Introduce MissingDependency issue, separate from UndefinedClass

Ref #511

config.xsd

@@ -146,6 +146,7 @@
             <xs:element name="MissingClosureParamType" type="IssueHandlerType" minOccurs="0" />
             <xs:element name="MissingClosureReturnType" type="IssueHandlerType" minOccurs="0" />
             <xs:element name="MissingConstructor" type="IssueHandlerType" minOccurs="0" />
+            <xs:element name="MissingDependency" type="IssueHandlerType" minOccurs="0" />
             <xs:element name="MissingFile" type="IssueHandlerType" minOccurs="0" />
             <xs:element name="MissingParamType" type="IssueHandlerType" minOccurs="0" />
             <xs:element name="MissingPropertyType" type="IssueHandlerType" minOccurs="0" />

docs/issues.md

@@ -700,6 +700,19 @@ class A {
 }
 ```
 
+### MissingDependency
+
+Emitted when referencing a class that doesn’t exist
+
+```php
+/**
+ * @psalm-suppress UndefinedClass
+ */
+class A extends B {}
+
+$a = new A();
+```
+
 ### MissingDocblockType
 
 Emitted when a docblock is present, but the type is missing or badly formatted

src/Psalm/Checker/ClassLikeChecker.php

@@ -10,6 +10,7 @@ use Psalm\FileManipulation\FileManipulationBuffer;
 use Psalm\Issue\DuplicateClass;
 use Psalm\Issue\InaccessibleProperty;
 use Psalm\Issue\InvalidClass;
+use Psalm\Issue\MissingDependency;
 use Psalm\Issue\ReservedWord;
 use Psalm\Issue\UndefinedClass;
 use Psalm\IssueBuffer;
@@ -271,7 +272,7 @@ abstract class ClassLikeChecker extends SourceChecker implements StatementsSourc
 
         foreach ($class_storage->invalid_dependencies as $dependency_class_name) {
             if (IssueBuffer::accepts(
-                new UndefinedClass(
+                new MissingDependency(
                     $fq_class_name . ' depends on class or interface '
                         . $dependency_class_name . ' that does not exist',
                     $code_location

src/Psalm/Checker/Statements/Expression/Fetch/ArrayFetchChecker.php

@@ -84,6 +84,7 @@ class ArrayFetchChecker
 
         if ($keyed_array_var_id && isset($context->vars_in_scope[$keyed_array_var_id])) {
             $stmt->inferredType = clone $context->vars_in_scope[$keyed_array_var_id];
+
             return;
         }
 

src/Psalm/Issue/MissingDependency.php

@@ -0,0 +1,6 @@
+<?php
+namespace Psalm\Issue;
+
+class MissingDependency extends CodeIssue
+{
+}

tests/MethodCallTest.php

@@ -244,7 +244,7 @@ class MethodCallTest extends TestCase
                     class B extends A {}
 
                     $b = new B();',
-                'error_message' => 'UndefinedClass - src/somefile.php:7',
+                'error_message' => 'MissingDependency - src/somefile.php:7',
             ],
         ];
     }