Module Newtype: Correctly declare and lower module newtypes to the ne…

…w visibility

Summary:
This diff adds declaration and lowering to enable module-level newtypes, completing the feature in the typechecker.

After this diff, module level newtypes will behave properly in the typechecker. At runtime, they act like regular type aliases and behave properly as such.

Reviewed By: hgoldstein

Differential Revision: D37467891

fbshipit-source-id: 616c47f58f62cd11b30a7aab7cd2cd917b7b3559

hphp/hack/src/decl/direct_decl_smart_constructors.rs

@@ -3070,7 +3070,7 @@ impl<'a, 'o, 't, S: SourceTextAllocator<'t, 'a>> FlattenSmartConstructors
         &mut self,
         attributes: Self::Output,
         modifiers: Self::Output,
-        _module_kw_opt: Self::Output,
+        module_kw_opt: Self::Output,
         keyword: Self::Output,
         name: Self::Output,
         generic_params: Self::Output,
@@ -3111,11 +3111,15 @@ impl<'a, 'o, 't, S: SourceTextAllocator<'t, 'a>> FlattenSmartConstructors
         let internal = modifiers
             .iter()
             .any(|m| m.as_visibility() == Some(aast::Visibility::Internal));
+        let is_module_newtype = module_kw_opt.is_ignored_token_with_kind(TokenKind::Module);
         let typedef = self.alloc(TypedefType {
             module: self.module,
             pos,
             vis: match keyword.token_kind() {
                 Some(TokenKind::Type) => aast::TypedefVisibility::Transparent,
+                Some(TokenKind::Newtype) if is_module_newtype => {
+                    aast::TypedefVisibility::OpaqueModule
+                }
                 Some(TokenKind::Newtype) => aast::TypedefVisibility::Opaque,
                 _ => aast::TypedefVisibility::Transparent,
             },

hphp/hack/src/hackc/emitter/emit_typedef.rs

@@ -46,7 +46,7 @@ fn emit_typedef<'a, 'arena, 'decl>(
         emitter,
         &tparams,
         typedef.kind.clone(),
-        typedef.vis.is_opaque(),
+        typedef.vis.is_opaque() || typedef.vis.is_opaque_module(),
     );
     let span = HhasSpan::from_pos(&typedef.span);
     let mut attrs = Attr::AttrNone;

hphp/hack/src/parser/lowerer/lowerer.rs

@@ -5294,6 +5294,7 @@ fn p_def<'a>(node: S<'a>, env: &mut Env<'a>) -> Result<Vec<ast::Def>> {
         AliasDeclaration(c) => {
             let tparams = p_tparam_l(false, &c.generic_parameter, env)?;
             let kinds = p_kinds(&c.modifiers, env)?;
+            let is_module_newtype = !c.module_kw_opt.is_missing();
             for tparam in tparams.iter() {
                 if tparam.reified != ast::ReifyKind::Erased {
                     raise_parsing_error(node, env, &syntax_error::invalid_reified)
@@ -5315,6 +5316,7 @@ fn p_def<'a>(node: S<'a>, env: &mut Env<'a>) -> Result<Vec<ast::Def>> {
                 mode: env.file_mode(),
                 vis: match token_kind(&c.keyword) {
                     Some(TK::Type) => ast::TypedefVisibility::Transparent,
+                    Some(TK::Newtype) if is_module_newtype => ast::TypedefVisibility::OpaqueModule,
                     Some(TK::Newtype) => ast::TypedefVisibility::Opaque,
                     _ => missing_syntax("kind", &c.keyword, env)?,
                 },

hphp/hack/test/fanout/modules/module-remove-decl.php

@@ -37,11 +37,11 @@
 <?hh
 <<file: __EnableUnstableFeatures('modules')>>
 module A;
-
+module newtype Bar = Foo;
 internal newtype Foo = int;
 //// changed-c-use.php
 <?hh
 <<file: __EnableUnstableFeatures('modules')>>
 module A;
-
+module newtype Bar = Foo;
 internal newtype Foo = int;

hphp/hack/test/fanout/modules/module-remove-decl.php.incr_no_old_decls.exp

@@ -6,5 +6,6 @@ b-use.php:3:8,8: Unbound name: `A` (a module) (Naming[2049])
 c-use.php:3:8,8: Unbound name: `A` (a module) (Naming[2049])
 === fanout ===
 Fun foobar
+Type Bar
 Type Foo
 Type FooA

