[php-src] Issue #12800: Null Coalescing Operator + Ternary Operator Returns Wrong Result.

Issue: https://github.com/php/php-src/issues/12800 Author: 3Descape ### Description The following code: ```php <?php $a = "A"; echo("Null Coalescing Operator: "); echo($a ?? true ? "B" : "C"); echo("\nExpected result according to Documentation: "); if(isset($a)) { echo($a); } else { echo(true ? "B" : "C"); } ``` Resulted in this output: ``` Null Coalescing Operator: B Expected result according to Documentation: A ``` According to the equivalent code given in the [documentation](https://www.php.net/manual/en/language.operators.comparison.php#language.operators.comparison.coalesce) once whould expect the Null Coalescing Operator to return "A", since $a is set and not null. According to the equivalent code, the right hand side of the ?? operator (else branch in the equivalent code) should not be executed at all, when $a exists. The implementation of A ?? B currently seems to be equivalent to isset(A) ? A : B which, for A = $a and B = true ? "B" : "C", becomes isset($a) ? $a : true ? "B" : "C" which, [according to theleft-associativity prior to PHP 8.0.0](https://www.php.net/manual/en/language.operators.comparison.php#language.operators.comparison.ternary) is evaluated as (isset($a) ? $a : true) ? "B" : "C" = "B". Note: I also tested the null coalescing operator in php 8.2.10, I am just referecing php < 8.0 behaviour to speculate on the implementation problem. Though, it should be A ?? B = isset(A) ? A : (B) which, for A = $a and B = true ? "B" : "C", becomes isset($a) ? $a : (true ? "B" : "C)" = "A". ### PHP Version 8.2.10 ### Operating System _No response_