Lowercase aggregate functions should not be inferred as mixed

Author: janedbal

Diff for: src/Type/Doctrine/Query/QueryResultTypeWalker.php

@@ -50,6 +50,7 @@
 use function serialize;
 use function sprintf;
 use function strtolower;
+use function strtoupper;
 use function unserialize;
 
 /**
@@ -930,7 +931,7 @@ public function walkSimpleSelectExpression($simpleSelectExpression): string
 	 */
 	public function walkAggregateExpression($aggExpression): string
 	{
-		switch ($aggExpression->functionName) {
+		switch (strtoupper($aggExpression->functionName)) {
 			case 'MAX':
 			case 'MIN':
 				$type = $this->unmarshalType(

Diff for: tests/Type/Doctrine/Query/QueryResultTypeWalkerTest.php

@@ -645,6 +645,19 @@ public function getTestData(): iterable
 			',
 		];
 
+		yield 'aggregate lowercase' => [
+			$this->constantArray([
+				[
+					new ConstantStringType('foo'),
+					TypeCombinator::addNull($this->numericStringified()),
+				],
+			]),
+			'
+				SELECT		avg(m.intColumn) as foo
+				FROM		QueryResult\Entities\Many m
+			',
+		];
+
 		yield 'aggregate with group by' => [
 			$this->constantArray([
 				[