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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.
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7 files changed

+149
-2
lines changed

7 files changed

+149
-2
lines changed

‎src/compiler/checker.ts‎

Lines changed: 6 additions & 2 deletions
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 {
1740817408
if (targetType.flags & TypeFlags.Object) {
17409-
const resolved = resolveStructuredTypeMembers(<ObjectType>targetType);
17409+
const resolved = resolveStructuredTypeMembers(targetType as ObjectType);
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if (resolved.stringIndexInfo ||
1741117411
resolved.numberIndexInfo && isNumericLiteralName(name) ||
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getPropertyOfObjectType(targetType, name) ||
@@ -17416,12 +17416,16 @@ namespace ts {
1741617416
}
1741717417
}
1741817418
else if (targetType.flags & TypeFlags.UnionOrIntersection) {
17419-
for (const t of (<UnionOrIntersectionType>targetType).types) {
17419+
for (const t of (targetType as UnionOrIntersectionType).types) {
1742017420
if (isKnownProperty(t, name, isComparingJsxAttributes)) {
1742117421
return true;
1742217422
}
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}
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}
17425+
else if (targetType.flags & TypeFlags.Conditional) {
17426+
return isKnownProperty((targetType as ConditionalType).root.trueType, name, isComparingJsxAttributes) ||
17427+
isKnownProperty((targetType as ConditionalType).root.falseType, name, isComparingJsxAttributes);
17428+
}
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return false;
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}
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‎src/compiler/core.ts‎

Lines changed: 3 additions & 0 deletions
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) {
18671867
const candidateNameLowerCase = candidateName.toLowerCase();
18681868
if (candidateNameLowerCase === nameLowerCase) {
1869+
if (candidateName === name) {
1870+
continue;
1871+
}
18691872
return candidate;
18701873
}
18711874
if (justCheckExactMatches) {

‎tests/baselines/reference/conditionalTypesExcessProperties.errors.txt‎

Lines changed: 24 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,24 @@
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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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==== 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

Lines changed: 18 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,18 @@
1+
//// [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>) {
9+
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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}
12+
13+
14+
//// [conditionalTypesExcessProperties.js]
15+
function testFunc2(a, sa) {
16+
sa = { test: 'hi', arg: a }; // not excess (but currently still not assignable)
17+
sa = { test: 'bye', arg: a, arr: a }; // excess
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}

‎tests/baselines/reference/conditionalTypesExcessProperties.symbols‎

Lines changed: 41 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -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))
4+
>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))
7+
8+
arg: T
9+
>arg : Symbol(arg, Decl(conditionalTypesExcessProperties.ts, 0, 61))
10+
>T : Symbol(T, Decl(conditionalTypesExcessProperties.ts, 0, 15))
11+
12+
} : {
13+
arg?: undefined
14+
>arg : Symbol(arg, Decl(conditionalTypesExcessProperties.ts, 2, 5))
15+
16+
});
17+
18+
function testFunc2<A extends object>(a: A, sa: Something<A>) {
19+
>testFunc2 : Symbol(testFunc2, Decl(conditionalTypesExcessProperties.ts, 4, 7))
20+
>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))
26+
27+
sa = { test: 'hi', arg: a }; // not excess (but currently still not assignable)
28+
>sa : Symbol(sa, Decl(conditionalTypesExcessProperties.ts, 6, 42))
29+
>test : Symbol(test, Decl(conditionalTypesExcessProperties.ts, 7, 10))
30+
>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))
35+
>test : Symbol(test, Decl(conditionalTypesExcessProperties.ts, 8, 10))
36+
>arg : Symbol(arg, Decl(conditionalTypesExcessProperties.ts, 8, 23))
37+
>a : Symbol(a, Decl(conditionalTypesExcessProperties.ts, 6, 37))
38+
>arr : Symbol(arr, Decl(conditionalTypesExcessProperties.ts, 8, 31))
39+
>a : Symbol(a, Decl(conditionalTypesExcessProperties.ts, 6, 37))
40+
}
41+

‎tests/baselines/reference/conditionalTypesExcessProperties.types‎

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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
23+
>sa : Something<A>
24+
>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>
30+
>{ test: 'hi', arg: a } : { test: string; arg: A; }
31+
>test : string
32+
>'hi' : "hi"
33+
>arg : A
34+
>a : A
35+
36+
sa = { test: 'bye', arg: a, arr: a } // excess
37+
>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
45+
>a : A
46+
}
47+

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

Lines changed: 10 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -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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