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sandersnsandersn
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Excess property understands conditional types (#25584)
Previously it did not, causing misleading excess property errors. Note that assignability errors with conditional types are still usually confusing. This PR doesn't address that. Also, make sure that exact matches in getSpellingSuggestion are skipped.
1 parent 52486ae commit 42a2d9e

7 files changed

+149
-2
lines changed

‎src/compiler/checker.ts

+6-2
Original file line numberDiff line numberDiff line change
@@ -17406,7 +17406,7 @@ namespace ts {
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*/
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function isKnownProperty(targetType: Type, name: __String, isComparingJsxAttributes: boolean): boolean {
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if (targetType.flags & TypeFlags.Object) {
17409-
const resolved = resolveStructuredTypeMembers(<ObjectType>targetType);
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const resolved = resolveStructuredTypeMembers(targetType as ObjectType);
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if (resolved.stringIndexInfo ||
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resolved.numberIndexInfo && isNumericLiteralName(name) ||
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getPropertyOfObjectType(targetType, name) ||
@@ -17416,12 +17416,16 @@ namespace ts {
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}
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}
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else if (targetType.flags & TypeFlags.UnionOrIntersection) {
17419-
for (const t of (<UnionOrIntersectionType>targetType).types) {
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for (const t of (targetType as UnionOrIntersectionType).types) {
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if (isKnownProperty(t, name, isComparingJsxAttributes)) {
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return true;
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}
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}
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}
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else if (targetType.flags & TypeFlags.Conditional) {
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return isKnownProperty((targetType as ConditionalType).root.trueType, name, isComparingJsxAttributes) ||
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isKnownProperty((targetType as ConditionalType).root.falseType, name, isComparingJsxAttributes);
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}
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return false;
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}
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‎src/compiler/core.ts

+3
Original file line numberDiff line numberDiff line change
@@ -1866,6 +1866,9 @@ namespace ts {
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if (candidateName !== undefined && Math.abs(candidateName.length - nameLowerCase.length) <= maximumLengthDifference) {
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const candidateNameLowerCase = candidateName.toLowerCase();
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if (candidateNameLowerCase === nameLowerCase) {
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if (candidateName === name) {
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continue;
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}
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return candidate;
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}
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if (justCheckExactMatches) {

‎tests/baselines/reference/conditionalTypesExcessProperties.errors.txt

+24
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@@ -0,0 +1,24 @@
1+
tests/cases/conformance/types/conditional/conditionalTypesExcessProperties.ts(8,5): error TS2322: Type '{ test: string; arg: A; }' is not assignable to type 'Something<A>'.
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Type '{ test: string; arg: A; }' is not assignable to type 'A extends object ? { arg: A; } : { arg?: undefined; }'.
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tests/cases/conformance/types/conditional/conditionalTypesExcessProperties.ts(9,33): error TS2322: Type 'A' is not assignable to type 'Something<A>["arr"]'.
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Type 'object' is not assignable to type 'Something<A>["arr"]'.
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6+
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==== tests/cases/conformance/types/conditional/conditionalTypesExcessProperties.ts (2 errors) ====
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type Something<T> = { test: string } & (T extends object ? {
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arg: T
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} : {
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arg?: undefined
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});
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function testFunc2<A extends object>(a: A, sa: Something<A>) {
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sa = { test: 'hi', arg: a }; // not excess (but currently still not assignable)
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~~
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!!! error TS2322: Type '{ test: string; arg: A; }' is not assignable to type 'Something<A>'.
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!!! error TS2322: Type '{ test: string; arg: A; }' is not assignable to type 'A extends object ? { arg: A; } : { arg?: undefined; }'.
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sa = { test: 'bye', arg: a, arr: a } // excess
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~~~
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!!! error TS2322: Type 'A' is not assignable to type 'Something<A>["arr"]'.
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!!! error TS2322: Type 'object' is not assignable to type 'Something<A>["arr"]'.
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}
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‎tests/baselines/reference/conditionalTypesExcessProperties.js

+18
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,18 @@
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//// [conditionalTypesExcessProperties.ts]
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type Something<T> = { test: string } & (T extends object ? {
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arg: T
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} : {
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arg?: undefined
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});
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function testFunc2<A extends object>(a: A, sa: Something<A>) {
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sa = { test: 'hi', arg: a }; // not excess (but currently still not assignable)
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sa = { test: 'bye', arg: a, arr: a } // excess
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}
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13+
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//// [conditionalTypesExcessProperties.js]
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function testFunc2(a, sa) {
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sa = { test: 'hi', arg: a }; // not excess (but currently still not assignable)
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sa = { test: 'bye', arg: a, arr: a }; // excess
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}

