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Jack Williams (jack-williams) wants to merge 4 commits into from
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WIP: in narrowing with record types #41478

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45e3cbb
Initial attempt and property witness for in
jack-williams Nov 10, 2020
7ea6203
Improve narrowing logic
jack-williams Nov 10, 2020
66bd973
Remove redundant branch
jack-williams Nov 10, 2020
0bebeb6
Remove another redundant check
jack-williams Nov 10, 2020
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21 changes: 20 additions & 1 deletion src/compiler/checker.ts
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Original file line numberDiff line numberDiff line change
Expand Up@@ -722,6 +722,7 @@ namespace ts {
const templateLiteralTypes = new Map<string, TemplateLiteralType>();
const stringMappingTypes = new Map<string, StringMappingType>();
const substitutionTypes = new Map<string, SubstitutionType>();
const propertyWitnessRecordTypes = new Map<string, Type>();
const evolvingArrayTypes: EvolvingArrayType[] = [];
const undefinedProperties: SymbolTable = new Map();

Expand DownExpand Up@@ -915,6 +916,7 @@ namespace ts {
let deferredGlobalExtractSymbol: Symbol;
let deferredGlobalOmitSymbol: Symbol;
let deferredGlobalBigIntType: ObjectType;
let deferredGlobalRecordSymbol: Symbol;

const allPotentiallyUnusedIdentifiers = new Map<Path, PotentiallyUnusedIdentifier[]>(); // key is file name

Expand DownExpand Up@@ -12658,6 +12660,10 @@ namespace ts {
return deferredGlobalBigIntType || (deferredGlobalBigIntType = getGlobalType("BigInt" as __String, /*arity*/ 0, reportErrors)) || emptyObjectType;
}

function getGlobalRecordSymbol(): Symbol {
return deferredGlobalRecordSymbol || (deferredGlobalRecordSymbol = getGlobalSymbol("Record" as __String, SymbolFlags.TypeAlias, Diagnostics.Cannot_find_global_type_0)!);
}

/**
* Instantiates a global type that is generic with some element type, and returns that instantiation.
*/
Expand DownExpand Up@@ -22169,7 +22175,20 @@ namespace ts {
|| isThisTypeParameter(type)
|| type.flags & TypeFlags.Intersection && every((type as IntersectionType).types, t => t.symbol !== globalThisSymbol)) {
const propName = escapeLeadingUnderscores(literal.text);
return filterType(type, t => isTypePresencePossible(t, propName, assumeTrue));
const narrowed = filterType(type, t => isTypePresencePossible(t, propName, assumeTrue));
if (assumeTrue && (narrowed.flags & TypeFlags.Never)) {
const recordTypeAlias = getGlobalRecordSymbol();
if (!recordTypeAlias) {
return errorType;
}
let record = propertyWitnessRecordTypes.get(literal.text);
if (!record) {
record = getTypeAliasInstantiation(recordTypeAlias, [getLiteralType(literal.text), unknownType]);
propertyWitnessRecordTypes.set(literal.text, record);
}
return getIntersectionType([type, record]);
}
return narrowed;
}
return type;
}
Expand Down
12 changes: 8 additions & 4 deletions tests/baselines/reference/inKeywordTypeguard.errors.txt
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Expand Up@@ -5,8 +5,10 @@ tests/cases/compiler/inKeywordTypeguard.ts(16,11): error TS2339: Property 'a' do
tests/cases/compiler/inKeywordTypeguard.ts(27,11): error TS2339: Property 'b' does not exist on type 'AWithOptionalProp | BWithOptionalProp'.
Property 'b' does not exist on type 'AWithOptionalProp'.
tests/cases/compiler/inKeywordTypeguard.ts(42,11): error TS2339: Property 'b' does not exist on type 'AWithMethod'.
tests/cases/compiler/inKeywordTypeguard.ts(49,11): error TS2339: Property 'a' does not exist on type 'never'.
tests/cases/compiler/inKeywordTypeguard.ts(50,11): error TS2339: Property 'b' does not exist on type 'never'.
tests/cases/compiler/inKeywordTypeguard.ts(49,11): error TS2339: Property 'a' does not exist on type '(AWithMethod & Record<"c", unknown>) | (BWithMethod & Record<"c", unknown>)'.
Property 'a' does not exist on type 'BWithMethod & Record<"c", unknown>'.
tests/cases/compiler/inKeywordTypeguard.ts(50,11): error TS2339: Property 'b' does not exist on type '(AWithMethod & Record<"c", unknown>) | (BWithMethod & Record<"c", unknown>)'.
Property 'b' does not exist on type 'AWithMethod & Record<"c", unknown>'.
tests/cases/compiler/inKeywordTypeguard.ts(52,11): error TS2339: Property 'a' does not exist on type 'AWithMethod | BWithMethod'.
Property 'a' does not exist on type 'BWithMethod'.
tests/cases/compiler/inKeywordTypeguard.ts(53,11): error TS2339: Property 'b' does not exist on type 'AWithMethod | BWithMethod'.
Expand DownExpand Up@@ -85,10 +87,12 @@ tests/cases/compiler/inKeywordTypeguard.ts(94,26): error TS2339: Property 'a' do
if ("c" in x) {
x.a();
~
!!! error TS2339: Property 'a' does not exist on type 'never'.
!!! error TS2339: Property 'a' does not exist on type '(AWithMethod & Record<"c", unknown>) | (BWithMethod & Record<"c", unknown>)'.
!!! error TS2339: Property 'a' does not exist on type 'BWithMethod & Record<"c", unknown>'.
x.b();
~
!!! error TS2339: Property 'b' does not exist on type 'never'.
!!! error TS2339: Property 'b' does not exist on type '(AWithMethod & Record<"c", unknown>) | (BWithMethod & Record<"c", unknown>)'.
!!! error TS2339: Property 'b' does not exist on type 'AWithMethod & Record<"c", unknown>'.
} else {
x.a();
~
Expand Down
4 changes: 2 additions & 2 deletions tests/baselines/reference/inKeywordTypeguard.types
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Expand Up@@ -146,13 +146,13 @@ function negativeTestClassesWithMemberMissingInBothClasses(x: AWithMethod | BWit
x.a();
>x.a() : any
>x.a : any
>x : never
>x : (AWithMethod & Record<"c", unknown>) | (BWithMethod & Record<"c", unknown>)
>a : any

x.b();
>x.b() : any
>x.b : any
>x : never
>x : (AWithMethod & Record<"c", unknown>) | (BWithMethod & Record<"c", unknown>)
>b : any

} else {
Expand Down