Add error for promoted property usage pre-PHP 8

src/Psalm/Internal/PhpVisitor/Reflector/FunctionLikeNodeScanner.php

@@ -32,6 +32,7 @@
 use Psalm\Issue\DuplicateMethod;
 use Psalm\Issue\DuplicateParam;
 use Psalm\Issue\InvalidDocblock;
+use Psalm\Issue\InvalidPropertyAssignment;
 use Psalm\Issue\MissingDocblockType;
 use Psalm\Issue\ParseError;
 use Psalm\Issue\PrivateFinalMethod;
@@ -626,6 +627,18 @@ public function start(PhpParser\Node\FunctionLike $stmt, bool $fake_method = fal
                     }
                 }
 
+                if ($this->codebase->analysis_php_version_id < 8_00_00) {
+                    if (IssueBuffer::accepts(
+                        new InvalidPropertyAssignment(
+                            'Promoted properties are only supported in PHP 8 or newer,'
+                            . ' but promoted property ' . $param_storage->name . ' found',
+                            new CodeLocation($this->file_scanner, $param, null, true),
+                        ),
+                    )) {
+                        return false;
+                    }
+                }
+
                 //no docblock type was provided for param but we have one for property
                 if ($var_comment_type) {
                     $param_storage->type = $var_comment_type;

tests/PropertyTypeTest.php

@@ -606,6 +606,18 @@ function foo() {
                     'MixedPropertyFetch',
                 ],
             ],
+            'promotedPropertyOldPhp' => [
+                'code' => '<?php
+                    class User
+                    {
+                        public function __construct(
+                            protected string $name,
+                        ){}
+                    }',
+                'assertions' => [],
+                'ignored_issues' => [],
+                'php_version' => '8.0',
+            ],
             'sharedPropertyInIf' => [
                 'code' => '<?php
                     class A {
@@ -2957,6 +2969,18 @@ public function barBar(): void
                     $a->foo = "bar";',
                 'error_message' => 'InvalidPropertyAssignment',
             ],
+            'promotedPropertyOldPhp' => [
+                'code' => '<?php
+                    class User
+                    {
+                        public function __construct(
+                            protected string $name,
+                        ){}
+                    }',
+                'error_message' => 'InvalidPropertyAssignment',
+                'ignored_issues' => [],
+                'php_version' => '7.4',
+            ],
             'badFetch' => [
                 'code' => '<?php
                     $a = "hello";