MultipartFormDataParser using UploadedFile does not work

[Nuffic]

What steps will reproduce the problem?

1. use yii\web\MultipartFormDataParser as a request parser
2. upload file using PATCH method
3. use UploadedFile to instanciate the file

What is the expected result?

When using UploadedFile::saveAs() file is saved into specified directory.

What do you get instead?

Since it uses php-s move_uploaded_file() or is_uploaded_file() which check if php itself dealt with uploaded file (which it didn't), file is not saved.

Additional info

yii\web\MultipartFormDataParser deals with $_FILES itself not php.

Q	A
Yii version	2.0.15.1

Relates to #6996 but is not the same.

[mihaivarga]

We attempted an upgrade from 2.0.14. For us this seems to be happening with latest #2.0.18 version using POST also. Any advice? File do not get saved, type not identified and files shows error 3 and validation trigger the file type missing. All works fine when we downgrade to 2.0.14.1.

[alexkart]

@Nuffic it's mentioned in the documentation https://www.yiiframework.com/doc/api/2.0/yii-web-multipartformdataparser

Note: although this parser fully emulates regular structure of the $_FILES, related temporary files, which are available via tmp_name key, will not be recognized by PHP as uploaded ones. Thus functions like is_uploaded_file() and move_uploaded_file() will fail on them. This also means yii\web\UploadedFile::saveAs() will fail as well.