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weswighamweswigham
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Allow intersections (and substitutions) to be checks against discriminable unions (microsoft#36663)
1 parent 70e6f5b commit aece8c0

5 files changed

+126
-3
lines changed

‎src/compiler/checker.ts

+3-3
Original file line numberDiff line numberDiff line change
@@ -15901,7 +15901,7 @@ namespace ts {
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// with respect to T. We do not report errors here, as we will use the existing
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// error result from checking each constituent of the union.
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if (source.flags & (TypeFlags.Object | TypeFlags.Intersection) && target.flags & TypeFlags.Union) {
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const objectOnlyTarget = extractTypesOfKind(target, TypeFlags.Object);
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const objectOnlyTarget = extractTypesOfKind(target, TypeFlags.Object | TypeFlags.Intersection | TypeFlags.Substitution);
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if (objectOnlyTarget.flags & TypeFlags.Union) {
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const result = typeRelatedToDiscriminatedType(source, objectOnlyTarget as UnionType);
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if (result) {
@@ -15998,7 +15998,7 @@ namespace ts {
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// NOTE: See ~/tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithDiscriminatedUnion.ts
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// for examples.
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16001-
const sourceProperties = getPropertiesOfObjectType(source);
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const sourceProperties = getPropertiesOfType(source);
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const sourcePropertiesFiltered = findDiscriminantProperties(sourceProperties, target);
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if (!sourcePropertiesFiltered) return Ternary.False;
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@@ -16037,7 +16037,7 @@ namespace ts {
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outer: for (const type of target.types) {
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for (let i = 0; i < sourcePropertiesFiltered.length; i++) {
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const sourceProperty = sourcePropertiesFiltered[i];
16040-
const targetProperty = getPropertyOfObjectType(type, sourceProperty.escapedName);
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const targetProperty = getPropertyOfType(type, sourceProperty.escapedName);
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if (!targetProperty) continue outer;
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if (sourceProperty === targetProperty) continue;
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// We compare the source property to the target in the context of a single discriminant type.

‎tests/baselines/reference/discriminableUnionWithIntersectedMembers.js

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@@ -0,0 +1,21 @@
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//// [discriminableUnionWithIntersectedMembers.ts]
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// regression test for https://github.com/microsoft/TypeScript/issues/33243
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type X =
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| { x: 'x', y: number } & { y: number }
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| { x: 'y', y: number, z?: boolean } & { y: number }
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// error
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const x: X = 4 as any as { x: 'x' | 'y', y: number };
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type Y =
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| { x: 'x', y: number }
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| { x: 'y', y: number, z?: boolean }
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// no error
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const y: Y = 4 as any as { x: 'x' | 'y', y: number };
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//// [discriminableUnionWithIntersectedMembers.js]
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// error
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var x = 4;
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// no error
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var y = 4;

