Exclude MissingFields if RHS have an index signature

[kdy1]

Related test case:

stc/crates/stc_ts_type_checker/tests/conformance/types/members/objectTypeWithStringAndNumberIndexSignatureToAny.ts

Line 92 in 5d3aa0b

someObj = sToAny;

stc fails with

  x context:
  | lhs = instanceof  Obj;
  | rhs = StringTo#1;
  | Member as {
  |     [x: string]: any;
  | };
  | lhs (normalized) = Obj#1;
  | Member as {
  |     hello: string;
  |     world: number;
  | };
  | rhs (normalized) = StringTo#1;
  | Member as {
  |     [x: string]: any;
  | }; (at crates/stc_ts_file_analyzer/src/analyzer/assign/mod.rs:588:73)
  | context: tried to assign a type to an interface (at crates/stc_ts_file_analyzer/src/analyzer/assign/mod.rs:2277:18)
  | context: tried to assign to type elements by converting rhs to a type literal (at crates/stc_ts_file_analyzer/src/analyzer/assign/type_el.rs:228:30)
  | MissingFields {
  |     span: Span {
  |         lo: BytePos(
  |             2092,
  |         ),
  |         hi: BytePos(
  |             2099,
  |         ),
  |         ctxt: #0,
  |     },
  |     fields: [
  |         hello: string,
  |         world: number,
  |     ],
  | }
    ,-[$DIR/tests/conformance/types/members/objectTypeWithStringAndNumberIndexSignatureToAny.ts:91:1]
 91 |
 92 |     someObj = sToAny;
    :     ^^^^^^^
 93 |     someObj = nToNumber;
    `----

but it should success because the RHS contains an index signature

[awareness481]

What's causing me issues here is that it seems like the type gets converted to type Interface by this line

stc/crates/stc_ts_file_analyzer/src/ty/type_facts.rs

Line 71 in a02ed2a

ty = ty.fold_with(&mut TypeFactsHandler { analyzer: self, facts });

dbg!("before fold white: ", &ty);
ty = ty.fold_with(&mut TypeFactsHandler { analyzer: self, facts });
dbg!("after fold with: ", &ty);

[crates/stc_ts_file_analyzer/src/ty/type_facts.rs:72] "before fold with: " = "before fold with: "
[crates/stc_ts_file_analyzer/src/ty/type_facts.rs:72] &ty = Instance { span: Span { lo: BytePos(1229), hi: BytePos(1242), ctxt: #0 }, ty: StringTo<any>, metadata: InstanceMetadata { common: CommonTypeMetadata { implicit: false, infected_by_this_in_object_literal: false, prevent_converting_to_children: false, contains_infer_type: false, prevent_complex_simplification: false, resolved_from_var: false, prevent_generalization: false, destructure_key: DestructureId(0) } }, tracker: Tracker { _priv: () } }

[crates/stc_ts_file_analyzer/src/ty/type_facts.rs:74] "after fold with: " = "after fold with: "
[crates/stc_ts_file_analyzer/src/ty/type_facts.rs:74] &ty = Instance { span: Span { lo: BytePos(1229), hi: BytePos(1242), ctxt: #0 }, ty: Interface { span: Span { lo: BytePos(1229), hi: BytePos(1242), ctxt: #0 }, name: StringTo#2, type_params: Some(<T#3>), extends: [], body: [IndexSignature { span: Span { lo: BytePos(27), hi: BytePos(42), ctxt: #0 }, params: [(string)], type_ann: Some(any), readonly: false, is_static: false }], metadata: InterfaceMetadata { common: CommonTypeMetadata { implicit: false, infected_by_this_in_object_literal: false, prevent_converting_to_children: false, contains_infer_type: false, prevent_complex_simplification: false, resolved_from_var: false, prevent_generalization: false, destructure_key: DestructureId(0) } }, tracker: Tracker { _priv: () } }, metadata: InstanceMetadata { common: CommonTypeMetadata { implicit: false, infected_by_this_in_object_literal: false, prevent_converting_to_children: false, contains_infer_type: false, prevent_complex_simplification: false, resolved_from_var: false, prevent_generalization: false, destructure_key: DestructureId(0) } }, tracker: Tracker { _priv: () } }

Is this intended?

The ts code im using is this: (not representing the test code but im just using it to debug)

interface StringTo<T> {
  [x: string]: T;
}

interface NumberTo<T> {
  [x: number]: T;
}

interface StringAndNumberTo<T> extends StringTo<T>, NumberTo<T> {}

interface Obj {
  hello: string;
  world: number;
}

type NumberToNumber = NumberTo<number>;

interface StringToAnyNumberToNumber extends StringTo<any>, NumberToNumber {}

function f3(
  sToAny: StringTo<any>,
  nToNumber: NumberToNumber,
  strToAnyNumToNum: StringToAnyNumberToNumber,
  someObj: Obj
) {
  someObj = sToAny;
}

[kdy1]

I think it's a bug of the TypeFactHandler, but not sure how it did happen

[kdy1]

I came back to my macbook, and checked the source code of TypeFactsHandler, but not sure why it creates Interface.
The only line mention Interface is

stc/crates/stc_ts_file_analyzer/src/ty/type_facts.rs

Line 179 in a02ed2a

Type::Interface(..) | Type::TypeLit(..) | Type::Class(..) => return false,

but it seems innocent

[awareness481]

If it's any help I've deduced that this line is directly responsible:

stc/crates/stc_ts_file_analyzer/src/ty/type_facts.rs

Line 519 in a02ed2a

ty = ty.fold_children_with(self);

You can try putting return ty; before it and you'll see that the type won't get converted to Interface but if you do

        ty = ty.fold_children_with(self);
        return ty;

you will get Interface back.

[kdy1]

I'll try resolving this one

[kdy1]

Closing as it's now normalized.
Tracking issue for reverting normalization: #768