Allow null for nl2br, striptags and format filters

Same as https://github.com/twigphp/Twig/pull/3617

src/Extension/CoreExtension.php

@@ -213,7 +213,7 @@ final class CoreExtension extends AbstractExtension
             // formatting filters
             new TwigFilter('date', 'twig_date_format_filter', ['needs_environment' => true]),
             new TwigFilter('date_modify', 'twig_date_modify_filter', ['needs_environment' => true]),
-            new TwigFilter('format', 'sprintf'),
+            new TwigFilter('format', 'twig_sprintf'),
             new TwigFilter('replace', 'twig_replace_filter'),
             new TwigFilter('number_format', 'twig_number_format_filter', ['needs_environment' => true]),
             new TwigFilter('abs', 'abs'),
@@ -229,9 +229,9 @@ final class CoreExtension extends AbstractExtension
             new TwigFilter('capitalize', 'twig_capitalize_string_filter', ['needs_environment' => true]),
             new TwigFilter('upper', 'twig_upper_filter', ['needs_environment' => true]),
             new TwigFilter('lower', 'twig_lower_filter', ['needs_environment' => true]),
-            new TwigFilter('striptags', 'strip_tags'),
+            new TwigFilter('striptags', 'twig_striptags'),
             new TwigFilter('trim', 'twig_trim_filter'),
-            new TwigFilter('nl2br', 'nl2br', ['pre_escape' => 'html', 'is_safe' => ['html']]),
+            new TwigFilter('nl2br', 'twig_nl2br', ['pre_escape' => 'html', 'is_safe' => ['html']]),
             new TwigFilter('spaceless', 'twig_spaceless', ['is_safe' => ['html']]),
 
             // array helpers
@@ -481,6 +481,19 @@ function twig_date_modify_filter(Environment $env, $date, $modifier)
     return $date->modify($modifier);
 }
 
+/**
+ * Returns a formatted string.
+ *
+ * @param string|null $format
+ * @param ...$values
+ *
+ * @return string
+ */
+function twig_sprintf($format, ...$values)
+{
+    return sprintf($format ?? '', ...$values);
+}
+
 /**
  * Converts an input to a \DateTime instance.
  *
@@ -996,6 +1009,18 @@ function twig_trim_filter($string, $characterMask = null, $side = 'both')
     }
 }
 
+/**
+ * Inserts HTML line breaks before all newlines in a string.
+ *
+ * @param string|null $string
+ *
+ * @return string
+ */
+function twig_nl2br($string)
+{
+    return nl2br($string ?? '');
+}
+
 /**
  * Removes whitespaces between HTML tags.
  *
@@ -1080,6 +1105,19 @@ function twig_lower_filter(Environment $env, $string)
     return mb_strtolower($string ?? '', $env->getCharset());
 }
 
+/**
+ * Strips HTML and PHP tags from a string.
+ *
+ * @param string|null $string
+ * @param string[]|string|null $string
+ *
+ * @return string
+ */
+function twig_striptags($string, $allowable_tags = null)
+{
+    return strip_tags($string ?? '', $allowable_tags);
+}
+
 /**
  * Returns a titlecased string.
  *

tests/Fixtures/filters/format.test

@@ -2,7 +2,11 @@
 "format" filter
 --TEMPLATE--
 {{ string|format(foo, 3) }}
+*{{ ""|format(foo, 3) }}*
+*{{ null|format(foo, 3) }}*
 --DATA--
 return ['string' => '%s/%d', 'foo' => 'bar']
 --EXPECT--
 bar/3
+**
+**

tests/Fixtures/filters/nl2br.test

@@ -3,6 +3,8 @@
 --TEMPLATE--
 {{ "I like Twig.\nYou will like it too.\n\nEverybody like it!"|nl2br }}
 {{ text|nl2br }}
+*{{ ''|nl2br }}*
+*{{ null|nl2br }}*
 --DATA--
 return ['text' => "If you have some <strong>HTML</strong>\nit will be escaped."]
 --EXPECT--
@@ -12,3 +14,5 @@ You will like it too.<br />
 Everybody like it!
 If you have some &lt;strong&gt;HTML&lt;/strong&gt;<br />
 it will be escaped.
+**
+**

tests/Fixtures/filters/striptags.test

@@ -0,0 +1,16 @@
+--TEST--
+"striptags" filter
+--TEMPLATE--
+{{ "Hello, <strong>World</strong>!"|striptags }}
+{{ text|striptags }}
+{{ text|striptags('<strong>')|raw }}
+*{{ ''|striptags }}*
+*{{ null|striptags }}*
+--DATA--
+return ['text' => "<p>Hello, <strong>World</strong>!</p>"]
+--EXPECT--
+Hello, World!
+Hello, World!
+Hello, <strong>World</strong>!
+**
+**

tests/IntegrationTest.php

@@ -229,7 +229,7 @@ class TwigTestExtension extends AbstractExtension
     {
         // not secure if $value contains html tags (not only entities)
         // don't use
-        return str_replace("\n", "$sep\n", $value);
+        return str_replace("\n", "$sep\n", $value ?? '');
     }
 
     public function dynamic_path($element, $item)