Extend Gutenberg server rendering of templates and template parts for problem determination

[bobbingwide]

While analysing the problems I came across with Gutenberg 9.4.0 I developed an extension to template-part.php which added debug information visible in the front end.
It sandwiched the output for each template part in some debug <div class="WP_DEBUG"> tags
which contained the name of the template part.

I then wrote some naff CSS to enable the information to be viewed on the front end.

Requirements

• Formalise this solution for template parts
• Find a method to automatically produce front end information regarding the template file that's been selected
• Consider ways to easily turn the debug information on and off. e.g. Additional constant ( FSE_DEBUG), logged in admin user.

[bobbingwide]

Formalise solution for template parts

In Fizzie's template-part.php I changed the code to:

/**
  * Produce some visual aid to the theme developer, showing where the template starts and ends.
  *
  */
   if ( defined( 'FSE_DEBUG') && FSE_DEBUG ) {
       if (defined('WP_DEBUG') && WP_DEBUG) {
           $wrapped = "<div class=\"WP_DEBUG\">template part start: $slug</div>";
           $wrapped .= $content;
           $wrapped .= "<div class=\"WP_DEBUG END\">template part end: $slug</div>";
           $content = $wrapped;
           global $_wp_current_template_content;
           bw_trace2($_wp_current_template_content, "current template content", false, BW_TRACE_DEBUG);
       }
   }

Consider ways to easily turn the debug information on and off

I didn't bother to check if the user was logged in, nor if they had theme editing capability
just a check on FSE_DEBUG and WP_DEBUG.

Find a method to produce information for the template file

• I couldn't see any easy way to extend Gutenberg code.
• It'll have to be changed to fix issue Template hierarchy test cases #39 - Gutenberg issue 27177
• So I'll just do something else for the time being.

<div class="WP_DEBUG">front-page.html</div>

• Put a <div> with class="WP_DEBUG" into each template file.
• Style the div on the front end with CSS.
• Caveat: The Site editor can't handle classic blocks. But I'm not using the Site editor.

[bobbingwide]

Since I started creating the SB-debug-block plugin, where I encountered a couple of problems, and since I've not done much work on the internationalization (i18n) of templates and template parts I haven't really put much thought into the debuggability of templates and template parts.

So I may as well close this issue. The last commit was delivered in v0.1.1.