Add Section delta as extra data on filtered block definitions

I'm shocked that $delta is a string!

-  public function build(SectionStorageInterface $section_storage, $delta, $region) {
+  public function build(SectionStorageInterface $section_storage, int $delta, $region) {

This change fixes everything, but is invalid in PHP 5.

For now I guess we should do $delta = (int) $delta; with a code comment of some sort.

I debated when adding this hook about passing delta, but couldn't think of a use case where knowing the numeric delta would actually help.
Can you expand the Issue Summary to better explain the use case?

1. +++ b/core/modules/layout_builder/src/Controller/ChooseBlockController.php
   @@ -63,8 +63,12 @@ public function build(SectionStorageInterface $section_storage, $delta, $region)
   +    // Currently delta is passed as a string, so we'll explicitily convert it to a integer.
   

   Line exceeds 80 chars.

2. +++ b/core/modules/layout_builder/tests/src/Functional/LayoutBuilderTest.php
   @@ -351,6 +351,24 @@ public function testLayoutBuilderChooseBlocksAlter() {
   +    //Verify that Changed block is present on second section.
   

   Missing space at start of comment.

Other than that, this patch looks great! Works perfectly to allow me to filter the available blocks in my layouts.

I still can't personally envision using the specific delta, especially for anything other than $delta===0.
But there's nothing wrong with adding this, and if it's useful for others, might as well!

+++ b/core/modules/layout_builder/src/Controller/ChooseBlockController.php
@@ -63,8 +63,13 @@ public function build(SectionStorageInterface $section_storage, $delta, $region)
+    // Currently delta is passed as a string, so we'll explicitily convert it
+    // to a integer.
+    $delta = (int) $delta;

Explicitly is misspelled. Can we get an @todo for an issue to remove this cast?

Looks great, just a minor doc nit

1. +++ b/core/modules/layout_builder/src/Controller/ChooseBlockController.php
   @@ -63,8 +63,14 @@ public function build(SectionStorageInterface $section_storage, $delta, $region)
   +    // Currently delta is passed as a string, so we'll explicitly convert it
   +    // to a integer.
   +    // @TODO Fix in https://www.drupal.org/project/drupal/issues/2984509
   

   Can you rewrite this to:

       // @todo Explicitly cast delta to an integer, remove this in
       //   https://www.drupal.org/project/drupal/issues/2984509.
   

   (note the lowercase todo, the indent for the second line, and the trailing period)

2. +++ b/core/modules/layout_builder/tests/modules/layout_builder_test/layout_builder_test.module
   @@ -26,4 +31,5 @@ function layout_builder_test_plugin_filter_block__layout_builder_alter(array &$d
      }
   +
    }
   

   Extra blank line

Since these were minor changes, doing it myself and RTBCing.

Committed 0c3ea72 and pushed to 8.6.x. Thanks!

The patch committed only partially resolved this issue (it addressed non-inline blocks, but did not address inline blocks). I have provided a follow-up patch in #3038981: Inline blocks missing section delta extra data on filtered block definitions

Retroactively tagging