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Use bidirectional comparability (aka comparability) in narrowing

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Andrew Branch
2022-09-01 10:37:43 -07:00
parent 19defbfe57
commit 46ce0b2582
5 changed files with 99 additions and 1 deletions
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src/compiler/checker.ts
+1 -1
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@@ -25096,7 +25096,7 @@ namespace ts {
const narrowedPropType = narrowType(propType);
return filterType(type, t => {
const discriminantType = getTypeOfPropertyOrIndexSignature(t, propName);
return !(narrowedPropType.flags & TypeFlags.Never) && isTypeComparableTo(narrowedPropType, discriminantType);
return !(narrowedPropType.flags & TypeFlags.Never) && areTypesComparable(narrowedPropType, discriminantType);
});
}
tests/baselines/reference/50527.js
+19
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@@ -0,0 +1,19 @@
//// [50527.ts]
type S =
| { type: 'string', value: string }
| { type: 'number', value: number }
| { type: 'unknown', value: unknown }
| { value: undefined };
declare var s: S
if (s.value !== undefined) {
s;
}
//// [50527.js]
"use strict";
if (s.value !== undefined) {
s;
}
tests/baselines/reference/50527.symbols
+33
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@@ -0,0 +1,33 @@
=== tests/cases/compiler/50527.ts ===
type S =
>S : Symbol(S, Decl(50527.ts, 0, 0))
| { type: 'string', value: string }
>type : Symbol(type, Decl(50527.ts, 1, 3))
>value : Symbol(value, Decl(50527.ts, 1, 19))
| { type: 'number', value: number }
>type : Symbol(type, Decl(50527.ts, 2, 3))
>value : Symbol(value, Decl(50527.ts, 2, 19))
| { type: 'unknown', value: unknown }
>type : Symbol(type, Decl(50527.ts, 3, 3))
>value : Symbol(value, Decl(50527.ts, 3, 20))
| { value: undefined };
>value : Symbol(value, Decl(50527.ts, 4, 3))
declare var s: S
>s : Symbol(s, Decl(50527.ts, 6, 11))
>S : Symbol(S, Decl(50527.ts, 0, 0))
if (s.value !== undefined) {
>s.value : Symbol(value, Decl(50527.ts, 1, 19), Decl(50527.ts, 2, 19), Decl(50527.ts, 3, 20), Decl(50527.ts, 4, 3))
>s : Symbol(s, Decl(50527.ts, 6, 11))
>value : Symbol(value, Decl(50527.ts, 1, 19), Decl(50527.ts, 2, 19), Decl(50527.ts, 3, 20), Decl(50527.ts, 4, 3))
>undefined : Symbol(undefined)
s;
>s : Symbol(s, Decl(50527.ts, 6, 11))
}
tests/baselines/reference/50527.types
+33
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@@ -0,0 +1,33 @@
=== tests/cases/compiler/50527.ts ===
type S =
>S : { type: 'string'; value: string; } | { type: 'number'; value: number; } | { type: 'unknown'; value: unknown; } | { value: undefined; }
| { type: 'string', value: string }
>type : "string"
>value : string
| { type: 'number', value: number }
>type : "number"
>value : number
| { type: 'unknown', value: unknown }
>type : "unknown"
>value : unknown
| { value: undefined };
>value : undefined
declare var s: S
>s : S
if (s.value !== undefined) {
>s.value !== undefined : boolean
>s.value : unknown
>s : S
>value : unknown
>undefined : undefined
s;
>s : { type: "string"; value: string; } | { type: "number"; value: number; } | { type: "unknown"; value: unknown; }
}
tests/cases/compiler/50527.ts
+13
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@@ -0,0 +1,13 @@
// @strict: true
type S =
| { type: 'string', value: string }
| { type: 'number', value: number }
| { type: 'unknown', value: unknown }
| { value: undefined };
declare var s: S
if (s.value !== undefined) {
s;
}