Main page content block is required

There's another issue for this somewhere, however I can't find it now. Either way this is just a normal bug, not major.

The patch provided works as it should.

Sidenote:
What about the sites that want to take full control of the blocks using the Context module?
Should they be able to disable the main content block from the block admin page?

Usually I disable all of the blocks when building the site (when this bug still existed) and then create a global Context that puts the main content in its place. But now that I tried to disable the main content block with this bug (and without Context), the content seems to always stay in the content area (which is really good if you don't have an admin theme and you'd disable your main content block). I think this is how it's supposed to work?
Sorry for getting maybe a bit off-rails here.

main_content_block_required.patch queued for re-testing.

I think #687686: Prevent hiding the Content Block on particular pages is the duplicate issue catch was referring too.

Main page content block is required

where this assumption comes from?

git apply ~/patches/main_content_block_required_0.patch
error: patch failed: core/modules/block/block.admin.inc:173
error: core/modules/block/block.admin.inc: patch does not apply

The validation should now be moved into BlockListController.

Re-rolled

Block naming changed a bit in that form, so I made changes reflected on interdiff.
Also, changed error message to make it more clear.

+++ b/core/modules/block/lib/Drupal/block/BlockListController.php
@@ -391,7 +391,10 @@ public function getOperations(EntityInterface $entity) {
+      form_set_error('blocks][' . $content, t('Main system content block needs to be placed in some region.'));

Should this be "Main page content block..."

Other than that, looks ready to go.

Text changed

Attached new patch with tests added.

14: main_content_block_required-14.patch queued for re-testing.

Green!

1. +++ b/core/modules/block/lib/Drupal/block/Tests/BlockUiTest.php
   @@ -117,6 +130,21 @@ function testBlockAdminUiPage() {
   +   * Tests that the main page content block needs to be assigned in some region.
   

   "needs to be assigned to a region."

2. +++ b/core/modules/block/lib/Drupal/block/Tests/BlockUiTest.php
   @@ -117,6 +130,21 @@ function testBlockAdminUiPage() {
   +    $this->assertText(t('Main page content block needs to be placed in some region.'), 'Failed to disable main page content block.');
   

   Should be: "placed in a region"

3. +++ b/core/modules/block/lib/Drupal/block/Tests/BlockUiTest.php
   @@ -117,6 +130,21 @@ function testBlockAdminUiPage() {
   +    // Try to set main page content block in main content region.
   

   should be "Try to set main page content block in the content region."

4. +++ b/core/modules/block/lib/Drupal/block/Tests/BlockUiTest.php
   @@ -117,6 +130,21 @@ function testBlockAdminUiPage() {
   +    $this->assertText(t('The block settings have been updated.'), 'Main page content block successfully moved to Content region.');
   

   no capital on "Content"

Sorry, some nitpicking text remarks!

Changed

Test completed

Looks good to me.

19: main_content_block_required-19.patch queued for re-testing.

19: main_content_block_required-19.patch queued for re-testing.

Re-roll.

26: drupal_1380858_26.patch queued for re-testing.

Was previously RTBC so setting back.

26: drupal_1380858_26.patch queued for re-testing.

+++ b/core/modules/block/lib/Drupal/block/BlockListController.php
@@ -396,7 +396,10 @@ public function getOperations(EntityInterface $entity) {
+      form_set_error('blocks][' . $content, t('Main page content block needs to be placed in a region.'));

This should at least be:

\Drupal::service('form_builder')->setErrorByName()

And we should probably inject the form_builder service.

This needs an issue summary update. In particular, what is the proposed resolution?

And an updated patch for 9.3.x

Forgot to add tag.

I know that usually the newer issue should be closed as a duplicate, but in this case #2546590: Main content block shows up on page, even if hidden has much more, and much more recent, activity so I'm going to close this one to prevent possibly working on two different approaches. I will move credit there for contributors to this issue.