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merged 3 commits into from
Mar 19, 2020
Merged

Allow nested conditionals to be related via constraints #37208

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b554a2f
Allow nested conditionals to be related via constraints
weswigham Mar 4, 2020
31f4c93
Delete word in comment
weswigham Mar 19, 2020
8327b89
Merge branch 'master' into loosen-conditional-assignability
weswigham Mar 19, 2020
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16 changes: 10 additions & 6 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -16040,19 +16040,23 @@ namespace ts {
}
}
else {
// conditionals aren't related to one another via distributive constraint as it is much too inaccurate and allows way
// more assignments than are desirable (since it maps the source check type to its constraint, it loses information)
const distributiveConstraint = getConstraintOfDistributiveConditionalType(<ConditionalType>source);
if (distributiveConstraint) {
if (result = isRelatedTo(distributiveConstraint, target, reportErrors)) {
resetErrorInfo(saveErrorInfo);
return result;
}
}
const defaultConstraint = getDefaultConstraintOfConditionalType(<ConditionalType>source);
if (defaultConstraint) {
if (result = isRelatedTo(defaultConstraint, target, reportErrors)) {
resetErrorInfo(saveErrorInfo);
return result;
}
}
// conditionals _can_ be related to one another via normal constraint, as, eg, `A extends B ? O : never` should be assignable to `O`
// when `O` is a conditional (`never` is trivially aissgnable to `O`, as is `O`!).
const defaultConstraint = getDefaultConstraintOfConditionalType(<ConditionalType>source);
if (defaultConstraint) {
if (result = isRelatedTo(defaultConstraint, target, reportErrors)) {
resetErrorInfo(saveErrorInfo);
return result;
}
}
}
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196 changes: 110 additions & 86 deletions ...rcularlyConstrainedMappedTypeContainingConditionalNoInfiniteInstantiationDepth.errors.txt
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28 changes: 18 additions & 10 deletions tests/baselines/reference/conditionalTypes1.errors.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -25,14 +25,16 @@ tests/cases/conformance/types/conditional/conditionalTypes1.ts(114,5): error TS2
Type 'string | number | symbol' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
Type 'string' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
tests/cases/conformance/types/conditional/conditionalTypes1.ts(115,5): error TS2322: Type 'T[keyof T] extends Function ? never : keyof T' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
Type 'keyof T' is not assignable to type 'never'.
Type 'string | number | symbol' is not assignable to type 'never'.
Type 'string' is not assignable to type 'never'.
Type 'keyof T' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
Type 'keyof T' is not assignable to type 'never'.
Type 'string | number | symbol' is not assignable to type 'never'.
Type 'string' is not assignable to type 'never'.
tests/cases/conformance/types/conditional/conditionalTypes1.ts(116,5): error TS2322: Type 'keyof T' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
Type 'string | number | symbol' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
Type 'string' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
tests/cases/conformance/types/conditional/conditionalTypes1.ts(117,5): error TS2322: Type 'T[keyof T] extends Function ? keyof T : never' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
Type 'keyof T' is not assignable to type 'never'.
Type 'keyof T' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
Type 'keyof T' is not assignable to type 'never'.
tests/cases/conformance/types/conditional/conditionalTypes1.ts(134,10): error TS2540: Cannot assign to 'id' because it is a read-only property.
tests/cases/conformance/types/conditional/conditionalTypes1.ts(135,5): error TS2542: Index signature in type 'DeepReadonlyArray<Part>' only permits reading.
tests/cases/conformance/types/conditional/conditionalTypes1.ts(136,22): error TS2540: Cannot assign to 'id' because it is a read-only property.
Expand All @@ -52,7 +54,9 @@ tests/cases/conformance/types/conditional/conditionalTypes1.ts(160,5): error TS2
Type 'string' is not assignable to type 'ZeroOf<T>'.
tests/cases/conformance/types/conditional/conditionalTypes1.ts(263,9): error TS2403: Subsequent variable declarations must have the same type. Variable 'z' must be of type 'T1', but here has type 'Foo<T & U>'.
tests/cases/conformance/types/conditional/conditionalTypes1.ts(288,43): error TS2322: Type 'T95<U>' is not assignable to type 'T94<U>'.
