Why shortcode @php() interfere with @php and @endphp

Question

I am looking for a reason why in blade files (Laravel) code with mixed @php() and @php ... @endphp fails, and works fine with consistent usage of those codes across the file. I've just learned that the hard way but can't find the reason.

Fails:

@php($foo = 'foo')
<h1>{{ $foo }}</h1>
@php
    $bar = $foo . 'bar';
@endphp
@for($i = 1; $i<10; $i++)
    <h2><b>{{ $i }}<b/>{{ $bar }}</h2>
@endfor

Works fine:

@php($foo = 'foo')
<h1>{{ $foo }}</h1>
@php($bar = $foo . 'bar');
@for($i = 1; $i<10; $i++)
    <h2><b>{{ $i }}<b/>{{ $bar }}</h2>
@endfor

Also works fine:

@php
    $foo = 'foo';
@endphp
<h1>{{ $foo }}</h1>
@php
    $bar = $foo . 'bar';
@endphp
@for($i = 1; $i<10; $i++)
    <h2><b>{{ $i }}<b/>{{ $bar }}</h2>
@endfor

An error

Answer 1

The issue in my view is the order of operations when processing @php blocks.

The relevant source code will first store uncompiled blocks before it actually compiles anything. Uncompiled blocks seem to be @php ... @endphp and @verbatim ... @endverbatim blocks. The code for @php is:

   protected function storePhpBlocks($value)
    {
        return preg_replace_callback('/(?<!@)@php(.*?)@endphp/s', function ($matches) {
            return $this->storeRawBlock("<?php{$matches[1]}?>");
        }, $value);
    }

So in your code block, the process of trying to store code between a @php ... @endphp everything between @php($foo = 'foo') and @endphp will be matched (which includes the 2nd @php tag) which will result in broken PHP code being stored.

Reading the docs I can see that while the syntax @php ... @endphp is documented, the alternative syntax @php(...) is not which makes me think that while the blade compiler implementation supports this syntax, it has not been documented (or not documented anymore) because it is problematic.