Prevent trying to autoload Throwable

[kronthto]

PR for comment in #2273 (comment) .

It will prevent interface_exists from attempting to autoload the SPL interface, which is bound to fail.

With an autoloader implementation that doesn't properly handle not finding a class it can cause warnings (had this issue with the Magento1 autoloader).

The only risk I can think of is very abstract, as I don't think it's common that PHP5 environments would provide a polyfill for \Throwable in autoloaded code.

I didn't figure out how to write a relevant test for this change.

[GrahamCampbell]

Hmmm. I'd say the autoloader should not be crashing the application like that. Warning for classes that don't exist is silly because testing if a class exists is so common.

[riccardomessineo]

This is exactly the PR I was going to submit. Had the same issue with Yii.

[sagikazarmark]

The only risk I can think of is very abstract, as I don't think it's common that PHP5 environments would provide a polyfill for \Throwable in autoloaded code.

Are there any references supporting that claim? I'm not saying it's wrong, but I can't say from the top of my head that they don't.

[kronthto]

symfony/polyfill-php70 for one doesn't do it, the \Error stub extends \Exception and they don't provide a \Throwable.

That's of course not proving some don't.

[sagikazarmark]

After thinking this through, I agree with @GrahamCampbell, an autoloader should not fail when a class does not exist.

My primary concern is breaking polyfills that do provide a Throwable stub.

An easy fix is providing a stub in an environment where the autoloader can't handle the situation, but I think it should be an edge case.

[Nyholm]

According to the PSR4 autoloader specification

4. Autoloader implementations MUST NOT throw exceptions, MUST NOT raise errors of any level, and SHOULD NOT return a value.

I know it sucks that Magento decided to build an autoloader that does not comply with PSR-4. However, I know that newer versions of Magento will fix this issue. =)

I will close this issue since it is not related to Guzzle. Mark also provided a workaround.