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feat: Union the type of an optional property of a mapped type with `u…
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…ndefined` (#1073)

**Description:**

```ts
function f10<T>(x: T, y: Partial<T>, k: keyof T) {
    x[k] = y[k];  // Error
    y[k] = x[k];
}
```
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@sunrabbit123
sunrabbit123 authored Aug 24, 2023
1 parent 57e0f3f commit f46b724
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137 changes: 74 additions & 63 deletions crates/stc_ts_file_analyzer/src/analyzer/expr/mod.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3129,81 +3129,92 @@ impl Analyzer<'_, '_> {
// If type of prop is equal to the type of index signature, it's
// index access.

match constraint.as_ref().map(Type::normalize) {
Some(Type::Index(Index {
ty: box Type::Array(..), ..
})) => {
if let Ok(obj) = self.env.get_global_type(span, &js_word!("Array")) {
return self.access_property(span, &obj, prop, type_mode, id_ctx, opts);
let result = (|obj| {
match constraint.as_ref().map(Type::normalize) {
Some(Type::Index(Index {
ty: box Type::Array(..), ..
})) => {
if let Ok(obj) = self.env.get_global_type(span, &js_word!("Array")) {
return self.access_property(span, &obj, prop, type_mode, id_ctx, opts);
}
}
}

Some(index @ Type::Keyword(..)) | Some(index @ Type::Param(..)) => {
// {
// [P in string]: number;
// };
if let Ok(()) = self.assign(span, &mut Default::default(), index, &prop.ty()) {
// We handle `Partial<string>` at here.
let ty = m.ty.clone().map(|v| *v).unwrap_or_else(|| Type::any(span, Default::default()));

let ty = match m.optional {
Some(TruePlusMinus::Plus) | Some(TruePlusMinus::True) => ty.union_with_undefined(span),
Some(TruePlusMinus::Minus) => self.apply_type_facts_to_type(TypeFacts::NEUndefined | TypeFacts::NENull, ty),
_ => ty,
};
return Ok(ty);
Some(index @ Type::Keyword(..)) | Some(index @ Type::Param(..)) => {
// {
// [P in string]: number;
// };
if let Ok(()) = self.assign(span, &mut Default::default(), index, &prop.ty()) {
// We handle `Partial<string>` at here.
let ty = m.ty.clone().map(|v| *v).unwrap_or_else(|| Type::any(span, Default::default()));

let ty = match m.optional {
Some(TruePlusMinus::Plus) | Some(TruePlusMinus::True) => ty.union_with_undefined(span),
Some(TruePlusMinus::Minus) => {
self.apply_type_facts_to_type(TypeFacts::NEUndefined | TypeFacts::NENull, ty)
}
_ => ty,
};
return Ok(ty);
}
}
}

_ => {}
}

let expanded = self
.expand_mapped(span, m)
.context("tried to expand a mapped type to access property")?;

if let Some(obj) = &expanded {
return self.access_property(span, obj, prop, type_mode, id_ctx, opts);
}
_ => {}
}

if let Some(Type::Index(Index { ty, .. })) = constraint.as_ref().map(Type::normalize) {
// Check if we can index the object with given key.
if let Ok(index_type) = self.keyof(span, ty) {
if let Ok(()) = self.assign_with_opts(
&mut Default::default(),
&index_type,
&prop.ty(),
AssignOpts {
span,
..Default::default()
},
) {
let mut result_ty = m.ty.clone().map(|v| *v).unwrap_or_else(|| Type::any(span, Default::default()));
if let Some(obj) = self
.expand_mapped(span, m)
.context("tried to expand a mapped type to access property")?
{
return self.access_property(span, &obj, prop, type_mode, id_ctx, opts);
}

replace_type(
&mut result_ty,
|ty| match ty.normalize() {
Type::Param(ty) => ty.name == m.type_param.name,
_ => false,
if let Some(Type::Index(Index { ty, .. })) = constraint.as_ref().map(Type::normalize) {
// Check if we can index the object with given key.
if let Ok(index_type) = self.keyof(span, ty) {
if let Ok(()) = self.assign_with_opts(
&mut Default::default(),
&index_type,
&prop.ty(),
AssignOpts {
span,
..Default::default()
},
|_| Some(index_type.clone()),
);
) {
let mut result_ty = m.ty.clone().map(|v| *v).unwrap_or_else(|| Type::any(span, Default::default()));

replace_type(
&mut result_ty,
|ty| match ty.normalize() {
Type::Param(ty) => ty.name == m.type_param.name,
_ => false,
},
|_| Some(index_type.clone()),
);

return Ok(result_ty);
return Ok(result_ty);
}
}
}
}

warn!("Creating an indexed access type with mapped type as the object");
warn!("Creating an indexed access type with mapped type as the object");

return Ok(Type::IndexedAccessType(IndexedAccessType {
span,
readonly: false,
obj_type: Box::new(obj),
index_type: Box::new(prop.ty().into_owned()),
metadata: Default::default(),
tracker: Default::default(),
}));
return Ok(Type::IndexedAccessType(IndexedAccessType {
span,
readonly: false,
obj_type: Box::new(obj),
index_type: Box::new(prop.ty().into_owned()),
metadata: Default::default(),
tracker: Default::default(),
}));
})(obj.clone())
.map(|v| {
if let Some(TruePlusMinus::True) = m.optional {
Type::new_union(span, vec![v, Type::undefined(span, Default::default())])
} else {
v
}
});
return result;
}

Type::Ref(r) => {
Expand Down
3 changes: 1 addition & 2 deletions ...tc_ts_type_checker/tests/conformance/types/mapped/mappedTypeRelationships.error-diff.json
View file
Original file line number Diff line number Diff line change
@@ -1,14 +1,13 @@
{
"required_errors": {
"TS2322": 13,
"TS2322": 12,
"TS2536": 4,
"TS2542": 4
},
"required_error_lines": {
"TS2322": [
14,
19,
33,
75,
81,
91,
Expand Down
4 changes: 2 additions & 2 deletions ...c_ts_type_checker/tests/conformance/types/mapped/mappedTypeRelationships.stats.rust-debug
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
Stats {
required_error: 21,
matched_error: 7,
required_error: 20,
matched_error: 8,
extra_error: 5,
panic: 0,
}
4 changes: 2 additions & 2 deletions crates/stc_ts_type_checker/tests/tsc-stats.rust-debug
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
Stats {
required_error: 3501,
matched_error: 6534,
required_error: 3500,
matched_error: 6535,
extra_error: 763,
panic: 73,
}

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