[5.8] fix MorphTo Relation ignores parent $timestamp when touching

[mx2s]

Fixed bug with touching model which has $timestamps set to false resulting in Illuminate\Database\QueryException: SQLSTATE[HY000]: General error: 1 no such column: updated_at

for source issue and more details see #28638

[mx2s]

@driesvints reopened #28658

[staudenmeir]

We also have to cover cases where timestamps are enabled, but UPDATED_AT is null:

framework/src/Illuminate/Database/Eloquent/Builder.php

Lines 861 to 864 in 0ef0134

	if (! $this->model->usesTimestamps() ||
	is_null($this->model->getUpdatedAtColumn())) {
	return $values;
	}

[staudenmeir]

I would prefer (new $class)->usesTimestamps() to be consistent with existing code.

[mx2s]

We also have to cover cases where timestamps are enabled, but UPDATED_AT is null:

just added test

[mx2s]

@staudenmeir in some cases we're getting abstract classes here for ex.

framework/tests/Database/DatabaseEloquentIntegrationTest.php

Line 1539 in 5992f10

$this->assertFalse(Model::isIgnoringTouch());

[staudenmeir]

Yes, but only in the tests. You can't get an abstract class in a real application. Please adjust the test accordingly.

[mx2s]

Yes, but only in the tests. You can't get an abstract class in a real application.

OK, but If I use (new $class)->usesTimestamps() 6 more test are failing (not including mine) - what to do with that?
For example this one:

framework/tests/Database/DatabaseEloquentIntegrationTest.php

Line 1539 in 5992f10

$this->assertFalse(Model::isIgnoringTouch());

[staudenmeir]

I think we should move the new code to Relation::touch(). Model::isIgnoringTouch() is only about $ignoreOnTouch, not about timestamps.

[staudenmeir]

This case has to return true. You need to cover it by adjusting isIgnoringTouch().

[mx2s]

done