microsoft/TypeScript
1
0
Fork 0
mirror of https://github.com/microsoft/TypeScript.git synced 2026-05-15 04:43:37 -05:00
Code Issues Packages Projects Releases 212 Wiki Activity

Don't elaborate on primitives at all.

Browse Source
This commit is contained in:
Daniel Rosenwasser
2018-06-28 15:34:27 -07:00
parent 12a201c29e
commit c853d7c048
1 changed files with 7 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

13
src/compiler/checker.ts
View File

@@ -10633,13 +10633,14 @@ namespace ts {
// Try to see if we're relating something like `Foo` -> `Bar | null | undefined`.
// If so, reporting the `null` and `undefined` in the type is hardly useful.
// First, see if we're even relating an atomic type to a union.
// First, see if we're even relating an object type to a union.
// Then see if the target is stripped down to a single non-union type.
// We actually want to remove null and undefined naively here (rather than getNonNullableType),
// since we don't want to end up with a worse error like "`Foo` is not assignable to `NonNullable<T>`"
// when dealing with generics.
if (target.flags & TypeFlags.Union &&
source.flags & ((TypeFlags.Primitive | TypeFlags.Object) & ~(TypeFlags.Nullable | TypeFlags.Void)) &&
// Note
// * We actually want to remove null and undefined naively here (rather than using getNonNullableType),
// since we don't want to end up with a worse error like "`Foo` is not assignable to `NonNullable<T>`"
// when dealing with generics.
// * We also don't deal with primitive source types, since we already halt elaboration below.
if (target.flags & TypeFlags.Union && source.flags & TypeFlags.Object &&
(target as UnionType).types.length <= 3 && maybeTypeOfKind(target, TypeFlags.Nullable)) {
const nullStrippedTarget = extractTypesOfKind(target, ~TypeFlags.Nullable);
if (!(nullStrippedTarget.flags & (TypeFlags.Union | TypeFlags.Never))) {