‎tests/baselines/reference/discriminableUnionWithIntersectedMembers.symbols

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@@ -0,0 +1,42 @@
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=== tests/cases/compiler/discriminableUnionWithIntersectedMembers.ts ===
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// regression test for https://github.com/microsoft/TypeScript/issues/33243
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type X =
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>X : Symbol(X, Decl(discriminableUnionWithIntersectedMembers.ts, 0, 0))
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| { x: 'x', y: number } & { y: number }
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>x : Symbol(x, Decl(discriminableUnionWithIntersectedMembers.ts, 2, 4))
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>y : Symbol(y, Decl(discriminableUnionWithIntersectedMembers.ts, 2, 12))
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>y : Symbol(y, Decl(discriminableUnionWithIntersectedMembers.ts, 2, 28))
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| { x: 'y', y: number, z?: boolean } & { y: number }
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>x : Symbol(x, Decl(discriminableUnionWithIntersectedMembers.ts, 3, 4))
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>y : Symbol(y, Decl(discriminableUnionWithIntersectedMembers.ts, 3, 12))
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>z : Symbol(z, Decl(discriminableUnionWithIntersectedMembers.ts, 3, 23))
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>y : Symbol(y, Decl(discriminableUnionWithIntersectedMembers.ts, 3, 41))
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// error
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const x: X = 4 as any as { x: 'x' | 'y', y: number };
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>x : Symbol(x, Decl(discriminableUnionWithIntersectedMembers.ts, 6, 5))
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>X : Symbol(X, Decl(discriminableUnionWithIntersectedMembers.ts, 0, 0))
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>x : Symbol(x, Decl(discriminableUnionWithIntersectedMembers.ts, 6, 26))
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>y : Symbol(y, Decl(discriminableUnionWithIntersectedMembers.ts, 6, 40))
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type Y =
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>Y : Symbol(Y, Decl(discriminableUnionWithIntersectedMembers.ts, 6, 53))
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| { x: 'x', y: number }
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>x : Symbol(x, Decl(discriminableUnionWithIntersectedMembers.ts, 9, 4))
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>y : Symbol(y, Decl(discriminableUnionWithIntersectedMembers.ts, 9, 12))
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| { x: 'y', y: number, z?: boolean }
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>x : Symbol(x, Decl(discriminableUnionWithIntersectedMembers.ts, 10, 4))
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>y : Symbol(y, Decl(discriminableUnionWithIntersectedMembers.ts, 10, 12))
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>z : Symbol(z, Decl(discriminableUnionWithIntersectedMembers.ts, 10, 23))
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// no error
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const y: Y = 4 as any as { x: 'x' | 'y', y: number };
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>y : Symbol(y, Decl(discriminableUnionWithIntersectedMembers.ts, 13, 5))
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>Y : Symbol(Y, Decl(discriminableUnionWithIntersectedMembers.ts, 6, 53))
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>x : Symbol(x, Decl(discriminableUnionWithIntersectedMembers.ts, 13, 26))
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>y : Symbol(y, Decl(discriminableUnionWithIntersectedMembers.ts, 13, 40))
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‎tests/baselines/reference/discriminableUnionWithIntersectedMembers.types

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@@ -0,0 +1,46 @@
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=== tests/cases/compiler/discriminableUnionWithIntersectedMembers.ts ===
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// regression test for https://github.com/microsoft/TypeScript/issues/33243
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type X =
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>X : X
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| { x: 'x', y: number } & { y: number }
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>x : "x"
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>y : number
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>y : number
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| { x: 'y', y: number, z?: boolean } & { y: number }
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>x : "y"
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>y : number
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>z : boolean
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>y : number
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// error
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const x: X = 4 as any as { x: 'x' | 'y', y: number };
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>x : X
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>4 as any as { x: 'x' | 'y', y: number } : { x: "x" | "y"; y: number; }
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>4 as any : any
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>4 : 4
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>x : "x" | "y"
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>y : number
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type Y =
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>Y : Y
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| { x: 'x', y: number }
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>x : "x"
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>y : number
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| { x: 'y', y: number, z?: boolean }
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>x : "y"
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>y : number
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>z : boolean
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// no error
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const y: Y = 4 as any as { x: 'x' | 'y', y: number };
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>y : Y
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>4 as any as { x: 'x' | 'y', y: number } : { x: "x" | "y"; y: number; }
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>4 as any : any
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>4 : 4
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>x : "x" | "y"
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>y : number
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‎tests/cases/compiler/discriminableUnionWithIntersectedMembers.ts

+14
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@@ -0,0 +1,14 @@
1+
// regression test for https://github.com/microsoft/TypeScript/issues/33243
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type X =
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| { x: 'x', y: number } & { y: number }
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| { x: 'y', y: number, z?: boolean } & { y: number }
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// error
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const x: X = 4 as any as { x: 'x' | 'y', y: number };
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type Y =
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| { x: 'x', y: number }
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| { x: 'y', y: number, z?: boolean }
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// no error
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const y: Y = 4 as any as { x: 'x' | 'y', y: number };

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