Only count HasOffsetValueType accessories for complexity limit

Instead of counting all union type members, only count union members
that contain HasOffsetValueType accessories. This more precisely
targets the source of exponential growth while avoiding false
positives on unions that are large for other reasons.

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

Author: 2 people

src/Analyser/MutatingScope.php

@@ -2700,7 +2700,18 @@ public function specifyExpressionType(Expr $expr, Type $type, Type $nativeType,
 						}
 					}
 
-					$tooComplex = $exprVarType instanceof UnionType && count($exprVarType->getTypes()) > self::ARRAY_DIM_FETCH_UNION_TYPE_LIMIT;
+					$hasOffsetAccessoryCount = 0;
+					if ($exprVarType instanceof UnionType) {
+						foreach ($exprVarType->getTypes() as $innerType) {
+							foreach (TypeUtils::getAccessoryTypes($innerType) as $accessoryType) {
+								if ($accessoryType instanceof HasOffsetValueType) {
+									$hasOffsetAccessoryCount++;
+									break;
+								}
+							}
+						}
+					}
+					$tooComplex = $hasOffsetAccessoryCount > self::ARRAY_DIM_FETCH_UNION_TYPE_LIMIT;
 					if (!$tooComplex && ($dimType instanceof ConstantIntegerType || $dimType instanceof ConstantStringType)) {
 						$varType = TypeCombinator::intersect(
 							$varType,