test coalesce with int ranges

tests/PHPStan/Analyser/nsrt/bug-14213.php

@@ -0,0 +1,102 @@
+<?php declare(strict_types = 1);
+
+namespace Bug14213;
+
+use function PHPStan\Testing\assertType;
+
+class HelloWorld
+{
+	public static function coalesce_nonsensical(): void
+	{
+		$x0 = $x1 = $x2 = null;
+
+		if (rand(0, 1)) {
+			$x0 = rand(0, 1);
+			$x1 = rand(2, 3);
+			$x2 = rand(4, 5);
+		}
+
+		// either all 3 variables are null, or all have a int-range value
+		$x = (
+			$x0 ??
+			$x1 ??
+			$x2
+		);
+
+		assertType('int<0, 1>|null', $x);
+	}
+
+	public static function coalesce_int_ranges(): void
+	{
+		$x0 = $x1 = $x2 = null;
+
+		if (rand(0, 1)) {
+			$x0 = rand(0, 1);
+		}
+		if (rand(0, 1)) {
+			$x1 = rand(2, 3);
+		}
+		if (rand(0, 1)) {
+			$x2 = rand(4, 5);
+		}
+
+		$x = (
+			$x0 ??
+			$x1 ??
+			$x2
+		);
+
+		assertType('int<0, 5>|null', $x);
+	}
+
+	public static function coalesce_int_range_after_maybe_defined(): void
+	{
+		$x0 = $x1 = $x2 = null;
+
+		if (rand(0, 1)) {
+			$maybeDefined = 10;
+		}
+		if (rand(0, 1)) {
+			$x0 = rand(0, 1);
+		}
+		if (rand(0, 1)) {
+			$x1 = rand(2, 3);
+		}
+		if (rand(0, 1)) {
+			$x2 = rand(4, 5);
+		}
+
+		$x = (
+			$maybeDefined ??
+			$x0 ??
+			$x1 ??
+			$x2
+		);
+
+		assertType('10|int<0, 5>|null', $x);
+	}
+
+	public static function coalesce_int_range_with_last_non_nullable(): void
+	{
+		$x0 = $x1 = null;
+		$x2 = 20;
+
+		if (rand(0, 1)) {
+			$x0 = rand(0, 1);
+		}
+		if (rand(0, 1)) {
+			$x1 = rand(2, 3);
+		}
+		if (rand(0, 1)) {
+			$x2 = rand(4, 5);
+		}
+
+		$x = (
+			$x0 ??
+			$x1 ??
+			$x2 // cannot be null
+		);
+
+		assertType('20|int<0, 5>', $x);
+	}
+}

tests/PHPStan/Rules/Variables/NullCoalesceRuleTest.php

@@ -352,4 +352,14 @@ public function testPr4372(): void
 		$this->analyse([__DIR__ . '/data/pr-4372-null-coalesce.php'], []);
 	}
 
+	public function testBug14213(): void
+	{
+		$this->analyse([__DIR__ . '/../../Analyser/nsrt/bug-14213.php'], [
+			[
+				'Variable $x1 on left side of ?? always exists and is always null.',
+				22,
+			],
+		]);
+	}
+
 }