Add new issue conditional on config flag

config.xsd

@@ -137,6 +137,7 @@
             <xs:element name="InvalidScope" type="IssueHandlerType" minOccurs="0" />
             <xs:element name="InvalidStaticInvocation" type="IssueHandlerType" minOccurs="0" />
             <xs:element name="InvalidStaticVariable" type="IssueHandlerType" minOccurs="0" />
+            <xs:element name="InvalidStringClass" type="IssueHandlerType" minOccurs="0" />
             <xs:element name="InvalidThrow" type="IssueHandlerType" minOccurs="0" />
             <xs:element name="InvalidToString" type="IssueHandlerType" minOccurs="0" />
             <xs:element name="LessSpecificReturnStatement" type="IssueHandlerType" minOccurs="0" />

docs/issues.md

@@ -340,6 +340,16 @@ class Foo {}
 (new foo());
 ```
 
+### InvalidStringClass
+
+Emitted when you have `allowStringToStandInForClass="false"` in your config and you’re passing a string instead of calling a class directly
+
+```php
+class Foo {}
+$a = "Foo";
+new $a();
+```
+
 ### InvalidClone
 
 Emitted when trying to clone a value that's not cloneable

src/Psalm/Checker/Statements/Expression/Call/NewChecker.php

@@ -12,8 +12,9 @@ use Psalm\Context;
 use Psalm\Issue\AbstractInstantiation;
 use Psalm\Issue\DeprecatedClass;
 use Psalm\Issue\InterfaceInstantiation;
-use Psalm\Issue\InvalidClass;
+use Psalm\Issue\InvalidStringClass;
 use Psalm\Issue\TooManyArguments;
+use Psalm\Issue\UndefinedClass;
 use Psalm\IssueBuffer;
 use Psalm\Type;
 use Psalm\Type\Atomic\TNamedObject;
@@ -125,12 +126,26 @@ class NewChecker extends \Psalm\Checker\Statements\Expression\CallChecker
                         ) {
                             continue;
                         }
-                    } elseif ($lhs_type_part instanceof Type\Atomic\TMixed) {
+
+                        if (IssueBuffer::accepts(
+                            new InvalidStringClass(
+                                'String cannot be used as a class',
+                                new CodeLocation($statements_checker->getSource(), $stmt)
+                            ),
+                            $statements_checker->getSuppressedIssues()
+                        )) {
+                            // fall through
+                        }
+
+                        continue;
+                    }
+
+                    if ($lhs_type_part instanceof Type\Atomic\TMixed) {
                         continue;
                     }
 
                     if (IssueBuffer::accepts(
-                        new InvalidClass(
+                        new UndefinedClass(
                             'Type ' . $lhs_type_part . ' cannot be called as a class',
                             new CodeLocation($statements_checker->getSource(), $stmt)
                         ),

src/Psalm/Checker/Statements/Expression/Call/StaticCallChecker.php

@@ -11,8 +11,9 @@ use Psalm\Config;
 use Psalm\Context;
 use Psalm\FileManipulation\FileManipulationBuffer;
 use Psalm\Issue\DeprecatedClass;
-use Psalm\Issue\InvalidClass;
+use Psalm\Issue\InvalidStringClass;
 use Psalm\Issue\ParentNotFound;
+use Psalm\Issue\UndefinedClass;
 use Psalm\IssueBuffer;
 use Psalm\Type;
 use Psalm\Type\Atomic\TNamedObject;
@@ -205,12 +206,26 @@ class StaticCallChecker extends \Psalm\Checker\Statements\Expression\CallChecker
                     ) {
                         continue;
                     }
-                } elseif ($lhs_type_part instanceof Type\Atomic\TMixed) {
+
+                    if (IssueBuffer::accepts(
+                        new InvalidStringClass(
+                            'String cannot be used as a class',
+                            new CodeLocation($statements_checker->getSource(), $stmt)
+                        ),
+                        $statements_checker->getSuppressedIssues()
+                    )) {
+                        // fall through
+                    }
+
+                    continue;
+                }
+
+                if ($lhs_type_part instanceof Type\Atomic\TMixed) {
                     continue;
                 }
 
                 if (IssueBuffer::accepts(
-                    new InvalidClass(
+                    new UndefinedClass(
                         'Type ' . $lhs_type_part . ' cannot be called as a class',
                         new CodeLocation($statements_checker->getSource(), $stmt)
                     ),

src/Psalm/Issue/InvalidStringClass.php

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

tests/AnnotationTest.php

@@ -133,7 +133,7 @@ class AnnotationTest extends TestCase
 
     /**
      * @expectedException        \Psalm\Exception\CodeException
-     * @expectedExceptionMessage InvalidClass
+     * @expectedExceptionMessage InvalidStringClass
      *
      * @return                   void
      */
@@ -156,7 +156,7 @@ class AnnotationTest extends TestCase
 
     /**
      * @expectedException        \Psalm\Exception\CodeException
-     * @expectedExceptionMessage InvalidClass
+     * @expectedExceptionMessage InvalidStringClass
      *
      * @return                   void
      */

tests/DocumentationTest.php

@@ -148,6 +148,9 @@ class DocumentationTest extends TestCase
 
         foreach (self::getCodeBlocksFromDocs() as $issue_name => $blocks) {
             switch ($issue_name) {
+                case 'InvalidStringClass':
+                    continue 2;
+
                 case 'InvalidFalsableReturnType':
                     $ignored_issues = ['FalsableReturnStatement'];
                     break;

tests/MethodCallTest.php

@@ -271,13 +271,13 @@ class MethodCallTest extends TestCase
                 '<?php
                     $a = 5;
                     $a::bar();',
-                'error_message' => 'InvalidClass',
+                'error_message' => 'UndefinedClass',
             ],
             'intVarNewCall' => [
                 '<?php
                     $a = 5;
                     new $a();',
-                'error_message' => 'InvalidClass',
+                'error_message' => 'UndefinedClass',
             ],
         ];
     }