Add a function to convert string into lazyclass

Summary: In order to unblock modularity migration, we need a backdoor to allow converting strings to lazy classes. Here's a simple implementation.

Reviewed By: jamesjwu

Differential Revision: D40284561

fbshipit-source-id: 0077e6f161b344aab0ac67b7e69d2640c759b41c

Author: oulgen

hphp/runtime/ext/hh/ext_hh.cpp

@@ -1011,6 +1011,10 @@ TypedValue HHVM_FUNCTION(dynamic_class_meth_force, StringArg cls,
   return dynamicClassMeth<DynamicAttr::Ignore, false>(cls.get(), meth.get());
 }
 
+TypedValue HHVM_FUNCTION(classname_from_string_unsafe, StringArg cls) {
+  return make_tv<KindOfLazyClass>(LazyClassData::create(cls.get()));
+}
+
 namespace {
 
 const StaticString
@@ -1480,6 +1484,7 @@ static struct HHExtension final : Extension {
     X(dynamic_fun_force);
     X(dynamic_class_meth);
     X(dynamic_class_meth_force);
+    X(classname_from_string_unsafe);
     X(enable_per_file_coverage);
     X(disable_per_file_coverage);
     X(get_files_with_coverage);

hphp/runtime/ext/hh/ext_hh.php

@@ -255,6 +255,13 @@ function dynamic_fun_force(string $name)[]: mixed;
 <<__Native>>
 function dynamic_class_meth_force(string $cls, string $meth)[]: mixed;
 
+/**
+ * Creates a LazyClass pointer from input $classname. It does not eagerly
+ * verify that the $classname is in fact a valid class.
+ */
+<<__Native>>
+function classname_from_string_unsafe(string $classname)[]: mixed;
+
 /**
  * Begin collecting code coverage on all subsequent calls into files in $files
  * during this request.

hphp/runtime/ext/std/ext_std_intrinsics.cpp

@@ -399,6 +399,10 @@ Variant HHVM_FUNCTION(create_clsmeth_pointer, StringArg cls, StringArg meth) {
   return Variant{ClsMethDataRef::create(c, m)};
 }
 
+bool HHVM_FUNCTION(is_lazy_class, TypedValue val) {
+  return tvIsLazyClass(val);
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 bool HHVM_FUNCTION(is_unit_loaded, StringArg path) {
@@ -522,6 +526,7 @@ void StandardExtension::initIntrinsics() {
   HHVM_FALIAS(__hhvm_intrinsics\\create_class_pointer, create_class_pointer);
   HHVM_FALIAS(__hhvm_intrinsics\\create_clsmeth_pointer,
               create_clsmeth_pointer);
+  HHVM_FALIAS(__hhvm_intrinsics\\is_lazy_class, is_lazy_class);
 
   HHVM_FALIAS(__hhvm_intrinsics\\is_unit_loaded, is_unit_loaded);
   HHVM_FALIAS(__hhvm_intrinsics\\drain_unit_prefetcher, drain_unit_prefetcher);

hphp/runtime/ext/std/ext_std_intrinsics.php

@@ -76,6 +76,9 @@ function create_class_pointer(string $name): mixed;
 <<__Native>>
 function create_clsmeth_pointer(string $cls, string $meth): mixed;
 
+<<__Native>>
+function is_lazy_class(mixed $val): bool;
+
 <<__Native>>
 function dummy_lots_inout(inout $p1, inout $p2, inout $p3, inout $p4,
                           inout $p1, inout $p2, inout $p3, inout $p4,

hphp/test/slow/class-ptr/lazy-class-create-1.php

@@ -0,0 +1,9 @@
+<?hh
+
+class C {}
+
+<<__EntryPoint>>
+function main() {
+  var_dump(__hhvm_intrinsics\is_lazy_class(HH\classname_from_string_unsafe("C")));
+  var_dump(__hhvm_intrinsics\is_lazy_class(HH\classname_from_string_unsafe("WHOAMI")));
+}

hphp/test/slow/class-ptr/lazy-class-create-1.php.expect

@@ -0,0 +1,2 @@
+bool(true)
+bool(true)