From 4636777b1ce7739614882a88dacf77bb1b3d01fe Mon Sep 17 00:00:00 2001
From: Catherine Gasnier <catg@fb.com>
Date: Thu, 13 May 2021 09:25:53 -0700
Subject: [PATCH] opaque types should provide proper constraints on their type
 params

Summary: See added test case for an example. This test case use to not have any error.

Reviewed By: andrewjkennedy

Differential Revision: D28380086

fbshipit-source-id: 7a2a519ec6d233b4cdbfbd41be0fb47513d77b12
---
 hphp/hack/src/typing/typing_check_decls.ml           | 16 ++++++++++------
 .../hack/test/typecheck/constraint_newtype_param.php |  9 +++++++++
 .../test/typecheck/constraint_newtype_param.php.exp  |  8 ++++++++
 .../test/typecheck/constraints/tapply_is_newtype.php |  2 +-
 .../typecheck/constraints/tapply_is_newtype.php.exp  | 20 ++++++++++----------
 hphp/hack/test/typecheck/constraints/typedef.php     |  2 +-
 hphp/hack/test/typecheck/newtype8.php                |  2 +-
 7 files changed, 40 insertions(+), 19 deletions(-)
 create mode 100644 hphp/hack/test/typecheck/constraint_newtype_param.php
 create mode 100644 hphp/hack/test/typecheck/constraint_newtype_param.php.exp
 rewrite hphp/hack/test/typecheck/constraints/tapply_is_newtype.php.exp (74%)

diff --git a/hphp/hack/src/typing/typing_check_decls.ml b/hphp/hack/src/typing/typing_check_decls.ml
index c152bb24329..108bb1a2aa6 100644
--- a/hphp/hack/src/typing/typing_check_decls.ml
+++ b/hphp/hack/src/typing/typing_check_decls.ml
@@ -349,7 +349,7 @@ let typedef tenv t =
     t_constraint;
     t_kind;
     t_mode = _;
-    t_vis = _;
+    t_vis;
     t_namespace = _;
     t_user_attributes = _;
     t_span = _;
@@ -375,11 +375,15 @@ let typedef tenv t =
   check_hint_wellkindedness tenv_with_typedef_tparams t_kind;
   let env =
     {
-      (* Since typedefs cannot have constraints we shouldn't check
-       * if its type params satisfy the constraints of any tapply it
-       * references.
-       *)
-      typedef_tparams = t.t_tparams;
+      typedef_tparams =
+        ( if equal_typedef_visibility t_vis Transparent then
+          (* Since type aliases cannot have constraints we shouldn't check
+           * if its type params satisfy the constraints of any tapply it
+           * references.
+           *)
+          t.t_tparams
+        else
+          [] );
       tenv;
     }
   in
diff --git a/hphp/hack/test/typecheck/constraint_newtype_param.php b/hphp/hack/test/typecheck/constraint_newtype_param.php
new file mode 100644
index 00000000000..19bef470b3d
--- /dev/null
+++ b/hphp/hack/test/typecheck/constraint_newtype_param.php
@@ -0,0 +1,9 @@
+//// file1.php
+<?hh
+class A<T as bool> {}
+newtype B<T as int> = A<T>;
+
+//// file2.php
+<?hh
+
+function foo(B<string> $_): void {}
diff --git a/hphp/hack/test/typecheck/constraint_newtype_param.php.exp b/hphp/hack/test/typecheck/constraint_newtype_param.php.exp
new file mode 100644
index 00000000000..2d6d51b5f51
--- /dev/null
+++ b/hphp/hack/test/typecheck/constraint_newtype_param.php.exp
@@ -0,0 +1,8 @@
+File "constraint_newtype_param.php--file1.php", line 3, characters 23-26:
+Some type constraint(s) here are violated (Typing[4323])
+  File "constraint_newtype_param.php--file1.php", line 2, characters 9-9:
+  `T` is a constrained type parameter
+  File "constraint_newtype_param.php--file1.php", line 2, characters 14-17:
+  Expected `bool`
+  File "constraint_newtype_param.php--file1.php", line 3, characters 25-25:
+  But got `T as int`
diff --git a/hphp/hack/test/typecheck/constraints/tapply_is_newtype.php b/hphp/hack/test/typecheck/constraints/tapply_is_newtype.php
index b8196167047..232de4721c1 100644
--- a/hphp/hack/test/typecheck/constraints/tapply_is_newtype.php
+++ b/hphp/hack/test/typecheck/constraints/tapply_is_newtype.php
@@ -3,7 +3,7 @@
 
