Fix StaticCallOnNonStaticToInstanceCallRector for same-class calls (#7876)

When calling a non-static method statically from within the same class,
convert to $this->method() instead of skipping. This eliminates the
PHP deprecation warning for non-static method called statically.

Calls to ancestor methods (e.g., Grandpa::method() from a descendant)
are still skipped as they are valid non-static usage.

Author: carlos-granados

rules-tests/Php70/Rector/StaticCall/StaticCallOnNonStaticToInstanceCallRector/Fixture/same_class_non_static.php.inc

@@ -0,0 +1,37 @@
+<?php
+
+namespace Rector\Tests\Php70\Rector\StaticCall\StaticCallOnNonStaticToInstanceCallRector\Fixture;
+
+class SameClassNonStatic
+{
+    public function run()
+    {
+        return SameClassNonStatic::doWork();
+    }
+
+    public function doWork()
+    {
+        return 'work done';
+    }
+}
+
+?>
+-----
+<?php
+
+namespace Rector\Tests\Php70\Rector\StaticCall\StaticCallOnNonStaticToInstanceCallRector\Fixture;
+
+class SameClassNonStatic
+{
+    public function run()
+    {
+        return $this->doWork();
+    }
+
+    public function doWork()
+    {
+        return 'work done';
+    }
+}
+
+?>

rules/Php70/Rector/StaticCall/StaticCallOnNonStaticToInstanceCallRector.php

@@ -10,6 +10,7 @@
 use PhpParser\Node\Expr\New_;
 use PhpParser\Node\Expr\PropertyFetch;
 use PhpParser\Node\Expr\StaticCall;
+use PhpParser\Node\Expr\Variable;
 use PHPStan\Analyser\Scope;
 use PHPStan\Reflection\ClassReflection;
 use PHPStan\Reflection\MethodReflection;
@@ -123,6 +124,11 @@ public function refactor(Node $node): ?Node
             return null;
         }
 
+        $classReflection = $scope->getClassReflection();
+        if ($classReflection instanceof ClassReflection && $classReflection->getName() === $className) {
+            return new MethodCall(new Variable('this'), $node->name, $node->args);
+        }
+
         if ($this->isInstantiable($className, $scope)) {
             $new = new New_($node->class);
             return new MethodCall($new, $node->name, $node->args);
@@ -168,8 +174,11 @@ private function shouldSkip(string $methodName, string $className, StaticCall $s
             return true;
         }
 
-        $reflection = $scope->getClassReflection();
-        if ($reflection instanceof ClassReflection && $reflection->is($className)) {
+        $currentClassReflection = $scope->getClassReflection();
+        if ($currentClassReflection instanceof ClassReflection
+            && $this->reflectionProvider->hasClass($className)
+            && $currentClassReflection->isSubclassOfClass($this->reflectionProvider->getClass($className))
+        ) {
             return true;
         }