‎tests/baselines/reference/conditionalTypesExcessProperties.symbols

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@@ -0,0 +1,41 @@
1+
=== tests/cases/conformance/types/conditional/conditionalTypesExcessProperties.ts ===
2+
type Something<T> = { test: string } & (T extends object ? {
3+
>Something : Symbol(Something, Decl(conditionalTypesExcessProperties.ts, 0, 0))
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>T : Symbol(T, Decl(conditionalTypesExcessProperties.ts, 0, 15))
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>test : Symbol(test, Decl(conditionalTypesExcessProperties.ts, 0, 21))
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>T : Symbol(T, Decl(conditionalTypesExcessProperties.ts, 0, 15))
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arg: T
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>arg : Symbol(arg, Decl(conditionalTypesExcessProperties.ts, 0, 61))
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>T : Symbol(T, Decl(conditionalTypesExcessProperties.ts, 0, 15))
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12+
} : {
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arg?: undefined
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>arg : Symbol(arg, Decl(conditionalTypesExcessProperties.ts, 2, 5))
15+
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});
17+
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function testFunc2<A extends object>(a: A, sa: Something<A>) {
19+
>testFunc2 : Symbol(testFunc2, Decl(conditionalTypesExcessProperties.ts, 4, 7))
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>A : Symbol(A, Decl(conditionalTypesExcessProperties.ts, 6, 19))
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>a : Symbol(a, Decl(conditionalTypesExcessProperties.ts, 6, 37))
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>A : Symbol(A, Decl(conditionalTypesExcessProperties.ts, 6, 19))
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>sa : Symbol(sa, Decl(conditionalTypesExcessProperties.ts, 6, 42))
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>Something : Symbol(Something, Decl(conditionalTypesExcessProperties.ts, 0, 0))
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>A : Symbol(A, Decl(conditionalTypesExcessProperties.ts, 6, 19))
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sa = { test: 'hi', arg: a }; // not excess (but currently still not assignable)
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>sa : Symbol(sa, Decl(conditionalTypesExcessProperties.ts, 6, 42))
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>test : Symbol(test, Decl(conditionalTypesExcessProperties.ts, 7, 10))
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>arg : Symbol(arg, Decl(conditionalTypesExcessProperties.ts, 7, 22))
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>a : Symbol(a, Decl(conditionalTypesExcessProperties.ts, 6, 37))
32+
33+
sa = { test: 'bye', arg: a, arr: a } // excess
34+
>sa : Symbol(sa, Decl(conditionalTypesExcessProperties.ts, 6, 42))
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>test : Symbol(test, Decl(conditionalTypesExcessProperties.ts, 8, 10))
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>arg : Symbol(arg, Decl(conditionalTypesExcessProperties.ts, 8, 23))
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>a : Symbol(a, Decl(conditionalTypesExcessProperties.ts, 6, 37))
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>arr : Symbol(arr, Decl(conditionalTypesExcessProperties.ts, 8, 31))
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>a : Symbol(a, Decl(conditionalTypesExcessProperties.ts, 6, 37))
40+
}
41+

‎tests/baselines/reference/conditionalTypesExcessProperties.types

+47
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@@ -0,0 +1,47 @@
1+
=== tests/cases/conformance/types/conditional/conditionalTypesExcessProperties.ts ===
2+
type Something<T> = { test: string } & (T extends object ? {
3+
>Something : Something<T>
4+
>T : T
5+
>test : string
6+
>T : T
7+
8+
arg: T
9+
>arg : T
10+
>T : T
11+
12+
} : {
13+
arg?: undefined
14+
>arg : undefined
15+
16+
});
17+
18+
function testFunc2<A extends object>(a: A, sa: Something<A>) {
19+
>testFunc2 : <A extends object>(a: A, sa: Something<A>) => void
20+
>A : A
21+
>a : A
22+
>A : A
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>sa : Something<A>
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>Something : Something<T>
25+
>A : A
26+
27+
sa = { test: 'hi', arg: a }; // not excess (but currently still not assignable)
28+
>sa = { test: 'hi', arg: a } : { test: string; arg: A; }
29+
>sa : Something<A>
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>{ test: 'hi', arg: a } : { test: string; arg: A; }
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>test : string
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>'hi' : "hi"
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>arg : A
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>a : A
35+
36+
sa = { test: 'bye', arg: a, arr: a } // excess
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>sa = { test: 'bye', arg: a, arr: a } : { test: string; arg: A; arr: A; }
38+
>sa : Something<A>
39+
>{ test: 'bye', arg: a, arr: a } : { test: string; arg: A; arr: A; }
40+
>test : string
41+
>'bye' : "bye"
42+
>arg : A
43+
>a : A
44+
>arr : A
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>a : A
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}
47+

‎tests/cases/conformance/types/conditional/conditionalTypesExcessProperties.ts

+10
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@@ -0,0 +1,10 @@
1+
type Something<T> = { test: string } & (T extends object ? {
2+
arg: T
3+
} : {
4+
arg?: undefined
5+
});
6+
7+
function testFunc2<A extends object>(a: A, sa: Something<A>) {
8+
sa = { test: 'hi', arg: a }; // not excess (but currently still not assignable)
9+
sa = { test: 'bye', arg: a, arr: a } // excess
10+
}

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