Type 'boolean' is not assignable to type 'true'.
Type 'number | boolean' is not assignable to type 'T94<U>'.
Type 'number' is not assignable to type 'T94<U>'.
Type 'boolean' is not assignable to type 'true'.


==== tests/cases/conformance/types/conditional/conditionalTypes1.ts (22 errors) ====
Expand Down Expand Up @@ -210,9 +214,10 @@ tests/cases/conformance/types/conditional/conditionalTypes1.ts(288,43): error TS
y = z; // Error
~
!!! error TS2322: Type 'T[keyof T] extends Function ? never : keyof T' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
!!! error TS2322: Type 'keyof T' is not assignable to type 'never'.
!!! error TS2322: Type 'string | number | symbol' is not assignable to type 'never'.
!!! error TS2322: Type 'string' is not assignable to type 'never'.
!!! error TS2322: Type 'keyof T' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
!!! error TS2322: Type 'keyof T' is not assignable to type 'never'.
!!! error TS2322: Type 'string | number | symbol' is not assignable to type 'never'.
!!! error TS2322: Type 'string' is not assignable to type 'never'.
z = x; // Error
~
!!! error TS2322: Type 'keyof T' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
Expand All @@ -221,7 +226,8 @@ tests/cases/conformance/types/conditional/conditionalTypes1.ts(288,43): error TS
z = y; // Error
~
!!! error TS2322: Type 'T[keyof T] extends Function ? keyof T : never' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
!!! error TS2322: Type 'keyof T' is not assignable to type 'never'.
!!! error TS2322: Type 'keyof T' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
!!! error TS2322: Type 'keyof T' is not assignable to type 'never'.
}

type DeepReadonly<T> =
Expand Down Expand Up @@ -421,7 +427,9 @@ tests/cases/conformance/types/conditional/conditionalTypes1.ts(288,43): error TS
const f45 = <U>(value: T95<U>): T94<U> => value; // Error
~~~~~
!!! error TS2322: Type 'T95<U>' is not assignable to type 'T94<U>'.
!!! error TS2322: Type 'boolean' is not assignable to type 'true'.
!!! error TS2322: Type 'number | boolean' is not assignable to type 'T94<U>'.
!!! error TS2322: Type 'number' is not assignable to type 'T94<U>'.
!!! error TS2322: Type 'boolean' is not assignable to type 'true'.

// Repro from #21863

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54 changes: 32 additions & 22 deletions tests/baselines/reference/conditionalTypes2.errors.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -7,21 +7,26 @@ tests/cases/conformance/types/conditional/conditionalTypes2.ts(19,5): error TS23
tests/cases/conformance/types/conditional/conditionalTypes2.ts(24,5): error TS2322: Type 'Invariant<B>' is not assignable to type 'Invariant<A>'.
Types of property 'foo' are incompatible.
Type 'B extends string ? keyof B : B' is not assignable to type 'A extends string ? keyof A : A'.
Type 'keyof B' is not assignable to type 'keyof A'.
Type 'string | number | symbol' is not assignable to type 'keyof A'.
Type 'string' is not assignable to type 'keyof A'.
Type 'string' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
Type 'keyof B' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
Type 'string | number | symbol' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
Type 'B | keyof B' is not assignable to type 'A extends string ? keyof A : A'.
Type 'B' is not assignable to type 'A extends string ? keyof A : A'.
Type 'A' is not assignable to type 'A extends string ? keyof A : A'.
Type 'keyof B' is not assignable to type 'keyof A'.
Type 'string | number | symbol' is not assignable to type 'keyof A'.
Type 'string' is not assignable to type 'keyof A'.
Type 'string' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
Type 'keyof B' is not assignable to type 'number'.
Type 'string | number | symbol' is not assignable to type 'number'.
Type 'string' is not assignable to type 'number'.
Type 'keyof B' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
Type 'string | number | symbol' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
Type 'string' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
Type 'keyof B' is not assignable to type 'number'.
Type 'string | number | symbol' is not assignable to type 'number'.
