Eagerly reduce empty intersections to 'never'

2019-06-08 11:23:23 -07:00
1 changed files with 3 additions and 0 deletions
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@ -9956,6 +9956,9 @@ namespace ts {
                }
                else {
                    result = createIntersectionType(typeSet, aliasSymbol, aliasTypeArguments);
+                    if (isEmptyIntersectionType(<IntersectionType>result)) {
+                        result = neverType;
+                    }
                }
                intersectionTypes.set(id, result);
            }