Build/Test Tools: Add phpstan-strict-rules and enable rules core complies with

composer.json

@@ -54,6 +54,7 @@
 		"phpcompatibility/phpcompatibility-wp": "~2.1.3",
 		"phpstan/phpstan": "2.3.4",
 		"phpstan/phpstan-phpunit": "2.1.1",
+		"phpstan/phpstan-strict-rules": "2.1.1",
 		"yoast/phpunit-polyfills": "^1.1.0"
 	},
 	"config": {

phpstan.neon.dist

@@ -1,6 +1,8 @@
 # PHPStan configuration for WordPress Core.
 #
-# To overload this configuration, copy this file to phpstan.neon and adjust as needed.
+# To override this configuration, create a phpstan.neon which includes this file and adjusts
+# its parameters as needed, rather than copying it, so that the copy does not go stale. See
+# tests/phpstan/README.md for examples.
 #
 # https://phpstan.org/config-reference
 
@@ -58,11 +60,27 @@ includes:
 	- tests/phpstan/baselines/variable.undefined.neon
 	# phpstan:baselines end
 
+# Rules from phpstan-strict-rules which core already complies with, or which enforce the
+# WordPress Coding Standards. The others are not enabled until the code complies with them,
+# but they can be enabled in a local phpstan.neon to work toward that. See
+# tests/phpstan/README.md.
+#
+# These are registered individually, rather than by including phpstan-strict-rules' rules.neon
+# with only these enabled, because that file also makes several PHPStan parameters stricter
+# even when its rules are disabled.
+# https://github.com/phpstan/phpstan-strict-rules
+rules:
+	- PHPStan\Rules\DisallowedConstructs\DisallowedBacktickRule
+	- PHPStan\Rules\DisallowedConstructs\DisallowedShortTernaryRule
+	- PHPStan\Rules\Functions\ClosureUsesThisRule
+	- PHPStan\Rules\Methods\WrongCaseOfInheritedMethodRule
+
 parameters:
 	# https://phpstan.org/user-guide/rule-levels
 	level: 5
 	reportUnmatchedIgnoredErrors: true
 
+
 	# The following ignored errors are not intended to be fixed, as distinct from the baselines
 	# included above.
 	#

tests/phpstan/HashNotationVisitor.php

@@ -484,7 +484,12 @@ private function split_tags( string $text ): array {
 		$tags    = array();
 		$current = null;
 
-		foreach ( preg_split( '#\R#', (string) $body ) ?: array() as $line ) {
+		$lines = preg_split( '#\R#', (string) $body );
+		if ( false === $lines ) {
+			$lines = array();
+		}
+
+		foreach ( $lines as $line ) {
 			$line = (string) preg_replace( '#^\s*\* ?#', '', $line, 1 );
 
 			if ( preg_match( '#^@([a-zA-Z][a-zA-Z0-9_-]*)[ \t]*(.*)$#', $line, $matches ) === 1 ) {

tests/phpstan/README.md

@@ -4,7 +4,7 @@ PHPStan is a static analysis tool for PHP that checks your code for errors witho
 
 ## Running the tests
 
-PHPStan requires PHP and Composer dependencies to be installed.
+PHPStan requires PHP and Composer dependencies to be installed. Since there is no `composer.lock`, run `composer update` after pulling changes to `composer.json`, such as the addition of a PHPStan extension, or PHPStan will fail to load the configuration.
 
 If you don't already have an environment ready, you can set one up by following [these instructions](https://github.com/WordPress/wordpress-develop/blob/master/README.md).
 
@@ -54,9 +54,55 @@ Some errors cannot be ignored, and so cannot be reported as warnings either. The
 
 ## The PHPStan configuration
 
-The PHPStan configuration file is located at [`phpstan.neon.dist`](../../phpstan.neon.dist).
+The PHPStan configuration file is located at [`phpstan.neon.dist`](../../phpstan.neon.dist). It sets the standards the code is held to: the rule level, the baselines, the errors ignored as not actionable, and the [strict rules](#strict-rules) enabled. It includes [`base.neon`](base.neon), which configures what PHPStan needs to know to analyze the codebase at all, such as the [WordPress-specific extensions](#wordpress-specific-extensions), the paths analyzed, and the supported PHP versions.
 
-You can create a local copy at `phpstan.neon` to override the default configuration.
+To override the default configuration, create a `phpstan.neon` file in the repository root, which PHPStan reads in place of `phpstan.neon.dist`. Include `phpstan.neon.dist` in it rather than copying it, so the override only states what it changes and keeps up with changes to the default configuration. For example, to analyze at a stricter rule level:
+
+```neon
+includes:
+	- phpstan.neon.dist
+
+parameters:
+	level: 10
+```
+
+### Strict rules
+
+`phpstan.neon.dist` enables only the rules from [phpstan-strict-rules](https://github.com/phpstan/phpstan-strict-rules) which the code already complies with, registering each one individually. It does not include the package's `rules.neon`, since that file also makes several PHPStan parameters stricter, such as `checkDynamicProperties` and `reportMaybesInMethodSignatures`, even when its rules are disabled.
+
+To work toward complying with more of them, include `rules.neon` in your `phpstan.neon`. It enables every rule and makes those parameters stricter, unless `strictRules.allRules` is set to `false`, in which case only the rules set to `true` are enabled but the parameters are still made stricter. Either way, disable the rules `phpstan.neon.dist` already registers, or each error they report is reported twice:
+
+```neon
+includes:
+	- phpstan.neon.dist
+	- vendor/phpstan/phpstan-strict-rules/rules.neon
+
+parameters:
+	strictRules:
+		allRules: false
+		disallowedLooseComparison: true
+		overwriteVariablesWithLoop: true
+
+		# Already registered in phpstan.neon.dist.
+		disallowedBacktick: false
+		disallowedShortTernary: false
+		closureUsesThis: false
+		matchingInheritedMethodNames: false
+```
+
+The rules for `while` and `do`-`while` conditions are only enabled with [bleeding edge](https://phpstan.org/blog/what-is-bleeding-edge) (as are those for unary `+` and `-` operands), so `booleansInConditions: true` alone does not cover loops. Set `booleansInLoopConditions: true` to enable them without it.
+
+### Seeing every error
+
+The baselines and other ignored errors cannot be removed by leaving out an include, but a key ending in `!` replaces the value it would otherwise be merged with. So to see every error, including those the baselines suppress:
+
+```neon
+includes:
+	- phpstan.neon.dist
+
+parameters:
+	ignoreErrors!: []
+```
 
 For more information about configuring PHPStan, see the [PHPStan documentation's Config reference](https://phpstan.org/config-reference).
 

tests/phpstan/base.neon

@@ -1,6 +1,12 @@
 # Base PHPStan configuration for WordPress Core.
 #
-# This is kept separate from the main PHPStan configuration file to allow for easy overloading while baseline errors are being fixed.
+# This holds what PHPStan needs to know to analyze the WordPress codebase: the extensions for
+# WordPress-specific conventions, the paths analyzed and excluded, the supported PHP versions,
+# and the constants whose values vary. It rarely changes.
+#
+# The standards the code is held to, which are the rule level, the baselines, the errors
+# ignored as not actionable, and the strict rules enabled, are in phpstan.neon.dist instead,
+# so they can be read and reviewed apart from all of this.
 #
 # https://phpstan.org/config-reference