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AndaristAndarist
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Improve unknown narrowing by negated type predicates (#60795)
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4 files changed

+264
-1
lines changed

4 files changed

+264
-1
lines changed

Diff for: ‎src/compiler/checker.ts

+2-1
Original file line numberDiff line numberDiff line change
@@ -29404,8 +29404,9 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
2940429404
if (checkDerived) {
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return filterType(type, t => !isTypeDerivedFrom(t, candidate));
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}
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type = type.flags & TypeFlags.Unknown ? unknownUnionType : type;
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const trueType = getNarrowedType(type, candidate, /*assumeTrue*/ true, /*checkDerived*/ false);
29408-
return filterType(type, t => !isTypeSubsetOf(t, trueType));
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return recombineUnknownType(filterType(type, t => !isTypeSubsetOf(t, trueType)));
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}
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if (type.flags & TypeFlags.AnyOrUnknown) {
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return candidate;

Diff for: ‎tests/baselines/reference/narrowUnknownByTypePredicate.symbols

+89
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,89 @@
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//// [tests/cases/compiler/narrowUnknownByTypePredicate.ts] ////
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=== narrowUnknownByTypePredicate.ts ===
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declare function isNotNullish(value: unknown): value is {};
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>isNotNullish : Symbol(isNotNullish, Decl(narrowUnknownByTypePredicate.ts, 0, 0))
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>value : Symbol(value, Decl(narrowUnknownByTypePredicate.ts, 0, 30))
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>value : Symbol(value, Decl(narrowUnknownByTypePredicate.ts, 0, 30))
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declare function isNullish(value: unknown): value is null | undefined;
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>isNullish : Symbol(isNullish, Decl(narrowUnknownByTypePredicate.ts, 0, 59))
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>value : Symbol(value, Decl(narrowUnknownByTypePredicate.ts, 1, 27))
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>value : Symbol(value, Decl(narrowUnknownByTypePredicate.ts, 1, 27))
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declare const value1: unknown;
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>value1 : Symbol(value1, Decl(narrowUnknownByTypePredicate.ts, 3, 13))
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if (isNotNullish(value1)) {
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>isNotNullish : Symbol(isNotNullish, Decl(narrowUnknownByTypePredicate.ts, 0, 0))
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>value1 : Symbol(value1, Decl(narrowUnknownByTypePredicate.ts, 3, 13))
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value1;
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>value1 : Symbol(value1, Decl(narrowUnknownByTypePredicate.ts, 3, 13))
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}
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declare const value2: unknown;
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>value2 : Symbol(value2, Decl(narrowUnknownByTypePredicate.ts, 8, 13))
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if (!isNotNullish(value2)) {
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>isNotNullish : Symbol(isNotNullish, Decl(narrowUnknownByTypePredicate.ts, 0, 0))
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>value2 : Symbol(value2, Decl(narrowUnknownByTypePredicate.ts, 8, 13))
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value2;
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>value2 : Symbol(value2, Decl(narrowUnknownByTypePredicate.ts, 8, 13))
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}
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declare const value3: unknown;
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>value3 : Symbol(value3, Decl(narrowUnknownByTypePredicate.ts, 13, 13))
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if (isNullish(value3)) {
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>isNullish : Symbol(isNullish, Decl(narrowUnknownByTypePredicate.ts, 0, 59))
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>value3 : Symbol(value3, Decl(narrowUnknownByTypePredicate.ts, 13, 13))
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value3;
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>value3 : Symbol(value3, Decl(narrowUnknownByTypePredicate.ts, 13, 13))
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}
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declare const value4: unknown;
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>value4 : Symbol(value4, Decl(narrowUnknownByTypePredicate.ts, 18, 13))
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if (!isNullish(value4)) {
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>isNullish : Symbol(isNullish, Decl(narrowUnknownByTypePredicate.ts, 0, 59))
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>value4 : Symbol(value4, Decl(narrowUnknownByTypePredicate.ts, 18, 13))
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value4;
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>value4 : Symbol(value4, Decl(narrowUnknownByTypePredicate.ts, 18, 13))
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}
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declare class A { foo: string; }
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>A : Symbol(A, Decl(narrowUnknownByTypePredicate.ts, 21, 1))
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>foo : Symbol(A.foo, Decl(narrowUnknownByTypePredicate.ts, 23, 17))
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declare function isA(value: unknown): value is A;
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>isA : Symbol(isA, Decl(narrowUnknownByTypePredicate.ts, 23, 32))
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>value : Symbol(value, Decl(narrowUnknownByTypePredicate.ts, 24, 21))
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>value : Symbol(value, Decl(narrowUnknownByTypePredicate.ts, 24, 21))
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>A : Symbol(A, Decl(narrowUnknownByTypePredicate.ts, 21, 1))
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declare const value5: unknown;
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>value5 : Symbol(value5, Decl(narrowUnknownByTypePredicate.ts, 26, 13))
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if (isA(value5)) {
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>isA : Symbol(isA, Decl(narrowUnknownByTypePredicate.ts, 23, 32))
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>value5 : Symbol(value5, Decl(narrowUnknownByTypePredicate.ts, 26, 13))
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value5;
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>value5 : Symbol(value5, Decl(narrowUnknownByTypePredicate.ts, 26, 13))
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}
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declare const value6: unknown;
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>value6 : Symbol(value6, Decl(narrowUnknownByTypePredicate.ts, 31, 13))
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if (!isA(value6)) {
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>isA : Symbol(isA, Decl(narrowUnknownByTypePredicate.ts, 23, 32))
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>value6 : Symbol(value6, Decl(narrowUnknownByTypePredicate.ts, 31, 13))
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value6;
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>value6 : Symbol(value6, Decl(narrowUnknownByTypePredicate.ts, 31, 13))
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}
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Diff for: ‎tests/baselines/reference/narrowUnknownByTypePredicate.types

