Drop PHP 7 support

[thekid]

Scope of Change

This RFC suggests dropping PHP 7 support

Rationale

PHP 7.4 is EOL since November 28, 2022: https://twitter.com/official_php/status/1597203297537957888

Functionality

• Need to simulate PHP 8 Annotations goes away
• We can use named arguments where it makes code more readable
• We can use constructor property promotion to simplify code
• Union types can now be expressed in syntax
• We can refactor several switch statements to match
• We can use the ?-> nullsafe operator

Security considerations

n/a

Speed impact

Better

Dependencies

Major version

Related documents

https://www.php.net/releases/8.0/en.php

[thekid]

As long as it's not a major hassle to support PHP 7.x we can also continue to keep compatibility with it, though.

[thekid]

It could be worthwhile dropping PHP < 7.4 for:

• https://www.php.net/manual/en/functions.arrow.php
• https://wiki.php.net/rfc/spread_operator_for_array
• https://wiki.php.net/rfc/object-typehint (7.2)
• unpack() $offset parameter (7.1)

[thekid]

All PHP 8.0 features @ https://wiki.php.net/rfc#php_80

[thekid]

https://externals.io/message/122214

This would introduce the situation of not being able to write nullable parameters in a way that works for all PHP versions. PHP 7.0 needs T $arg= null, which would be deprecated and create warnings.

One argument more to only keep support for PHP 7.4

[thekid]

This would introduce the situation of not being able to write nullable parameters in a way that works for all PHP versions

Made XP 11 compatible by suppressing this specific error, see https://github.com/xp-framework/core/releases/tag/v11.9.0

[thekid]

The case for dropping 7.0 (but retaining 7.x)

This would introduce the situation of not being able to write nullable parameters in a way that works for all PHP versions

We should safely be able to drop at least PHP 7.0 as even really old Ubuntu versions come with 7.2:

• Ubuntu 22.04: 8.1.x
• Ubuntu 20.04: 7.4.x
• Ubuntu 18.04: 7.2.x

This would allow us to restore full compatibility with the implicit nullable types deprecation as we can use https://wiki.php.net/rfc/nullable_types syntax while still supporting the broadest possible range of PHP versions!

---

Dropping 7.0 would also make these conditionals unnecessary:

$ grep -Hrn PHP_VERSION src/main/php/  | grep 70100
src/main/php/lang/ClassLoader.class.php:231:        $constraint= (PHP_VERSION_ID >= 70100 ? $t->getName() : $t->__toString());
src/main/php/lang/ClassLoader.class.php:233:        $constraint= '\\'.(PHP_VERSION_ID >= 70100 ? $t->getName() : $t->__toString());
src/main/php/lang/ClassLoader.class.php:253:      $decl.= ':'.(PHP_VERSION_ID >= 70100 ? $t->getName() : $t->__toString());
src/main/php/lang/ClassLoader.class.php:255:      $decl.= ': \\'.(PHP_VERSION_ID >= 70100 ? $t->getName() : $t->__toString());
src/main/php/lang/ClassLoader.class.php:303:            if (null !== $t && 'void' === (PHP_VERSION_ID >= 70100 ? $t->getName() : $t->__toString())) {
src/main/php/lang/Environment.class.php:17:    foreach (PHP_VERSION_ID >= 70100 ? getenv() : $_SERVER as $name => $value) {
src/main/php/lang/Environment.class.php:32:    $variables= PHP_VERSION_ID >= 70100 ? getenv() : $_SERVER;
src/main/php/lang/reflect/Field.class.php:99:      $name= PHP_VERSION_ID >= 70100 ? $t->getName() : $t->__toString();
src/main/php/lang/reflect/Parameter.class.php:107:      $name= PHP_VERSION_ID >= 70100 ? $t->getName() : $t->__toString();
src/main/php/lang/reflect/Routine.class.php:168:      $name= PHP_VERSION_ID >= 70100 ? $t->getName() : $t->__toString();
src/main/php/lang/Type.class.php:256:      $name= PHP_VERSION_ID >= 70100 ? $type->getName() : $type->__toString();

---

PHP 7.1 comes with a variety of syntactical features:

• Nullable Types
• Square bracket syntax for array destructuring assignment
• Allow specifying keys in list()
• Iterable
• Void Return Type
• Multi catch

See https://wiki.php.net/rfc#php_71

PHP 7.2, 7.3 and 7.4 offer the following on top:

• Object typehint
• Trailing commas in list syntax
• list() Reference Assignment
• Flexible Heredoc and Nowdoc Syntaxes
• New custom object serialization mechanism
• Null Coalesce Equal Operator
• Typed Properties 2.0
• Arrow functions 2.0
• Spread Operator in Array Expression
• Numeric Literal Separator

See https://wiki.php.net/rfc#php_72, https://wiki.php.net/rfc#php_73 and https://wiki.php.net/rfc#php_74

---

Our path forward could be as follows:

1. XP 12 drops PHP 7.0 support
   • Released in the next couple of days
   • Minimum requirement: PHP 7.1
   • Migrates to no longer Suppress implicitly nullable parameter types warnings core#337
   • Removes deprecated XP annotation syntax as stated in Adopt PHP 8 annotation syntax #336
   • Keeps XP reflection API - see Extract reflection to its own library #338
2. XP 13 drops PHP 7.1 - 7.3 support
   • Released November 2024, two years after PHP 7.4 EOL
   • Minimum requirement: PHP 7.4
   • Removes XP relection API
3. XP 14 drops PHP 7 support alltogether
   • Released 2025
   • Minimum requirement: PHP 8.0

Alternatively, a more "agressive" (see above for how long PHP 7.4 has been EOL) path could be:

1. XP 12 drops PHP 7.0 - 7.3 support
   • Released in the next couple of days
   • Minimum requirement: PHP 7.4
   • Migrates to no longer Suppress implicitly nullable parameter types warnings core#337
   • Removes deprecated XP annotation syntax as stated in Adopt PHP 8 annotation syntax #336
   • Keeps XP reflection API - see Extract reflection to its own library #338
2. XP 13 drops PHP 7 support alltogether
   • Released November 2024, two years after PHP 7.4 EOL
   • Minimum requirement: PHP 8.0
   • Removes XP relection API

[thekid]

For contrast: Symfony, Laravel and PHPUnit all require PHP 8.2 at the time of writing