 interface Constraint<T as num> {}
 
-newtype NewConstraint<T> as Constraint<T> = Constraint<T>;
+newtype NewConstraint<T as num> as Constraint<T> = Constraint<T>;
 
 //// file2.php
 <?hh // strict
diff --git a/hphp/hack/test/typecheck/constraints/tapply_is_newtype.php.exp b/hphp/hack/test/typecheck/constraints/tapply_is_newtype.php.exp
dissimilarity index 74%
index 386dfc4d4ab..2b5b212f00c 100644
--- a/hphp/hack/test/typecheck/constraints/tapply_is_newtype.php.exp
+++ b/hphp/hack/test/typecheck/constraints/tapply_is_newtype.php.exp
@@ -1,10 +1,10 @@
-File "tapply_is_newtype.php--file2.php", line 4, characters 18-37:
-Some type constraint(s) here are violated (Typing[4323])
-File "tapply_is_newtype.php--file1.php", line 3, characters 22-22:
-`T` is a constrained type parameter
-File "tapply_is_newtype.php--file1.php", line 3, characters 27-29:
-Expected `num`
-File "tapply_is_newtype.php--file2.php", line 4, characters 32-36:
-But got `mixed`
-File "tapply_is_newtype.php--file1.php", line 5, characters 40-40:
-  via this generic `T`
+File "tapply_is_newtype.php--file2.php", line 4, characters 18-37:
+Some type constraint(s) here are violated (Typing[4323])
+  File "tapply_is_newtype.php--file1.php", line 3, characters 22-22:
+  `T` is a constrained type parameter
+  File "tapply_is_newtype.php--file1.php", line 3, characters 27-29:
+  Expected `num`
+  File "tapply_is_newtype.php--file2.php", line 4, characters 32-36:
+  But got `mixed`
+  File "tapply_is_newtype.php--file1.php", line 5, characters 47-47:
+    via this generic `T`
diff --git a/hphp/hack/test/typecheck/constraints/typedef.php b/hphp/hack/test/typecheck/constraints/typedef.php
index 9959370fdea..7c2e85a4b66 100644
--- a/hphp/hack/test/typecheck/constraints/typedef.php
+++ b/hphp/hack/test/typecheck/constraints/typedef.php
@@ -6,4 +6,4 @@ interface Constraint<T as num> {}
 // definitions since they cannot put constraints on their type parameters
 type AliasConstraint<T> = Constraint<T>;
 
-newtype NewConstraint<T> as Constraint<T> = AliasConstraint<T>;
+newtype NewConstraint<T as num> as Constraint<T> = AliasConstraint<T>;
diff --git a/hphp/hack/test/typecheck/newtype8.php b/hphp/hack/test/typecheck/newtype8.php
index fe06fabb5c0..f70e74319d6 100644
--- a/hphp/hack/test/typecheck/newtype8.php
+++ b/hphp/hack/test/typecheck/newtype8.php
@@ -3,7 +3,7 @@
 newtype FooInt as int = int;
 newtype FooString as string = string;
 newtype FooArray<T> as varray<T> = varray<T>;
-newtype FooMap<Tk, Tv> as Map<Tk, Tv> = Map<Tk, Tv>;
+newtype FooMap<Tk as arraykey, Tv> as Map<Tk, Tv> = Map<Tk, Tv>;
 
 //// test.php
 <?hh // strict
-- 
2.11.4.GIT