Filter nullables after lifting union over spread

sandersn · sandersn · commit 93465bdae2af · 2017-06-06T14:11:01.000-07:00
Previously, null/undefined were removed upfront, which is incorrect. Now
nullable types are removed with other non-primitives after union is
lifted over spread. This produces unions, which are larger, but more correct.
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -7632,11 +7632,9 @@ namespace ts {
             if (left.flags & TypeFlags.Any || right.flags & TypeFlags.Any) {
                 return anyType;
             }
-            left = filterType(left, t => !(t.flags & TypeFlags.Nullable));
             if (left.flags & TypeFlags.Never) {
                 return right;
             }
-            right = filterType(right, t => !(t.flags & TypeFlags.Nullable));
             if (right.flags & TypeFlags.Never) {
                 return left;
             }

Original file line number	Diff line number	Diff line change
`@@ -7632,11 +7632,9 @@ namespace ts {`
`7632`	`7632`	`if (left.flags & TypeFlags.Any \|\| right.flags & TypeFlags.Any) {`
`7633`	`7633`	`return anyType;`
`7634`	`7634`	`}`
`7635`		`- left = filterType(left, t => !(t.flags & TypeFlags.Nullable));`
`7636`	`7635`	`if (left.flags & TypeFlags.Never) {`
`7637`	`7636`	`return right;`
`7638`	`7637`	`}`
`7639`		`- right = filterType(right, t => !(t.flags & TypeFlags.Nullable));`
`7640`	`7638`	`if (right.flags & TypeFlags.Never) {`
`7641`	`7639`	`return left;`
`7642`	`7640`	`}`