3a027a5a4e979d=
713c6f/src/Symfony/Component/VarDumper/Dumper/AbstractDumper.php#L117>
(*symfony/symfony*) : "A line dumper callable, an opened stream, an output
path or true to return the dump"

Full list here
<https://gist.github.com/BenMorel/56dfff576b1d8a719cd71b14ef614d2e#file-typ=
es-txt>
.

So although true as a type does not have the same historical background as
false, it does seem that it's being used by enough packages to be worth
considering; what do you think?

=E2=80=94 Benjamin

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