Invalidate count($array) after array_shift()

Author: ondrejmirtes

src/Analyser/NodeScopeResolver.php

@@ -1616,7 +1616,9 @@ function (MutatingScope $scope) use ($expr, $nodeCallback, $context): Expression
 			) {
 				$arrayArg = $expr->args[0]->value;
 				$constantArrays = TypeUtils::getConstantArrays($scope->getType($arrayArg));
-				$scope = $scope->invalidateExpression($arrayArg);
+				$scope = $scope->invalidateExpression($arrayArg)
+					->invalidateExpression(new FuncCall(new Name\FullyQualified('count'), [$expr->args[0]]))
+					->invalidateExpression(new FuncCall(new Name('count'), [$expr->args[0]]));
 				if (count($constantArrays) > 0) {
 					$resultArrayTypes = [];
 

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -10832,6 +10832,11 @@ public function dataBug2927(): array
 		return $this->gatherAssertTypes(__DIR__ . '/data/bug-2927.php');
 	}
 
+	public function dataBug4558(): array
+	{
+		return $this->gatherAssertTypes(__DIR__ . '/data/bug-4558.php');
+	}
+
 	/**
 	 * @param string $file
 	 * @return array<string, mixed[]>
@@ -11060,6 +11065,7 @@ private function gatherAssertTypes(string $file): array
 	 * @dataProvider dataBug1897
 	 * @dataProvider dataBug1801
 	 * @dataProvider dataBug2927
+	 * @dataProvider dataBug4558
 	 * @param string $assertType
 	 * @param string $file
 	 * @param mixed ...$args

tests/PHPStan/Analyser/data/bug-4558.php

@@ -0,0 +1,50 @@
+<?php
+
+namespace Bug4558;
+
+use DateTime;
+use function PHPStan\Analyser\assertType;
+
+class HelloWorld
+{
+	/**
+	 * @var DateTime[]
+	 */
+	private array $suggestions = [];
+
+	public function sayHello(): ?DateTime
+	{
+		while (count($this->suggestions) > 0) {
+			assertType('array<DateTime>&nonEmpty', $this->suggestions);
+			assertType('int<1, max>', count($this->suggestions));
+			$try = array_shift($this->suggestions);
+
+			assertType('array<DateTime>', $this->suggestions);
+			assertType('int<0, max>', count($this->suggestions));
+
+			if (rand(0, 1)) {
+				return $try;
+			}
+
+			assertType('array<DateTime>', $this->suggestions);
+			assertType('int<0, max>', count($this->suggestions));
+
+			// we might be out of suggested days, so load some more
+			if (count($this->suggestions) === 0) {
+				assertType('array()', $this->suggestions);
+				assertType('0', count($this->suggestions));
+				$this->createSuggestions();
+			}
+
+			assertType('array<DateTime>', $this->suggestions);
+			assertType('int<0, max>', count($this->suggestions));
+		}
+
+		return null;
+	}
+
+	private function createSuggestions(): void
+	{
+		$this->suggestions[] = new DateTime;
+	}
+}