+135
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,135 @@
1+
//// [tests/cases/compiler/narrowUnknownByTypePredicate.ts] ////
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=== narrowUnknownByTypePredicate.ts ===
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declare function isNotNullish(value: unknown): value is {};
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>isNotNullish : (value: unknown) => value is {}
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> : ^ ^^ ^^^^^
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>value : unknown
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> : ^^^^^^^
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declare function isNullish(value: unknown): value is null | undefined;
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>isNullish : (value: unknown) => value is null | undefined
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> : ^ ^^ ^^^^^
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>value : unknown
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> : ^^^^^^^
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declare const value1: unknown;
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>value1 : unknown
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> : ^^^^^^^
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if (isNotNullish(value1)) {
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>isNotNullish(value1) : boolean
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> : ^^^^^^^
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>isNotNullish : (value: unknown) => value is {}
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> : ^ ^^ ^^^^^
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>value1 : unknown
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> : ^^^^^^^
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value1;
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>value1 : {}
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> : ^^
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}
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declare const value2: unknown;
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>value2 : unknown
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> : ^^^^^^^
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if (!isNotNullish(value2)) {
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>!isNotNullish(value2) : boolean
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> : ^^^^^^^
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>isNotNullish(value2) : boolean
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> : ^^^^^^^
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>isNotNullish : (value: unknown) => value is {}
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> : ^ ^^ ^^^^^
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>value2 : unknown
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> : ^^^^^^^
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value2;
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>value2 : null | undefined
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> : ^^^^^^^^^^^^^^^^
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}
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declare const value3: unknown;
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>value3 : unknown
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> : ^^^^^^^
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if (isNullish(value3)) {
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>isNullish(value3) : boolean
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> : ^^^^^^^
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>isNullish : (value: unknown) => value is null | undefined
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> : ^ ^^ ^^^^^
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>value3 : unknown
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> : ^^^^^^^
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value3;
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>value3 : null | undefined
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> : ^^^^^^^^^^^^^^^^
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}
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declare const value4: unknown;
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>value4 : unknown
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> : ^^^^^^^
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if (!isNullish(value4)) {
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>!isNullish(value4) : boolean
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> : ^^^^^^^
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>isNullish(value4) : boolean
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> : ^^^^^^^
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>isNullish : (value: unknown) => value is null | undefined
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> : ^ ^^ ^^^^^
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>value4 : unknown
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> : ^^^^^^^
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value4;
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>value4 : {}
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> : ^^
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}
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declare class A { foo: string; }
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>A : A
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> : ^
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>foo : string
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> : ^^^^^^
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declare function isA(value: unknown): value is A;
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>isA : (value: unknown) => value is A
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> : ^ ^^ ^^^^^
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>value : unknown
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> : ^^^^^^^
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declare const value5: unknown;
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>value5 : unknown
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> : ^^^^^^^
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if (isA(value5)) {
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>isA(value5) : boolean
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> : ^^^^^^^
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>isA : (value: unknown) => value is A
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> : ^ ^^ ^^^^^
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>value5 : unknown
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> : ^^^^^^^
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value5;
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>value5 : A
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> : ^
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}
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declare const value6: unknown;
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>value6 : unknown
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> : ^^^^^^^
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if (!isA(value6)) {
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>!isA(value6) : boolean
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> : ^^^^^^^
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>isA(value6) : boolean
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> : ^^^^^^^
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>isA : (value: unknown) => value is A
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> : ^ ^^ ^^^^^
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>value6 : unknown
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> : ^^^^^^^
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value6;
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>value6 : unknown
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> : ^^^^^^^
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}
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Diff for: ‎tests/cases/compiler/narrowUnknownByTypePredicate.ts

+38
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,38 @@
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// @strict: true
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// @noEmit: true
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declare function isNotNullish(value: unknown): value is {};
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declare function isNullish(value: unknown): value is null | undefined;
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declare const value1: unknown;
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if (isNotNullish(value1)) {
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value1;
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}
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declare const value2: unknown;
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if (!isNotNullish(value2)) {
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value2;
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}
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declare const value3: unknown;
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if (isNullish(value3)) {
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value3;
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}
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declare const value4: unknown;
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if (!isNullish(value4)) {
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value4;
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}
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declare class A { foo: string; }
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declare function isA(value: unknown): value is A;
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declare const value5: unknown;
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if (isA(value5)) {
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value5;
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}
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declare const value6: unknown;
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if (!isA(value6)) {
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value6;
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}

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