hphp/hack/test/fanout/modules/module-remove-decl.php.incr_old_decl.exp

@@ -6,5 +6,6 @@ b-use.php:3:8,8: Unbound name: `A` (a module) (Naming[2049])
 c-use.php:3:8,8: Unbound name: `A` (a module) (Naming[2049])
 === fanout ===
 Fun foobar
+Type Bar
 Type Foo
 Type FooA

hphp/hack/test/fanout/modules/module-remove-decl.php.saved_state.exp

@@ -6,5 +6,6 @@ b-use.php:3:8,8: Unbound name: `A` (a module) (Naming[2049])
 c-use.php:3:8,8: Unbound name: `A` (a module) (Naming[2049])
 === fanout ===
 Fun foobar
+Type Bar
 Type Foo
 Type FooA

hphp/hack/test/typecheck/modules/module_newtype.php

@@ -0,0 +1,33 @@
+//// module.php
+<?hh
+<<file:__EnableUnstableFeatures("modules")>>
+new module foo {}
+
+//// decl.php
+<?hh
+<<file:__EnableUnstableFeatures("modules")>>
+module foo;
+module newtype Foo = FooInternal; // ok
+module newtype FooBad as FooInternal = FooInternal; // error
+internal class FooInternal {
+  public function foo(): void {}
+
+}
+function same_file(Foo $x) : void {
+  $x->foo(); // ok
+}
+
+//// use.php
+<?hh
+<<file:__EnableUnstableFeatures("modules")>>
+module foo;
+function same_module(Foo $x) : void {
+  $x->foo(); // ok, it's FooInternal
+}
+
+
+//// use_bad.php
+<?hh
+function bad(Foo $x): void {
+  $x->foo();
+}

hphp/hack/test/typecheck/modules/module_newtype.php.exp

@@ -0,0 +1,8 @@
+File "module_newtype.php--decl.php", line 5, characters 26-36:
+You cannot use this type in a public declaration. (Typing[4446])
+  File "module_newtype.php--decl.php", line 6, characters 16-26:
+  It is declared as `internal` here
+File "module_newtype.php--use_bad.php", line 3, characters 7-9:
+You are trying to access the method `foo` but this is a mixed value. Use a **specific** class or interface name. (Typing[4064])
+  File "module_newtype.php--use_bad.php", line 2, characters 14-16:
+  Definition is here

hphp/test/slow/modules/module_newtype.php

@@ -0,0 +1,25 @@
+<?hh
+<<file:__EnableUnstableFeatures("modules")>>
+module foo;
+module newtype Foo = FooInternal; // ok
+internal class FooInternal {
+  public function foo(): void {
+    echo "In function foo\n";
+  }
+
+}
+function same_file(Foo $x) : void {
+  $x->foo(); // ok
+}
+
+<<__EntryPoint>>
+function main(): void {
+  include "module_newtype_module.inc";
+  include "module_newtype_separate_file.inc";
+  include "module_newtype_outside_module.inc";
+
+  $x = new FooInternal();
+  same_file($x); // always ok
+  separate_file($x); // always ok
+  outside_module($x); // fails typechecker, but should pass at runtime
+}

hphp/test/slow/modules/module_newtype.php.expectf

@@ -0,0 +1,3 @@
+In function foo
+In function foo
+In function foo

hphp/test/slow/modules/module_newtype_module.inc

@@ -0,0 +1,3 @@
+<?hh
+<<file:__EnableUnstableFeatures("modules")>>
+new module foo {}

hphp/test/slow/modules/module_newtype_outside_module.inc

@@ -0,0 +1,5 @@
+<?hh
+<<file:__EnableUnstableFeatures("modules")>>
+function outside_module(Foo $x) : void {
+  $x->foo(); // ok
+}

hphp/test/slow/modules/module_newtype_separate_file.inc

@@ -0,0 +1,6 @@
+<?hh
+<<file:__EnableUnstableFeatures("modules")>>
+module foo;
+function separate_file(Foo $x) : void {
+  $x->foo(); // ok
+}