The current frame doesn't appear in stack traces in PHP 7

[joshuabenuck]

Description

PHP 7's zend_fetch_debug_backtrace() implementation differs in practice from PHP 5 by not including the current execution data as the first frame in the stack trace when the executor is in a user function.

This results in the user not getting a stack trace when an error occurs in the global scope:

<?php

$a = '';
echo $a['foo'];

The error is reported, but with a completely empty stack trace. Similarly, errors deep in large functions will be hard to trace because the current line number isn't included.

Steps to Reproduce

Create a file named new_relic_test.php with the following contents.

<?php
    require('LearnNewrelicTest.class.php');
    $learn = new LearnNewrelicTest();
    $learn->addMultipleCourse();
    ?>

Create a second file named LearnNewrelicTest.class.php with the following contents

<?php

    class LearnNewrelicTest {
        public function getCRMUserList() {
            $items = null;
            foreach($items as $item){
            }
        }
        public function addMultipleCourse() {
          $this->getCRMUserList();
        }
    }

Run the first php file using a a PHP 7.2 command line

$ php --version
    PHP 7.2.13 (cli) (built: Dec  7 2018 10:43:44) ( NTS )
    Copyright (c) 1997-2018 The PHP Group
    Zend Engine v3.2.0, Copyright (c) 1998-2018 Zend Technologies
        with Zend OPcache v7.2.13, Copyright (c) 1999-2018, by Zend Technologies
    $ php new_relic_test.php 

    Warning: Invalid argument supplied for foreach() in 
    /path/to/LearnNewrelicTest.class.php on line 6

Observe the contents of JSON posted to the error_event_data endpoint – specifically the key named stack_trace

Expected:

{"stack_trace":
      [
        " in LearnNewrelicTest::getCRMUserList called at \/path\/to\/LearnNewrelicTest.class.php (6)",      
        " in LearnNewrelicTest::getCRMUserList called at \/path\/to\/LearnNewrelicTest.class.php (10)",
        " in LearnNewrelicTest::addMultipleCourse called at \/path\/to\/new_relic_test.php (4)"
      ]
    }

Actual:

{"stack_trace":
      [   
        " in LearnNewrelicTest::getCRMUserList called at \/path\/to\/LearnNewrelicTest.class.php (10)",
        " in LearnNewrelicTest::addMultipleCourse called at \/path\/to\/new_relic_test.php (4)"
      ]
    }

i.e. the stack trace is missing the frame that actually points to the error the line is on.