Treat func_get_args as using function params

src/Psalm/Internal/Analyzer/FunctionLikeAnalyzer.php

@@ -110,6 +110,13 @@ abstract class FunctionLikeAnalyzer extends SourceAnalyzer
      */
     public $inferred_has_mutation = false;
 
+    /**
+     * Holds param nodes for functions with func_get_args calls
+     *
+     * @var array<string, ControlFlowNode>
+     */
+    public $param_nodes = [];
+
     /**
      * @var FunctionLikeStorage
      */
@@ -1231,6 +1238,10 @@ abstract class FunctionLikeAnalyzer extends SourceAnalyzer
                     );
                 }
 
+                if ($storage->variadic) {
+                    $this->param_nodes += [$param_assignment->id => $param_assignment];
+                }
+
                 $var_type->parent_nodes += [$param_assignment->id => $param_assignment];
             }
 

src/Psalm/Internal/Analyzer/Statements/Expression/Call/ArgumentAnalyzer.php

@@ -285,6 +285,7 @@ class ArgumentAnalyzer
 
                 if (!$arg_type_param) {
                     $arg_type_param = Type::getMixed();
+                    $arg_type_param->parent_nodes = $arg_type->parent_nodes;
                 }
             }
 
@@ -1329,11 +1330,9 @@ class ArgumentAnalyzer
             $statements_analyzer->control_flow_graph->addSink($sink);
         }
 
-        if ($input_type->parent_nodes) {
+        foreach ($input_type->parent_nodes as $parent_node) {
-            foreach ($input_type->parent_nodes as $parent_node) {
+            $statements_analyzer->control_flow_graph->addNode($method_node);
-                $statements_analyzer->control_flow_graph->addNode($method_node);
+            $statements_analyzer->control_flow_graph->addPath($parent_node, $argument_value_node, 'arg');
-                $statements_analyzer->control_flow_graph->addPath($parent_node, $argument_value_node, 'arg');
-            }
         }
 
         if ($function_param->assert_untainted) {

src/Psalm/Internal/Analyzer/Statements/Expression/Call/FunctionCallAnalyzer.php

@@ -1515,6 +1515,22 @@ class FunctionCallAnalyzer extends CallAnalyzer
                     $statements_analyzer->node_data->setType($stmt, $arr_type);
                 }
             }
+        } elseif ($function_name->parts === ['func_get_args']) {
+            $source = $statements_analyzer->getSource();
+
+            if ($statements_analyzer->control_flow_graph
+                && $source instanceof \Psalm\Internal\Analyzer\FunctionLikeAnalyzer
+            ) {
+                if ($statements_analyzer->control_flow_graph instanceof \Psalm\Internal\Codebase\VariableUseGraph) {
+                    foreach ($source->param_nodes as $param_node) {
+                        $statements_analyzer->control_flow_graph->addPath(
+                            $param_node,
+                            new ControlFlowNode('variable-use', 'variable use', null),
+                            'variable-use'
+                        );
+                    }
+                }
+            }
         } elseif (strtolower($function_name->parts[0]) === 'var_dump'
             || strtolower($function_name->parts[0]) === 'shell_exec') {
             if (IssueBuffer::accepts(

tests/UnusedVariableTest.php

@@ -2174,6 +2174,19 @@ class UnusedVariableTest extends TestCase
                         print_r($source);
                     }'
             ],
+            'implicitSpread' => [
+                '<?php
+                    function validate(bool $b, bool $c) : void {
+                        $d = [$b, $c];
+                        print_r(...$d);
+                    }'
+            ],
+            'funcGetArgs' => [
+                '<?php
+                    function validate(bool $b, bool $c) : void {
+                        print_r(...func_get_args());
+                    }'
+            ],
         ];
     }