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Improve type discrimination algorithm (#1085)
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7 files changed

+219
-26
lines changed

7 files changed

+219
-26
lines changed

‎internal/checker/relater.go

Lines changed: 6 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1217,10 +1217,12 @@ func (c *Checker) discriminateTypeByDiscriminableItems(target *Type, discriminat
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for i := range types {
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if include[i] != TernaryFalse {
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targetType := c.getTypeOfPropertyOrIndexSignatureOfType(types[i], discriminator.name(n))
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if targetType != nil && discriminator.matches(n, targetType) {
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matched = true
1222-
} else {
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include[i] = TernaryMaybe
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if targetType != nil {
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if discriminator.matches(n, targetType) {
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matched = true
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} else {
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include[i] = TernaryMaybe
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}
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}
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}
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}

‎testdata/baselines/reference/compiler/missingDiscriminants.errors.txt

Lines changed: 28 additions & 0 deletions
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missingDiscriminants.ts(17,23): error TS2353: Object literal may only specify known properties, and 'subkind' does not exist in type '{ kind: "b"; }'.
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missingDiscriminants.ts(18,34): error TS2353: Object literal may only specify known properties, and 'subkind' does not exist in type '{ kind: "b"; }'.
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==== missingDiscriminants.ts (2 errors) ====
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// https://github.com/microsoft/typescript-go/issues/1020
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type Thing =
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| { str: "a", num: 0 }
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| { str: "b" }
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| { num: 1 }
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const thing1: Thing = { str: "a", num: 0 }
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const thing2: Thing = { str: "b", num: 1 } // Shouldn't be error
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const thing3: Thing = { num: 1, str: "b" } // Shouldn't be error
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type Item =
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| { kind: "a", subkind: 0, value: string }
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| { kind: "a", subkind: 1, value: number }
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| { kind: "b" }
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const item1: Item = { subkind: 1, kind: "b" } // Error, type "b" not assignable to type "a"
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~~~~~~~
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!!! error TS2353: Object literal may only specify known properties, and 'subkind' does not exist in type '{ kind: "b"; }'.
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const item2: Item = { kind: "b", subkind: 1 } // Error, 'subkind' isn't a known property
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~~~~~~~
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!!! error TS2353: Object literal may only specify known properties, and 'subkind' does not exist in type '{ kind: "b"; }'.
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‎testdata/baselines/reference/compiler/missingDiscriminants.symbols

Lines changed: 64 additions & 0 deletions
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@@ -0,0 +1,64 @@
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//// [tests/cases/compiler/missingDiscriminants.ts] ////
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=== missingDiscriminants.ts ===
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// https://github.com/microsoft/typescript-go/issues/1020
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type Thing =
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>Thing : Symbol(Thing, Decl(missingDiscriminants.ts, 0, 0))
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| { str: "a", num: 0 }
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>str : Symbol(str, Decl(missingDiscriminants.ts, 3, 5))
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>num : Symbol(num, Decl(missingDiscriminants.ts, 3, 15))
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| { str: "b" }
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>str : Symbol(str, Decl(missingDiscriminants.ts, 4, 5))
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| { num: 1 }
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>num : Symbol(num, Decl(missingDiscriminants.ts, 5, 5))
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const thing1: Thing = { str: "a", num: 0 }
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>thing1 : Symbol(thing1, Decl(missingDiscriminants.ts, 7, 5))
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>Thing : Symbol(Thing, Decl(missingDiscriminants.ts, 0, 0))
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>str : Symbol(str, Decl(missingDiscriminants.ts, 7, 23))
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>num : Symbol(num, Decl(missingDiscriminants.ts, 7, 33))
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const thing2: Thing = { str: "b", num: 1 } // Shouldn't be error
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>thing2 : Symbol(thing2, Decl(missingDiscriminants.ts, 8, 5))
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>Thing : Symbol(Thing, Decl(missingDiscriminants.ts, 0, 0))
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>str : Symbol(str, Decl(missingDiscriminants.ts, 8, 23))
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>num : Symbol(num, Decl(missingDiscriminants.ts, 8, 33))
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const thing3: Thing = { num: 1, str: "b" } // Shouldn't be error
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>thing3 : Symbol(thing3, Decl(missingDiscriminants.ts, 9, 5))
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>Thing : Symbol(Thing, Decl(missingDiscriminants.ts, 0, 0))
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>num : Symbol(num, Decl(missingDiscriminants.ts, 9, 23))
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>str : Symbol(str, Decl(missingDiscriminants.ts, 9, 31))
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type Item =
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>Item : Symbol(Item, Decl(missingDiscriminants.ts, 9, 42))
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| { kind: "a", subkind: 0, value: string }
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>kind : Symbol(kind, Decl(missingDiscriminants.ts, 12, 5))
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>subkind : Symbol(subkind, Decl(missingDiscriminants.ts, 12, 16))
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>value : Symbol(value, Decl(missingDiscriminants.ts, 12, 28))
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| { kind: "a", subkind: 1, value: number }
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>kind : Symbol(kind, Decl(missingDiscriminants.ts, 13, 5))
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>subkind : Symbol(subkind, Decl(missingDiscriminants.ts, 13, 16))
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>value : Symbol(value, Decl(missingDiscriminants.ts, 13, 28))
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| { kind: "b" }
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>kind : Symbol(kind, Decl(missingDiscriminants.ts, 14, 5))
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const item1: Item = { subkind: 1, kind: "b" } // Error, type "b" not assignable to type "a"
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>item1 : Symbol(item1, Decl(missingDiscriminants.ts, 16, 5))
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>Item : Symbol(Item, Decl(missingDiscriminants.ts, 9, 42))
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>subkind : Symbol(subkind, Decl(missingDiscriminants.ts, 16, 21))
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>kind : Symbol(kind, Decl(missingDiscriminants.ts, 16, 33))
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const item2: Item = { kind: "b", subkind: 1 } // Error, 'subkind' isn't a known property
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>item2 : Symbol(item2, Decl(missingDiscriminants.ts, 17, 5))
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>Item : Symbol(Item, Decl(missingDiscriminants.ts, 9, 42))
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>kind : Symbol(kind, Decl(missingDiscriminants.ts, 17, 21))
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>subkind : Symbol(subkind, Decl(missingDiscriminants.ts, 17, 32))
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‎testdata/baselines/reference/compiler/missingDiscriminants.types

