Add comment explaining why isSuperTypeOf matching is limited to integer ranges

The conditional expression system intersects results from ALL matching
conditions. Using isSuperTypeOf broadly causes types like bool to match
both 'false' and 'bool' conditions simultaneously, producing *NEVER*
when their results conflict. Integer ranges (from count()) don't have
this problem because their conditions are non-overlapping.

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

Author: phpstan-bot

src/Analyser/MutatingScope.php

@@ -2155,6 +2155,18 @@ private function conditionalExpressionHolderMatches(ExpressionTypeHolder $specif
 		}
 
 		$conditionType = $condition->getType();
+
+		// Only use isSuperTypeOf for non-constant integer types (i.e. IntegerRangeType).
+		// This is needed for count()-in-variable patterns: when $count = count($a) creates
+		// a condition on int<1, max>, and $count is later narrowed to int<2, max> or 1,
+		// the subtype relationship correctly preserves the array narrowing.
+		//
+		// We cannot safely extend this to all types because filterBySpecifiedTypes()
+		// intersects results from ALL matching conditional expressions (line ~3251).
+		// For types like bool, isSuperTypeOf would match both a 'false' condition AND
+		// a 'bool' condition simultaneously, and intersecting their (potentially conflicting)
+		// results produces *NEVER*. Integer ranges don't have this problem because
+		// count() creates non-overlapping conditions (e.g. int<1, max> vs 0).
 		if (!$conditionType->isInteger()->yes() || $conditionType->isConstantScalarValue()->yes()) {
 			return false;
 		}