Merging scopes in root scope - create maybe-existent variables from t…

…he other scope too

src/Analyser/MutatingScope.php

@@ -3353,6 +3353,14 @@ public function mergeWith(?self $otherScope): self
 
 				$ourVariableTypes[$name] = VariableTypeHolder::createMaybe(new MixedType());
 			}
+
+			foreach (array_keys($ourVariableTypes) as $name) {
+				if (array_key_exists($name, $theirVariableTypes)) {
+					continue;
+				}
+
+				$theirVariableTypes[$name] = VariableTypeHolder::createMaybe(new MixedType());
+			}
 		}
 
 		return $this->scopeFactory->create(

tests/PHPStan/Rules/DeadCode/UnreachableStatementRuleTest.php

@@ -80,4 +80,16 @@ public function testBugWithoutGitHubIssue1(bool $treatPhpDocTypesAsCertain): voi
 		$this->analyse([__DIR__ . '/data/bug-without-issue-1.php'], []);
 	}
 
+	public function testBug4070(): void
+	{
+		$this->treatPhpDocTypesAsCertain = true;
+		$this->analyse([__DIR__ . '/data/bug-4070.php'], []);
+	}
+
+	public function testBug4070Two(): void
+	{
+		$this->treatPhpDocTypesAsCertain = true;
+		$this->analyse([__DIR__ . '/data/bug-4070_2.php'], []);
+	}
+
 }

tests/PHPStan/Rules/DeadCode/data/bug-4070.php

@@ -0,0 +1,15 @@
+<?php
+
+namespace Bug4070;
+
+array_shift($argv);
+
+while ($argv) {
+	$arg = array_shift($argv);
+	if ($arg === 'foo') {
+		continue;
+	}
+	die();
+}
+
+echo "finished\n";

tests/PHPStan/Rules/DeadCode/data/bug-4070_2.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace Bug4070Two;
+
+function () {
+	array_shift($argv);
+
+	while ($argv) {
+		$arg = array_shift($argv);
+		if ($arg === 'foo') {
+			continue;
+		}
+		die();
+	}
+
+	echo "finished\n";
+};

tests/PHPStan/Rules/Functions/CallToFunctionParametersRuleTest.php

@@ -398,10 +398,6 @@ public function testUnpackOperator(): void
 	public function testFunctionWithNumericParameterThatCreatedByAddition(): void
 	{
 		$this->analyse([__DIR__ . '/data/function-with-int-parameter-that-created-by-addition.php'], [
-			[
-				'Parameter #1 $num of function dechex expects int, float|int given.',
-				9,
-			],
 			[
 				'Parameter #1 $num of function dechex expects int, float|int given.',
 				40,