Lines changed: 74 additions & 0 deletions
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//// [tests/cases/compiler/missingDiscriminants.ts] ////
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=== missingDiscriminants.ts ===
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// https://github.com/microsoft/typescript-go/issues/1020
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type Thing =
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>Thing : Thing
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| { str: "a", num: 0 }
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>str : "a"
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>num : 0
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| { str: "b" }
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>str : "b"
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| { num: 1 }
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>num : 1
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const thing1: Thing = { str: "a", num: 0 }
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>thing1 : Thing
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>{ str: "a", num: 0 } : { str: "a"; num: 0; }
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>str : "a"
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>"a" : "a"
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>num : 0
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>0 : 0
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const thing2: Thing = { str: "b", num: 1 } // Shouldn't be error
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>thing2 : Thing
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>{ str: "b", num: 1 } : { str: "b"; num: 1; }
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>str : "b"
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>"b" : "b"
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>num : 1
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>1 : 1
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const thing3: Thing = { num: 1, str: "b" } // Shouldn't be error
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>thing3 : Thing
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>{ num: 1, str: "b" } : { num: 1; str: "b"; }
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>num : 1
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>1 : 1
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>str : "b"
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>"b" : "b"
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type Item =
44+
>Item : Item
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| { kind: "a", subkind: 0, value: string }
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>kind : "a"
48+
>subkind : 0
49+
>value : string
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| { kind: "a", subkind: 1, value: number }
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>kind : "a"
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>subkind : 1
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>value : number
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| { kind: "b" }
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>kind : "b"
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const item1: Item = { subkind: 1, kind: "b" } // Error, type "b" not assignable to type "a"
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>item1 : Item
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>{ subkind: 1, kind: "b" } : { subkind: number; kind: "b"; }
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>subkind : number
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>1 : 1
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>kind : "b"
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>"b" : "b"
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const item2: Item = { kind: "b", subkind: 1 } // Error, 'subkind' isn't a known property
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>item2 : Item
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>{ kind: "b", subkind: 1 } : { kind: "b"; subkind: number; }
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>kind : "b"
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>"b" : "b"
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>subkind : number
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>1 : 1
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‎testdata/baselines/reference/submodule/compiler/discriminateWithMissingProperty.errors.txt

Lines changed: 0 additions & 22 deletions
This file was deleted.

‎testdata/baselines/reference/submodule/compiler/discriminateWithMissingProperty.errors.txt.diff

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--- old.discriminateWithMissingProperty.errors.txt
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+++ new.discriminateWithMissingProperty.errors.txt
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@@= skipped -0, +0 lines =@@
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-discriminateWithMissingProperty.ts(12,5): error TS2345: Argument of type '{ mode: "numeric"; data: Uint8Array<ArrayBuffer>; }' is not assignable to parameter of type 'Arg'.
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- Types of property 'data' are incompatible.
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- Type 'Uint8Array<ArrayBuffer>' is not assignable to type 'number'.
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-
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-
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-==== discriminateWithMissingProperty.ts (1 errors) ====
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- type Arg = {
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- mode: "numeric",
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- data: number,
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- } | {
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- mode: "alphabetic",
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- data: string,
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- } | {
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- data: string | Uint8Array;
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- }
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-
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- declare function foo(arg: Arg): void;
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- foo({ mode: "numeric", data: new Uint8Array([30]) }); // Should error
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- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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-!!! error TS2345: Argument of type '{ mode: "numeric"; data: Uint8Array<ArrayBuffer>; }' is not assignable to parameter of type 'Arg'.
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-!!! error TS2345: Types of property 'data' are incompatible.
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-!!! error TS2345: Type 'Uint8Array<ArrayBuffer>' is not assignable to type 'number'.
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+<no content>

‎testdata/tests/cases/compiler/missingDiscriminants.ts

Lines changed: 21 additions & 0 deletions
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// @strict: true
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// @noEmit: true
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// https://github.com/microsoft/typescript-go/issues/1020
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type Thing =
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| { str: "a", num: 0 }
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| { str: "b" }
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| { num: 1 }
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const thing1: Thing = { str: "a", num: 0 }
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const thing2: Thing = { str: "b", num: 1 } // Shouldn't be error
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const thing3: Thing = { num: 1, str: "b" } // Shouldn't be error
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type Item =
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| { kind: "a", subkind: 0, value: string }
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| { kind: "a", subkind: 1, value: number }
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| { kind: "b" }
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const item1: Item = { subkind: 1, kind: "b" } // Error, type "b" not assignable to type "a"
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const item2: Item = { kind: "b", subkind: 1 } // Error, 'subkind' isn't a known property

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