From 4f2a200b45e5f79a5d04894f5bf5ca972f60d5a2 Mon Sep 17 00:00:00 2001
From: Matthew Brown <github@muglug.com>
Date: Sat, 11 Nov 2017 14:53:35 -0500
Subject: [PATCH] Fix #283 - add more refined PossiblyUndefinedMethod check

---
 config.xsd                                    |  1 +
 .../Statements/Expression/CallChecker.php     | 60 ++++++++++++++-----
 src/Psalm/Issue/PossiblyUndefinedMethod.php   |  6 ++
 tests/TypeTest.php                            | 22 +++++++
 4 files changed, 73 insertions(+), 16 deletions(-)
 create mode 100644 src/Psalm/Issue/PossiblyUndefinedMethod.php

diff --git a/config.xsd b/config.xsd
index f32f93457..ba4e93f68 100644
--- a/config.xsd
+++ b/config.xsd
@@ -164,6 +164,7 @@
             <xs:element name="PossiblyNullPropertyAssignment" type="IssueHandlerType" minOccurs="0" />
             <xs:element name="PossiblyNullPropertyFetch" type="IssueHandlerType" minOccurs="0" />
             <xs:element name="PossiblyNullReference" type="IssueHandlerType" minOccurs="0" />
+            <xs:element name="PossiblyUndefinedMethod" type="IssueHandlerType" minOccurs="0" />
             <xs:element name="PossiblyUndefinedVariable" type="IssueHandlerType" minOccurs="0" />
             <xs:element name="PossiblyUnusedVariable" type="IssueHandlerType" minOccurs="0" />
             <xs:element name="PossiblyUnusedMethod" type="IssueHandlerType" minOccurs="0" />
diff --git a/src/Psalm/Checker/Statements/Expression/CallChecker.php b/src/Psalm/Checker/Statements/Expression/CallChecker.php
index 341a96d32..c9186e4d6 100644
--- a/src/Psalm/Checker/Statements/Expression/CallChecker.php
+++ b/src/Psalm/Checker/Statements/Expression/CallChecker.php
@@ -38,6 +38,7 @@ use Psalm\Issue\PossiblyInvalidArgument;
 use Psalm\Issue\PossiblyNullArgument;
 use Psalm\Issue\PossiblyNullFunctionCall;
 use Psalm\Issue\PossiblyNullReference;
+use Psalm\Issue\PossiblyUndefinedMethod;
 use Psalm\Issue\TooFewArguments;
 use Psalm\Issue\TooManyArguments;
 use Psalm\Issue\TypeCoercion;
@@ -760,6 +761,11 @@ class CallChecker
         $config = Config::getInstance();
         $project_checker = $statements_checker->getFileChecker()->project_checker;
 
+        $non_existent_method_ids = [];
+        $existent_method_ids = [];
+
+        $code_location = new CodeLocation($source, $stmt);
+
         if ($class_type && is_string($stmt->name)) {
             $return_type = null;
 
@@ -779,7 +785,7 @@ class CallChecker
                             if (IssueBuffer::accepts(
                                 new InvalidMethodCall(
                                     'Cannot call method ' . $stmt->name . ' on ' . $class_type . ' variable ' . $var_id,
-                                    new CodeLocation($statements_checker->getSource(), $stmt)
+                                    $code_location
                                 ),
                                 $statements_checker->getSuppressedIssues()
                             )) {
@@ -792,7 +798,7 @@ class CallChecker
                             if (IssueBuffer::accepts(
                                 new MixedMethodCall(
                                     'Cannot call method ' . $stmt->name . ' on a mixed variable ' . $var_id,
-                                    new CodeLocation($statements_checker->getSource(), $stmt)
+                                    $code_location
                                 ),
                                 $statements_checker->getSuppressedIssues()
                             )) {
@@ -829,7 +835,7 @@ class CallChecker
                     $does_class_exist = ClassLikeChecker::checkFullyQualifiedClassLikeName(
                         $project_checker,
                         $fq_class_name,
-                        new CodeLocation($statements_checker->getSource(), $stmt),
+                        $code_location,
                         $statements_checker->getSuppressedIssues()
                     );
                 }
@@ -842,7 +848,7 @@ class CallChecker
                     if (IssueBuffer::accepts(
                         new UndefinedMethod(
                             $fq_class_name . ' has no defined methods',
-                            new CodeLocation($statements_checker->getSource(), $stmt)
+                            $code_location
                         ),
                         $statements_checker->getSuppressedIssues()
                     )) {
@@ -893,17 +899,13 @@ class CallChecker
 
