Add ability to detect invalid callable functions

src/Psalm/Checker/Statements/Expression/CallChecker.php

@@ -1759,7 +1759,8 @@ class CallChecker
                             $fleshed_out_type,
                             $cased_method_id,
                             $argument_offset,
-                            new CodeLocation($statements_checker->getSource(), $arg->value)
+                            new CodeLocation($statements_checker->getSource(), $arg->value),
+                            $arg->value
                         ) === false) {
                             return false;
                         }
@@ -2014,7 +2015,8 @@ class CallChecker
         Type\Union $param_type,
         $cased_method_id,
         $argument_offset,
-        CodeLocation $code_location
+        CodeLocation $code_location,
+        PhpParser\Node\Expr $input_expr = null
     ) {
         if ($param_type->isMixed()) {
             return null;
@@ -2151,6 +2153,34 @@ class CallChecker
             )) {
                 return false;
             }
+        } elseif ($input_expr instanceof PhpParser\Node\Scalar\String_) {
+            foreach ($param_type->types as $param_type_part) {
+                if ($param_type_part instanceof TCallable) {
+                    $function_name = $input_expr->value;
+
+                    if (strpos($function_name, '::') !== false) {
+                        if (MethodChecker::checkMethodExists(
+                                $project_checker,
+                                $function_name,
+                                $code_location,
+                                $statements_checker->getSuppressedIssues()
+                            ) === false
+                        ) {
+                            return false;
+                        }
+                    } else {
+                        if (self::checkFunctionExists(
+                                $project_checker,
+                                $statements_checker,
+                                $function_name,
+                                $code_location
+                            ) === false
+                        ) {
+                            return false;
+                        }
+                    }
+                }
+            }
         }
 
         return null;

src/Psalm/Visitor/DependencyFinderVisitor.php

@@ -398,7 +398,7 @@ class DependencyFinderVisitor extends PhpParser\NodeVisitorAbstract implements P
             $this->aliases = $this->file_aliases;
         } elseif ($node instanceof PhpParser\Node\Stmt\ClassLike) {
             if (!$this->fq_classlike_name) {
-                throw new \LogicException('$this->fq_classlike_name should bot be null');
+                throw new \LogicException('$this->fq_classlike_name should not be null');
             }
 
             $fq_classlike_name = $this->fq_classlike_name;
@@ -473,7 +473,7 @@ class DependencyFinderVisitor extends PhpParser\NodeVisitorAbstract implements P
             }
         } elseif ($stmt instanceof PhpParser\Node\Stmt\ClassMethod) {
             if (!$this->fq_classlike_name) {
-                throw new \LogicException('$this->fq_classlike_name should bot be null');
+                throw new \LogicException('$this->fq_classlike_name should not be null');
             }
 
             $fq_classlike_name = $this->fq_classlike_name;
@@ -978,7 +978,7 @@ class DependencyFinderVisitor extends PhpParser\NodeVisitorAbstract implements P
         Config $config
     ) {
         if (!$this->fq_classlike_name) {
-            throw new \LogicException('$this->fq_classlike_name should bot be null');
+            throw new \LogicException('$this->fq_classlike_name should not be null');
         }
 
         $comment = $stmt->getDocComment();

tests/ClosureTest.php

@@ -103,6 +103,24 @@ class ClosureTest extends TestCase
                     $take_string = function(string $s) : string { return $s; };
                     $take_string("string");',
             ],
+            'callableMethod' => [
+                '<?php
+                    class A {
+                        public static function bar(string $a) : string {
+                            return $a . "b";
+                        }
+                    }
+
+                    public function foo(callable $c) : void {}
+
+                    foo("A::bar");',
+            ],
+            'callableFunction' => [
+                '<?php
+                    function foo(callable $c) : void {}
+
+                    foo("trim");',
+            ],
         ];
     }
 
@@ -151,6 +169,26 @@ class ClosureTest extends TestCase
                 'error_message' => 'InvalidFunctionCall',
                 'error_levels' => ['UndefinedClass'],
             ],
+            'undefinedCallableMethod' => [
+                '<?php
+                    class A {
+                        public static function bar(string $a) : string {
+                            return $a . "b";
+                        }
+                    }
+
+                    public function foo(callable $c) : void {}
+
+                    foo("A::barr");',
+                'error_message' => 'UndefinedMethod',
+            ],
+            'undefinedCallableFunction' => [
+                '<?php
+                    function foo(callable $c) : void {}
+
+                    foo("trime");',
+                'error_message' => 'UndefinedFunction',
+            ],
             'possiblyNullFunctionCall' => [
                 '<?php
                     /**