Bleeding edge - rule to disallow loose comparisons

Author: nagmat84

rules.neon

@@ -52,6 +52,10 @@ rules:
 	- PHPStan\Rules\VariableVariables\VariableStaticPropertyFetchRule
 	- PHPStan\Rules\VariableVariables\VariableVariablesRule
 
+conditionalTags:
+	PHPStan\Rules\DisallowedConstructs\DisallowedLooseComparisonRule:
+		phpstan.rules.rule: %featureToggles.bleedingEdge%
+
 services:
 	-
 		class: PHPStan\Rules\BooleansInConditions\BooleanRuleHelper
@@ -71,3 +75,6 @@ services:
 			universalObjectCratesClasses: %universalObjectCratesClasses%
 		tags:
 			- phpstan.rules.rule
+
+	-
+		class: PHPStan\Rules\DisallowedConstructs\DisallowedLooseComparisonRule

src/Rules/DisallowedConstructs/DisallowedLooseComparisonRule.php

@@ -0,0 +1,44 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\DisallowedConstructs;
+
+use PhpParser\Node;
+use PhpParser\Node\Expr\BinaryOp;
+use PhpParser\Node\Expr\BinaryOp\Equal;
+use PhpParser\Node\Expr\BinaryOp\NotEqual;
+use PHPStan\Analyser\Scope;
+use PHPStan\Rules\Rule;
+use PHPStan\Rules\RuleErrorBuilder;
+
+/**
+ * @implements Rule<BinaryOp>
+ */
+class DisallowedLooseComparisonRule implements Rule
+{
+
+	public function getNodeType(): string
+	{
+		return BinaryOp::class;
+	}
+
+	public function processNode(Node $node, Scope $scope): array
+	{
+		if ($node instanceof Equal) {
+			return [
+				RuleErrorBuilder::message(
+					'Loose comparison via "==" is not allowed.'
+				)->tip('Use strict comparison via "===" instead.')->build(),
+			];
+		}
+		if ($node instanceof NotEqual) {
+			return [
+				RuleErrorBuilder::message(
+					'Loose comparison via "!=" is not allowed.'
+				)->tip('Use strict comparison via "!==" instead.')->build(),
+			];
+		}
+
+		return [];
+	}
+
+}

tests/Rules/DisallowedConstructs/DisallowedLooseComparisonRuleTest.php

@@ -0,0 +1,35 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\DisallowedConstructs;
+
+use PHPStan\Rules\Rule;
+use PHPStan\Testing\RuleTestCase;
+
+/**
+ * @extends RuleTestCase<DisallowedLooseComparisonRule>
+ */
+class DisallowedLooseComparisonRuleTest extends RuleTestCase
+{
+
+	protected function getRule(): Rule
+	{
+		return new DisallowedLooseComparisonRule();
+	}
+
+	public function testRule(): void
+	{
+		$this->analyse([__DIR__ . '/data/weak-comparison.php'], [
+			[
+				'Loose comparison via "==" is not allowed.',
+				3,
+				'Use strict comparison via "===" instead.',
+			],
+			[
+				'Loose comparison via "!=" is not allowed.',
+				5,
+				'Use strict comparison via "!==" instead.',
+			],
+		]);
+	}
+
+}

tests/Rules/DisallowedConstructs/data/weak-comparison.php

@@ -0,0 +1,6 @@
+<?php
+
+$bool1 = 123 == 456;
+$bool2 = 123 === 456;
+$bool3 = 123 != 456;
+$bool4 = 123 !== 456;