test(zend, reflection): add generics test suite and fix uncovered semantics

Signed-off-by: azjezz <azjezz@protonmail.com>

Author: azjezz

Zend/tests/generics/erasure/arrow_fn_erasure.phpt

@@ -0,0 +1,10 @@
+--TEST--
+Erasure: arrow function with type parameters erases to bound
+--FILE--
+<?php
+$f = fn<T : int>(T $x): T => $x;
+$r = new ReflectionFunction($f);
+echo $r->getParameters()[0]->getType()->__toString(), "\n";
+?>
+--EXPECT--
+int

Zend/tests/generics/erasure/bound_object.phpt

@@ -0,0 +1,12 @@
+--TEST--
+Erasure: T : object erases to object
+--FILE--
+<?php
+function id<T : object>(T $x): T { return $x; }
+$r = new ReflectionFunction('id');
+echo $r->getParameters()[0]->getType()->__toString(), "\n";
+echo $r->getReturnType()->__toString(), "\n";
+?>
+--EXPECT--
+object
+object

Zend/tests/generics/erasure/bound_to_class.phpt

@@ -0,0 +1,13 @@
+--TEST--
+Erasure: T : Foo erases to Foo
+--FILE--
+<?php
+class Foo {}
+function id<T : Foo>(T $x): T { return $x; }
+$r = new ReflectionFunction('id');
+echo $r->getParameters()[0]->getType()->getName(), "\n";
+echo $r->getReturnType()->getName(), "\n";
+?>
+--EXPECT--
+Foo
+Foo

Zend/tests/generics/erasure/builtin_array_erasure.phpt

@@ -0,0 +1,18 @@
+--TEST--
+Erasure: array<...> erases to plain array at runtime
+--FILE--
+<?php
+function f(array<int> $x): array<string, int> { return $x; }
+$r = new ReflectionFunction('f');
+$pt = $r->getParameters()[0]->getType();
+echo $pt->getName(), "\n";
+$rt = $r->getReturnType();
+echo $rt->getName(), "\n";
+
+f([1, 2, 3]);
+echo "ok\n";
+?>
+--EXPECT--
+array
+array
+ok

Zend/tests/generics/erasure/closure_erasure.phpt

@@ -0,0 +1,10 @@
+--TEST--
+Erasure: closure with type parameters erases to bound
+--FILE--
+<?php
+$f = function <T : object>(T $x): T { return $x; };
+$r = new ReflectionFunction($f);
+echo $r->getParameters()[0]->getType()->__toString(), "\n";
+?>
+--EXPECT--
+object

Zend/tests/generics/erasure/composite_bound.phpt

@@ -0,0 +1,11 @@
+--TEST--
+Erasure: composite bound erased
+--FILE--
+<?php
+class A {}
+function f<T : A|int>(T $x): T { return $x; }
+$rt = (new ReflectionFunction('f'))->getReturnType();
+echo get_class($rt), "\n";
+?>
+--EXPECT--
+ReflectionUnionType

Zend/tests/generics/erasure/erased_signature_match.phpt

@@ -0,0 +1,20 @@
+--TEST--
+Erasure: generic signature matches hand-erased equivalent
+--FILE--
+<?php
+class Foo {}
+
+class Generic<T : Foo> {
+    public function get(): T { return new Foo; }
+}
+
+class Erased {
+    public function get(): Foo { return new Foo; }
+}
+
+$rg = (new ReflectionClass('Generic'))->getMethod('get')->getReturnType()->__toString();
+$re = (new ReflectionClass('Erased'))->getMethod('get')->getReturnType()->__toString();
+var_dump($rg === $re);
+?>
+--EXPECT--
+bool(true)

Zend/tests/generics/erasure/extends_args_discarded.phpt

@@ -0,0 +1,13 @@
+--TEST--
+Erasure: extends type arguments don't change runtime parent
+--FILE--
+<?php
+class Base<T> {}
+class Derived extends Base<int> {}
+echo (new ReflectionClass('Derived'))->getParentClass()->getName(), "\n";
+$d = new Derived;
+var_dump($d instanceof Base);
+?>
+--EXPECT--
+Base
+bool(true)

Zend/tests/generics/erasure/generic_class_param.phpt

@@ -0,0 +1,13 @@
+--TEST--
+Erasure: generic class parameter type erased to bound
+--FILE--
+<?php
+interface Iface {}
+class Box<T : Iface> {
+    public function set(T $x): void {}
+}
+$rm = (new ReflectionClass('Box'))->getMethod('set');
+echo $rm->getParameters()[0]->getType()->getName(), "\n";
+?>
+--EXPECT--
+Iface

Zend/tests/generics/erasure/get_class_returns_erased.phpt

@@ -0,0 +1,10 @@
+--TEST--
+Erasure: get_class returns the erased class name
+--FILE--
+<?php
+class Box<T> {}
+$b = new Box::<int>;
+echo get_class($b), "\n";
+?>
+--EXPECT--
+Box