base64_decode returns false only in strict mode

resources/functionMap.php

@@ -407,7 +407,8 @@
 'BadMethodCallException::getPrevious' => ['(?Throwable)|(?BadMethodCallException)'],
 'BadMethodCallException::getTrace' => ['array{function:string,line?:int,file?:string,class?:class-string,type?:\'::\'|\'->\',args?:mixed[],object?:object}'],
 'BadMethodCallException::getTraceAsString' => ['string'],
-'base64_decode' => ['string|false', 'str'=>'string', 'strict='=>'bool'],
+'base64_decode' => ['string', 'str'=>'string', 'strict='=>'false'],
+'base64_decode\'1' => ['string|false', 'str'=>'string', 'strict='=>'true'],
 'base64_encode' => ['string', 'str'=>'string'],
 'base_convert' => ['string', 'number'=>'string', 'frombase'=>'int', 'tobase'=>'int'],
 'basename' => ['string', 'path'=>'string', 'suffix='=>'string'],

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -1254,6 +1254,7 @@ public function dataFileAsserts(): iterable
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-9274.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/extract.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/image-size.php');
+		yield from $this->gatherAssertTypes(__DIR__ . '/data/base64_decode.php');
 	}
 
 	/**

tests/PHPStan/Analyser/data/base64_decode.php

@@ -0,0 +1,21 @@
+<?php declare(strict_types = 1);
+
+namespace Base64Decode;
+
+use function PHPStan\Testing\assertType;
+
+class Foo
+{
+
+	public function nonStrictMode(string $string): void
+	{
+		assertType('string', base64_decode($string));
+		assertType('string', base64_decode($string, false));
+	}
+
+	public function strictMode(string $string): void
+	{
+		assertType('string|false', base64_decode($string, true));
+	}
+
+}