changed false to null to allow for type hinting

src/Environment.php

@@ -781,18 +781,9 @@ class Environment
     }
 
     /**
-     * Get a filter by name.
-     *
-     * Subclasses may override this method and load filters differently;
-     * so no list of filters is available.
-     *
-     * @param string $name The filter name
-     *
-     * @return TwigFilter|false
-     *
      * @internal
      */
-    public function getFilter($name)
+    public function getFilter(string $name): ?TwigFilter
     {
         return $this->extensionSet->getFilter($name);
     }
@@ -836,15 +827,9 @@ class Environment
     }
 
     /**
-     * Gets a test by name.
-     *
-     * @param string $name The test name
-     *
-     * @return TwigTest|false
-     *
      * @internal
      */
-    public function getTest($name)
+    public function getTest(string $name): ?TwigTest
     {
         return $this->extensionSet->getTest($name);
     }
@@ -855,18 +840,9 @@ class Environment
     }
 
     /**
-     * Get a function by name.
-     *
-     * Subclasses may override this method and load functions differently;
-     * so no list of functions is available.
-     *
-     * @param string $name function name
-     *
-     * @return TwigFunction|false
-     *
      * @internal
      */
-    public function getFunction($name)
+    public function getFunction(string $name): ?TwigFunction
     {
         return $this->extensionSet->getFunction($name);
     }

src/ExpressionParser.php

@@ -668,7 +668,7 @@ class ExpressionParser
 
     private function getFunctionNodeClass(string $name, int $line): string
     {
-        if (false === $function = $this->env->getFunction($name)) {
+        if (!$function = $this->env->getFunction($name)) {
             $e = new SyntaxError(sprintf('Unknown "%s" function.', $name), $line, $this->parser->getStream()->getSourceContext());
             $e->addSuggestions($name, array_keys($this->env->getFunctions()));
 
@@ -694,7 +694,7 @@ class ExpressionParser
 
     private function getFilterNodeClass(string $name, int $line): string
     {
-        if (false === $filter = $this->env->getFilter($name)) {
+        if (!$filter = $this->env->getFilter($name)) {
             $e = new SyntaxError(sprintf('Unknown "%s" filter.', $name), $line, $this->parser->getStream()->getSourceContext());
             $e->addSuggestions($name, array_keys($this->env->getFilters()));
 

src/ExtensionSet.php

@@ -175,10 +175,7 @@ final class ExtensionSet
         return $this->functions;
     }
 
-    /**
-     * @return TwigFunction|false
-     */
-    public function getFunction(string $name)
+    public function getFunction(string $name): ?TwigFunction
     {
         if (!$this->initialized) {
             $this->initExtensions();
@@ -205,7 +202,7 @@ final class ExtensionSet
             }
         }
 
-        return false;
+        return null;
     }
 
     public function registerUndefinedFunctionCallback(callable $callable)
@@ -234,10 +231,7 @@ final class ExtensionSet
         return $this->filters;
     }
 
-    /**
-     * @return TwigFilter|false
-     */
-    public function getFilter(string $name)
+    public function getFilter(string $name): ?TwigFilter
     {
         if (!$this->initialized) {
             $this->initExtensions();
@@ -264,7 +258,7 @@ final class ExtensionSet
             }
         }
 
-        return false;
+        return null;
     }
 
     public function registerUndefinedFilterCallback(callable $callable)
@@ -362,10 +356,7 @@ final class ExtensionSet
         return $this->tests;
     }
 
-    /**
-     * @return TwigTest|false
-     */
-    public function getTest(string $name)
+    public function getTest(string $name): ?TwigTest
     {
         if (!$this->initialized) {
             $this->initExtensions();
@@ -388,7 +379,7 @@ final class ExtensionSet
             }
         }
 
-        return false;
+        return null;
     }
 
     public function getUnaryOperators(): array

src/NodeVisitor/SafeAnalysisNodeVisitor.php

@@ -95,7 +95,7 @@ final class SafeAnalysisNodeVisitor extends AbstractNodeVisitor
             // filter expression is safe when the filter is safe
             $name = $node->getNode('filter')->getAttribute('value');
             $args = $node->getNode('arguments');
-            if (false !== $filter = $env->getFilter($name)) {
+            if ($filter = $env->getFilter($name)) {
                 $safe = $filter->getSafe($args);
                 if (null === $safe) {
                     $safe = $this->intersectSafe($this->getSafe($node->getNode('node')), $filter->getPreservesSafety());
@@ -108,8 +108,7 @@ final class SafeAnalysisNodeVisitor extends AbstractNodeVisitor
             // function expression is safe when the function is safe
             $name = $node->getAttribute('name');
             $args = $node->getNode('arguments');
-            $function = $env->getFunction($name);
-            if (false !== $function) {
+            if ($function = $env->getFunction($name)) {
                 $this->setSafe($node, $function->getSafe($args));
             } else {
                 $this->setSafe($node, []);