Type 'string' is not assignable to type 'number'.
tests/cases/conformance/types/conditional/conditionalTypes2.ts(25,5): error TS2322: Type 'Invariant<A>' is not assignable to type 'Invariant<B>'.
Types of property 'foo' are incompatible.
Type 'A extends string ? keyof A : A' is not assignable to type 'B extends string ? keyof B : B'.
Type 'A' is not assignable to type 'B'.
'B' could be instantiated with an arbitrary type which could be unrelated to 'A'.
Type 'A | keyof A' is not assignable to type 'B extends string ? keyof B : B'.
Type 'A' is not assignable to type 'B extends string ? keyof B : B'.
Type 'A' is not assignable to type 'B'.
'B' could be instantiated with an arbitrary type which could be unrelated to 'A'.
tests/cases/conformance/types/conditional/conditionalTypes2.ts(73,12): error TS2345: Argument of type 'Extract<Extract<T, Foo>, Bar>' is not assignable to parameter of type '{ foo: string; bat: string; }'.
Property 'bat' is missing in type 'Bar & Foo' but required in type '{ foo: string; bat: string; }'.
Type 'Extract<T, Bar>' is not assignable to type '{ foo: string; bat: string; }'.
Expand Down Expand Up @@ -70,23 +75,28 @@ tests/cases/conformance/types/conditional/conditionalTypes2.ts(75,12): error TS2
!!! error TS2322: Type 'Invariant<B>' is not assignable to type 'Invariant<A>'.
!!! error TS2322: Types of property 'foo' are incompatible.
!!! error TS2322: Type 'B extends string ? keyof B : B' is not assignable to type 'A extends string ? keyof A : A'.
!!! error TS2322: Type 'keyof B' is not assignable to type 'keyof A'.
!!! error TS2322: Type 'string | number | symbol' is not assignable to type 'keyof A'.
!!! error TS2322: Type 'string' is not assignable to type 'keyof A'.
!!! error TS2322: Type 'string' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
!!! error TS2322: Type 'keyof B' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
!!! error TS2322: Type 'string | number | symbol' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
!!! error TS2322: Type 'B | keyof B' is not assignable to type 'A extends string ? keyof A : A'.
!!! error TS2322: Type 'B' is not assignable to type 'A extends string ? keyof A : A'.
!!! error TS2322: Type 'A' is not assignable to type 'A extends string ? keyof A : A'.
!!! error TS2322: Type 'keyof B' is not assignable to type 'keyof A'.
!!! error TS2322: Type 'string | number | symbol' is not assignable to type 'keyof A'.
!!! error TS2322: Type 'string' is not assignable to type 'keyof A'.
!!! error TS2322: Type 'string' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
!!! error TS2322: Type 'keyof B' is not assignable to type 'number'.
!!! error TS2322: Type 'string | number | symbol' is not assignable to type 'number'.
!!! error TS2322: Type 'string' is not assignable to type 'number'.
!!! error TS2322: Type 'keyof B' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
!!! error TS2322: Type 'string | number | symbol' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
!!! error TS2322: Type 'string' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
!!! error TS2322: Type 'keyof B' is not assignable to type 'number'.
!!! error TS2322: Type 'string | number | symbol' is not assignable to type 'number'.
!!! error TS2322: Type 'string' is not assignable to type 'number'.
b = a; // Error
~
!!! error TS2322: Type 'Invariant<A>' is not assignable to type 'Invariant<B>'.
!!! error TS2322: Types of property 'foo' are incompatible.
!!! error TS2322: Type 'A extends string ? keyof A : A' is not assignable to type 'B extends string ? keyof B : B'.
!!! error TS2322: Type 'A' is not assignable to type 'B'.
!!! error TS2322: 'B' could be instantiated with an arbitrary type which could be unrelated to 'A'.
!!! error TS2322: Type 'A | keyof A' is not assignable to type 'B extends string ? keyof B : B'.
!!! error TS2322: Type 'A' is not assignable to type 'B extends string ? keyof B : B'.
!!! error TS2322: Type 'A' is not assignable to type 'B'.
!!! error TS2322: 'B' could be instantiated with an arbitrary type which could be unrelated to 'A'.
}

// Extract<T, Function> is a T that is known to be a Function
Expand Down
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