Change !isset to ??= assignment operator: multi-line case.

A Commit corresponding nearly to the patch 9B → . As said in #9 📌 Switch long-form single-line assign and null coalesce (= ??) to null coalesce assign operator (??=) Needs work this need review and comments.

Don't see anything to review?

Also if this is a spin off of the other ticket can it be noticed how come?

Also if comments can be copied so reviewers/committers don't have to jump between tickets to follow a conversation.

Mistakes exist. Still some work.

The MR faced obstructions from phpstan: 4 = 2x2 errors: 2 files,

 ------ --------------------------------------------------------------------------------------------- 
  Line   core/modules/views/src/Plugin/views/display/PathPluginBase.php                               
 ------ --------------------------------------------------------------------------------------------- 
         Ignored error pattern #^Variable \$access_plugin in isset\(\) always                         
         exists and is not nullable\.$# in path                                                       
         /builds/issue/drupal-3423310/core/modules/views/src/Plugin/views/display/PathPluginBase.php  
         was not matched in reported errors.                                                          
  199    Variable $access_plugin on left side of ??= always exists and is not                         
         nullable.                                                                                    
 ------ --------------------------------------------------------------------------------------------- 
 ------ --------------------------------------------------------------------------------------------------- 
  Line   core/modules/views_ui/tests/src/FunctionalJavascript/PreviewTest.php                               
 ------ --------------------------------------------------------------------------------------------------- 
         Ignored error pattern #^Variable \$message in isset\(\) always exists                              
         and is not nullable\.$# in path                                                                    
         /builds/issue/drupal-3423310/core/modules/views_ui/tests/src/FunctionalJavascript/PreviewTest.php  
         was not matched in reported errors.                                                                
  309    Variable $message on left side of ??= always exists and is not                                     
         nullable.                                                                                          
 ------ --------------------------------------------------------------------------------------------------- 
 [ERROR] Found 4 errors

The problem seems not the present code transformation but an other problem. To allow a MR we propose,
- to remove these 2 files from this MR,
- to create an other issue about these phpstan problems,
- to treat in an other issue the ??= code transformation of these 2 remaining files.

Mergeable.

Okay @smustgrave: MR is powerful, compare to patch. Lot of validation work is made by the machine. Now MR mergeable got, the human work needed is smaller.

Then, compared to the initial goal,

ideally a coding standards sniff we could enable to prevent this code from creeping back in.

all the cases are not considered here. Two sets are known missing: #8 📌 Use null coalescing assignment operator: multi-lines case. Needs work and #9 📌 Use null coalescing assignment operator: multi-lines case. Needs work .
#8 is not explicit enough about "generated files". That is some php files with header,

/**
 * This file was generated via php core/scripts/generate-proxy-class.php <*> <*>.
 */

I plan 2 other issues for them.

Do you know if there is a code sniffing rule we could enable that would prevent these from coming back?

The Needs Review Queue Bot → tested this issue. It no longer applies to Drupal core. Therefore, this issue status is now "Needs work".

This does not mean that the patch necessarily needs to be re-rolled or the MR rebased. Read the Issue Summary, the issue tags and the latest discussion here to determine what needs to be done.

Consult the Drupal Contributor Guide → to find step-by-step guides for working with issues.

As observed by @dpi for an other case 📌 Switch long-form single-line assign and null coalesce (= ??) to null coalesce assign operator (??=) Needs work , some files are missed. Since some directories was ignored.

A new commit, since a rebase was needed. 4 conflicts, in,

core/lib/Drupal/Core/Database/Query/Insert.php
core/lib/Drupal/Core/EventSubscriber/ConfigImportSubscriber.php
core/modules/workspaces/src/WorkspaceManager.php
core/tests/Drupal/KernelTests/Core/Cache/GenericCacheBackendUnitTestBase.php

MR mergeable. NR.

Two sets are voluntary ignored here,
- generator/generated files 📌 Change !isset to ??= assignment operator: generator and their generated files case. Needs review .
- 2 files with phpstan obstruction 📌 Use null coalescing assignment operator ??=: phpstan obstruction case. Closed: won't fix .

For a code sniff rule, this multi-line case is much more complicate than the uni-line case. Since several different configurations exist, and many should be exclude from this transformation: if else, if elseif, etc.

The sed command used has a rule to reach the good targets. Not perfect. Maybe the best is to use rector rule, as suggest by @dpi in #3418494-#23 📌 Switch long-form single-line assign and null coalesce (= ??) to null coalesce assign operator (??=) Needs work . However the rule doesn't exist (?).

Questions,
-1. Did the transformations done are right?
-2. Did some files are missed?
-3. Did some cases are missed?

Do you know if there is a code sniffing rule we could enable that would prevent these from coming back?

Okay @smustgrave, you mean a rule for phpcs... There is,
slevomat/coding-standard/SlevomatCodingStandard/Sniffs/ControlStructures/RequireNullCoalesceEqualOperatorSniff
but is missing in drupal/coder/coder_sniffer/Drupal/ruleset.xml. That is,
<rule ref="SlevomatCodingStandard.ControlStructures.RequireNullCoalesceEqualOperator" />
Maybe to be after,
<rule ref="SlevomatCodingStandard.ControlStructures.RequireNullCoalesceOperator" />

The Needs Review Queue Bot → tested this issue. It no longer applies to Drupal core. Therefore, this issue status is now "Needs work".

This does not mean that the patch necessarily needs to be re-rolled or the MR rebased. Read the Issue Summary, the issue tags and the latest discussion here to determine what needs to be done.

Consult the Drupal Contributor Guide → to find step-by-step guides for working with issues.

and ideally a coding standards sniff we could enable to prevent this code from creeping back in.

A coding standards sniff rule now ready for this multi-line case. And now case fixable with phpcbf. MR mergeable. Need review.

phpcs command used,
phpcs --standard=SlevomatCodingStandard --sniffs=SlevomatCodingStandard.ControlStructures.RequireNullCoalesceOperatorIsset --extensions=php,module,inc core
The file RequireNullCoalesceOperatorIssetSniff.php has to be in the right place: in slevomat/coding-standard/SlevomatCodingStandard/Sniffs/ControlStructures, in /home/.config/composer/vendor.

Better file...

On the coding standard decision #3436307: Change !isset to the null coalescing assignment operator ??= →