Clarify PHP version support

[totten]

The disposition of PHP version support is a bit confusing. I was expecting it to work on 7.1.3+ b/c composer.json pointed to that version.

Below are a couple different procedures to see the confusion.

Steps to reproduce (A)

• Open a shell with PHP 7.1.33.
• Download the current robo.phar (2.1.0).
• Run robo --help

Expected behavior (A)

Show help screen

Actual behavior (A)

$ ./robo.phar --help
PHP Fatal error:  Uncaught Error: Call to undefined function Symfony\Component\Console\Output\stream_isatty() in  phar:///home/myuser/bin/robo/vendor/symfony/console/Output/StreamOutput.php:113
Stack trace:
#0 phar:///home/myuser/bin/robo/vendor/symfony/console/Output/StreamOutput.php(51): Symfony\Component\Console\Output\StreamOutput->hasColorSupport()
#1 phar:///home/myuser/bin/robo/vendor/symfony/console/Output/ConsoleOutput.php(42): Symfony\Component\Console\Output\StreamOutput->__construct(Resource id #45, 32, NULL, NULL)
#2 phar:///home/myuser/bin/robo/src/Runner.php(107): Symfony\Component\Console\Output\ConsoleOutput->__construct()
#3 phar:///home/myuser/bin/robo/src/Runner.php(264): Robo\Runner->loadRoboFile(NULL)
#4 phar:///home/myuser/bin/robo/src/Runner.php(155): Robo\Runner->getRoboFileCommands(NULL)
#5 /home/myuser/bin/robo(50): Robo\Runner->execute(Array)
#6 {main}
  thrown in phar:///home/myuser/bin/robo/vendor/symfony/console/Output/StreamOutput.php on line 113

Upon inspection, the PHAR file is missing the stream_isatty() polyfill from symfony/polyfill-php72.

Steps to reproduce (B)

• Open a shell with PHP 7.1.33.
• Clone https://github.com/consolidation/Robo/
• Run composer install
• Run ./robo --help

Expected behavior (B)

Show help screen

Actual behavior (B)

[bknix-min:/tmp/Robo] ./robo --help

PHP Fatal error:  Declaration of Symfony\Contracts\EventDispatcher\EventDispatcherInterface::dispatch(Symfony\Contracts\EventDispatcher\object $event, ?string $eventName = NULL): Symfony\Contracts\EventDispatcher\object must be compatible with Psr\EventDispatcher\EventDispatcherInterface::dispatch(Psr\EventDispatcher\object $event) in /tmp/Robo/vendor/symfony/event-dispatcher-contracts/EventDispatcherInterface.php on line 19
PHP Stack trace:
PHP   1. {main}() /tmp/Robo/robo:0
PHP   2. Robo\Runner->execute() /tmp/Robo/robo:48
PHP   3. Robo\Runner->run() /tmp/Robo/src/Runner.php:156
PHP   4. Robo\Robo::createDefaultContainer() /tmp/Robo/src/Runner.php:214
PHP   5. Robo\Robo::configureContainer() /tmp/Robo/src/Robo.php:161
PHP   6. League\Container\Container->share() /tmp/Robo/src/Robo.php:242
PHP   7. League\Container\Container->add() /tmp/Robo/vendor/league/container/src/Container.php:163
PHP   8. League\Container\Definition\DefinitionFactory->getDefinition() /tmp/Robo/vendor/league/container/src/Container.php:142
PHP   9. class_exists() /tmp/Robo/vendor/league/container/src/Definition/DefinitionFactory.php:20
PHP  10. spl_autoload_call() /tmp/Robo/vendor/league/container/src/Definition/DefinitionFactory.php:20
PHP  11. Composer\Autoload\ClassLoader->loadClass() /tmp/Robo/vendor/league/container/src/Definition/DefinitionFactory.php:20
PHP  12. Composer\Autoload\includeFile() /tmp/Robo/vendor/composer/ClassLoader.php:322
PHP  13. include() /tmp/Robo/vendor/composer/ClassLoader.php:444
PHP  14. spl_autoload_call() /tmp/Robo/vendor/symfony/event-dispatcher/EventDispatcher.php:32
PHP  15. Composer\Autoload\ClassLoader->loadClass() /tmp/Robo/vendor/symfony/event-dispatcher/EventDispatcher.php:32
PHP  16. Composer\Autoload\includeFile() /tmp/Robo/vendor/composer/ClassLoader.php:322
PHP  17. include() /tmp/Robo/vendor/composer/ClassLoader.php:444
PHP  18. spl_autoload_call() /tmp/Robo/vendor/symfony/event-dispatcher/EventDispatcherInterface.php:23
PHP  19. Composer\Autoload\ClassLoader->loadClass() /tmp/Robo/vendor/symfony/event-dispatcher/EventDispatcherInterface.php:23
PHP  20. Composer\Autoload\includeFile() /tmp/Robo/vendor/composer/ClassLoader.php:322
PHP  21. include() /tmp/Robo/vendor/composer/ClassLoader.php:444

Upon inspection, composer.json actually has two slightly contradictory statements:

• require: php is >=7.1.3
• config: platform: php is 7.2.28.

It could make sense if the intent is to offer different levels of support for different scenarios, eg

• Downstream consumers who use robo as a library - for which the minimum is 7.1.
• Downstream consumers who use robo as an application/PHAR - for which the minimum is 7.2.

Note: I locally edited the config: platform: php to pin to 7.1.3 and cleared composer.lock / vendor. Given appropriate dependencies, ./robo --help was fine.

System Configuration

• PHP 7.1.33 (specifically via civicrm-buildkit/nix/profiles/min.
• nix 2.3.7 on Ubuntu 20.04

Suggestions

• If the intent is to consistently support PHP 7.1+, then change config: platform: php to 7.1.
• If the intent is to consistently support PHP 7.2+, then change require: php to 7.2.
• If the intent is to some kind of mixed-support situation, then keep composer.json -- but update the application's entrypoint (./robo?) to check the version and give an error message to explain the mixed-support.

[greg-1-anderson]

I clarified the PHP version support intentions in the README. The platform.php setting is 7.2 because that is the PHP version required by Symfony 5. Symfony 4 and PHP 7.1 are also supported when using Robo as a library.