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Bug #76361 Order of extending interfaces should not matter
Submitted: 2018-05-21 10:18 UTC Modified: 2018-05-23 12:43 UTC
Avg. Score:3.7 ± 0.5
Reproduced:2 of 2 (100.0%)
Same Version:0 (0.0%)
Same OS:0 (0.0%)
From: tobias dot nyholm at gmail dot com Assigned:
Status: Open Package: Scripting Engine problem
PHP Version: 7.2.5 OS:
Private report: No CVE-ID: None
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 [2018-05-21 10:18 UTC] tobias dot nyholm at gmail dot com
If an interface that extends two other interfaces, the order of those two other interfaces should not matter. 

I found this bug when I was testing solutions for PSR18 and HTTPlug. Here is an

This bug might be related to

Test script:


interface Response {}

interface Request {}

class RespImpl implements Response {}

class ReqImpl implements Request {}

interface Psr {
    public function sendRequest(Request $request): Response;

interface Httplug {
    public function sendRequest(Request $request);

//interface PsrBridge extends Psr, Httplug {} // does work
interface PsrBridge extends Httplug, Psr {} // does not work

class HttpClient implements PsrBridge {
    public function sendRequest(Request $request): Response {
        return new RespImpl();

$client = new HttpClient();
$response = $client->sendRequest(new ReqImpl());
echo $response instanceof Response ? 'OK' : 'Fail!';

Expected result:
I expect these two lines would give the same result: 

interface PsrBridge extends Psr, Httplug {}
interface PsrBridge extends Httplug, Psr {}

Actual result:
Fatal error: Declaration of Httplug::sendRequest(Request $request) must be compatible with Psr::sendRequest(Request $request): Response in /in/MMCL3 on line 22
Process exited with code 255.


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 [2018-05-23 12:43 UTC]
-Package: Unknown/Other Function +Package: Scripting Engine problem
 [2018-05-23 12:43 UTC]
It occurs to me that this is a duplicate of bug #67270.
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