| commit | ab841600a2027c6fa434da30ba874ed0e7f64f37 | |
| author | Andrew Kennedy <akenn@fb.com> | |
| Mon, 11 Feb 2019 10:24:25 +0000 (11 02:24 -0800) | ||
| committer | Hhvm Bot <hhvm-bot@users.noreply.github.com> | |
| Mon, 11 Feb 2019 10:29:33 +0000 (11 02:29 -0800) | ||
| tree | ebcb4d21fbfb46b0a168f5ed62ff8570d1556c8a | treesnapshot (tar.gz zip) |
| parent | 0daa0a4e38bd296a2f3f826f92511977a8f8b695 | commitdiff |
New inference: flatten unions when solving for lower bounds
Summary:
Currently it is possible for a solution to a type variable to contain nested unions. e.g. if we have
```
int, (string | int) <: v
```
then we will solve with `v := int | (string | int)`. Also, we might end up with spurious "circular type" errors if `v` occurs somewhere in the flattened union, even though `v | t <: v` iff `t <: v`.
So before creating the union, we normalize the set of types, flattening unions, locating `null` and nullable types, and removing `v` from the set.
Reviewed By: manzyuk
Differential Revision: D13986135
fbshipit-source-id: 847ff1083ba6501792d06e1aeb7686b066db5212
Summary:
Currently it is possible for a solution to a type variable to contain nested unions. e.g. if we have
```
int, (string | int) <: v
```
then we will solve with `v := int | (string | int)`. Also, we might end up with spurious "circular type" errors if `v` occurs somewhere in the flattened union, even though `v | t <: v` iff `t <: v`.
So before creating the union, we normalize the set of types, flattening unions, locating `null` and nullable types, and removing `v` from the set.
Reviewed By: manzyuk
Differential Revision: D13986135
fbshipit-source-id: 847ff1083ba6501792d06e1aeb7686b066db5212