                 $cased_method_id = $fq_class_name . '::' . $stmt->name;
 
-                $does_method_exist = MethodChecker::checkMethodExists(
-                    $project_checker,
-                    $cased_method_id,
-                    new CodeLocation($statements_checker->getSource(), $stmt),
-                    $statements_checker->getSuppressedIssues()
-                );
-
-                if (!$does_method_exist) {
-                    return $does_method_exist;
+                if (!MethodChecker::methodExists($project_checker, $method_id, $code_location)) {
+                    $non_existent_method_ids[] = $method_id;
+                    continue;
                 }
 
+                $existent_method_ids[] = $method_id;
+
                 $class_template_params = null;
 
                 if ($stmt->var instanceof PhpParser\Node\Expr\Variable &&
@@ -945,7 +947,7 @@ class CallChecker
                     $stmt->args,
                     $class_template_params,
                     $context,
-                    new CodeLocation($source, $stmt),
+                    $code_location,
                     $statements_checker
                 ) === false) {
                     return false;
@@ -961,7 +963,7 @@ class CallChecker
                         $method_id,
                         $context->self,
                         $statements_checker->getSource(),
-                        new CodeLocation($source, $stmt),
+                        $code_location,
                         $statements_checker->getSuppressedIssues()
                     ) === false) {
                         return false;
@@ -970,7 +972,7 @@ class CallChecker
                     if (MethodChecker::checkMethodNotDeprecated(
                         $project_checker,
                         $method_id,
-                        new CodeLocation($source, $stmt),
+                        $code_location,
                         $statements_checker->getSuppressedIssues()
                     ) === false) {
                         return false;
@@ -1028,6 +1030,32 @@ class CallChecker
                 }
             }
 
+            if ($non_existent_method_ids) {
+                if ($existent_method_ids) {
+                    if (IssueBuffer::accepts(
+                        new PossiblyUndefinedMethod(
+                            'Method ' . $non_existent_method_ids[0] . ' does not exist',
+                            $code_location
+                        ),
+                        $statements_checker->getSuppressedIssues()
+                    )) {
+                        return false;
+                    }
+                } else {
+                    if (IssueBuffer::accepts(
+                        new UndefinedMethod(
+                            'Method ' . $non_existent_method_ids[0] . ' does not exist',
+                            $code_location
+                        ),
+                        $statements_checker->getSuppressedIssues()
+                    )) {
+                        return false;
+                    }
+                }
+
+                return null;
+            }
+
             $stmt->inferredType = $return_type;
         }
 
diff --git a/src/Psalm/Issue/PossiblyUndefinedMethod.php b/src/Psalm/Issue/PossiblyUndefinedMethod.php
new file mode 100644
index 000000000..3e6ed421e
--- /dev/null
+++ b/src/Psalm/Issue/PossiblyUndefinedMethod.php
@@ -0,0 +1,6 @@
+<?php
+namespace Psalm\Issue;
+
+class PossiblyUndefinedMethod extends CodeError
+{
+}
diff --git a/tests/TypeTest.php b/tests/TypeTest.php
index 7e476cf8b..0b94ecb89 100644
--- a/tests/TypeTest.php
+++ b/tests/TypeTest.php
@@ -1277,6 +1277,28 @@ class TypeTest extends TestCase
                     $a->fooBar();',
                 'error_message' => 'NullReference',
             ],
+            'possiblyUndefinedMethod' => [
+                '<?php
+                    class A {
+                        public function foo() : void {}
+                    }
+                    class B {
+                        public function other() : void {}
+                    }
+
+                    function a(bool $cond) : void {
+                        if ($cond) {
+                            $a = new A();
+                        } else {
+                            $a = new B();
+                        }
+
+                        if ($cond) {
+                            $a->foo();
+                        }
+                    }',
+                'error_message' => 'PossiblyUndefinedMethod',
+            ],
         ];
     }
 }