Move HasOffset type stripping from isValidVariance to generalizeInferredTemplateType

Instead of working around the equals check in TemplateTypeVariance::isValidVariance(),
strip HasOffsetValueType and HasOffsetType during template type generalization in
TemplateTypeHelper::generalizeInferredTemplateType(). This normalizes inferred
template types before they reach the invariance check, so equals() naturally
returns true without needing special handling.

Changing IntersectionType::equals() globally was investigated but breaks scope
tracking and type narrowing (introduces false positives in PHPStan self-analysis).
The generalization approach is more targeted: it only affects inferred template
type arguments for non-covariant templates, which is the correct normalization
point for this precision.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: phpstan-bot

src/Type/Generic/TemplateTypeHelper.php

@@ -3,8 +3,11 @@
 namespace PHPStan\Type\Generic;
 
 use PHPStan\Reflection\ParametersAcceptor;
+use PHPStan\Type\Accessory\HasOffsetType;
+use PHPStan\Type\Accessory\HasOffsetValueType;
 use PHPStan\Type\ErrorType;
 use PHPStan\Type\GeneralizePrecision;
+use PHPStan\Type\MixedType;
 use PHPStan\Type\NonAcceptingNeverType;
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeTraverser;
@@ -147,6 +150,14 @@ public static function generalizeInferredTemplateType(TemplateType $templateType
 			} elseif ($type->isConstantValue()->yes() && (!$templateType->getBound()->isScalar()->yes() || $isArrayKey)) {
 				$type = $type->generalize(GeneralizePrecision::templateArgument());
 			}
+
+			$type = TypeTraverser::map($type, static function (Type $type, callable $traverse): Type {
+				if ($type instanceof HasOffsetValueType || $type instanceof HasOffsetType) {
+					return new MixedType();
+				}
+
+				return $traverse($type);
+			});
 		}
 
 		return $type;

src/Type/Generic/TemplateTypeVariance.php

@@ -5,14 +5,11 @@
 use PHPStan\PhpDocParser\Ast\Type\GenericTypeNode;
 use PHPStan\ShouldNotHappenException;
 use PHPStan\TrinaryLogic;
-use PHPStan\Type\Accessory\HasOffsetType;
-use PHPStan\Type\Accessory\HasOffsetValueType;
 use PHPStan\Type\BenevolentUnionType;
 use PHPStan\Type\IsSuperTypeOfResult;
 use PHPStan\Type\MixedType;
 use PHPStan\Type\NeverType;
 use PHPStan\Type\Type;
-use PHPStan\Type\TypeTraverser;
 use function sprintf;
 
 /**
@@ -180,13 +177,6 @@ public function isValidVariance(TemplateType $templateType, Type $a, Type $b): I
 
 		if ($this->invariant()) {
 			$result = $a->equals($b);
-			if (!$result) {
-				$strippedA = self::stripHasOffsetTypes($a);
-				$strippedB = self::stripHasOffsetTypes($b);
-				if ($strippedA !== $a || $strippedB !== $b) {
-					$result = $strippedA->equals($strippedB);
-				}
-			}
 			$reasons = [];
 			if (!$result) {
 				if (
@@ -269,15 +259,4 @@ public function toPhpDocNodeVariance(): string
 		throw new ShouldNotHappenException();
 	}
 
-	private static function stripHasOffsetTypes(Type $type): Type
-	{
-		return TypeTraverser::map($type, static function (Type $type, callable $traverse): Type {
-			if ($type instanceof HasOffsetValueType || $type instanceof HasOffsetType) {
-				return new MixedType();
-			}
-
-			return $traverse($type);
-		});
-	}
-
 }