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ahejlsbergahejlsberg
authoredSep 1, 2022
{} & null and {} & undefined should always be never (#50553)
* {} & null and {} & undefined should be never in non-strictNullChecks mode * Add tests * Address code review feedback * Accept new baselines
·
v5.8.2v4.9-beta
1 parent 238c341 commit 6db2c88

11 files changed

+347
-1
lines changed
 

‎src/compiler/checker.ts

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@@ -15166,7 +15166,7 @@ namespace ts {
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return includes & TypeFlags.IncludesWildcard ? wildcardType : anyType;
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}
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if (!strictNullChecks && includes & TypeFlags.Nullable) {
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return includes & TypeFlags.Undefined ? undefinedType : nullType;
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return includes & TypeFlags.IncludesEmptyObject ? neverType : includes & TypeFlags.Undefined ? undefinedType : nullType;
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}
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if (includes & TypeFlags.String && includes & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) ||
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includes & TypeFlags.Number && includes & TypeFlags.NumberLiteral ||

‎tests/baselines/reference/NonNullableInNonStrictMode.js

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//// [NonNullableInNonStrictMode.ts]
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// These should all resolve to never
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type T0 = NonNullable<null>;
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type T1 = NonNullable<undefined>;
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type T2 = null & {};
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type T3 = undefined & {};
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type T4 = null & undefined;
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type T6 = null & { a: string } & {};
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// Repro from #50519
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type NonNullableNew<T> = T & {};
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type NonNullableOld<T> = T extends null | undefined ? never : T;
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type IsNullWithoutStrictNullChecks = NonNullableNew<null>;
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type IsAlwaysNever = NonNullableOld<null>;
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//// [NonNullableInNonStrictMode.js]
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// These should all resolve to never

‎tests/baselines/reference/NonNullableInNonStrictMode.symbols

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@@ -0,0 +1,45 @@
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=== tests/cases/compiler/NonNullableInNonStrictMode.ts ===
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// These should all resolve to never
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type T0 = NonNullable<null>;
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>T0 : Symbol(T0, Decl(NonNullableInNonStrictMode.ts, 0, 0))
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>NonNullable : Symbol(NonNullable, Decl(lib.es5.d.ts, --, --))
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type T1 = NonNullable<undefined>;
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>T1 : Symbol(T1, Decl(NonNullableInNonStrictMode.ts, 2, 28))
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>NonNullable : Symbol(NonNullable, Decl(lib.es5.d.ts, --, --))
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type T2 = null & {};
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>T2 : Symbol(T2, Decl(NonNullableInNonStrictMode.ts, 3, 33))
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type T3 = undefined & {};
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>T3 : Symbol(T3, Decl(NonNullableInNonStrictMode.ts, 4, 20))
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type T4 = null & undefined;
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>T4 : Symbol(T4, Decl(NonNullableInNonStrictMode.ts, 5, 25))
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type T6 = null & { a: string } & {};
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>T6 : Symbol(T6, Decl(NonNullableInNonStrictMode.ts, 6, 27))
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>a : Symbol(a, Decl(NonNullableInNonStrictMode.ts, 7, 18))
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// Repro from #50519
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type NonNullableNew<T> = T & {};
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>NonNullableNew : Symbol(NonNullableNew, Decl(NonNullableInNonStrictMode.ts, 7, 36))
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>T : Symbol(T, Decl(NonNullableInNonStrictMode.ts, 11, 20))
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>T : Symbol(T, Decl(NonNullableInNonStrictMode.ts, 11, 20))
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type NonNullableOld<T> = T extends null | undefined ? never : T;
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>NonNullableOld : Symbol(NonNullableOld, Decl(NonNullableInNonStrictMode.ts, 11, 32))
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>T : Symbol(T, Decl(NonNullableInNonStrictMode.ts, 12, 20))
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>T : Symbol(T, Decl(NonNullableInNonStrictMode.ts, 12, 20))
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>T : Symbol(T, Decl(NonNullableInNonStrictMode.ts, 12, 20))
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type IsNullWithoutStrictNullChecks = NonNullableNew<null>;
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>IsNullWithoutStrictNullChecks : Symbol(IsNullWithoutStrictNullChecks, Decl(NonNullableInNonStrictMode.ts, 12, 64))
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>NonNullableNew : Symbol(NonNullableNew, Decl(NonNullableInNonStrictMode.ts, 7, 36))
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type IsAlwaysNever = NonNullableOld<null>;
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>IsAlwaysNever : Symbol(IsAlwaysNever, Decl(NonNullableInNonStrictMode.ts, 14, 58))
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>NonNullableOld : Symbol(NonNullableOld, Decl(NonNullableInNonStrictMode.ts, 11, 32))
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‎tests/baselines/reference/NonNullableInNonStrictMode.types

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=== tests/cases/compiler/NonNullableInNonStrictMode.ts ===
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// These should all resolve to never
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type T0 = NonNullable<null>;
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>T0 : never
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>null : null
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type T1 = NonNullable<undefined>;
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>T1 : never
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type T2 = null & {};
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>T2 : never
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>null : null
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type T3 = undefined & {};
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>T3 : never
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type T4 = null & undefined;
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>T4 : never
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>null : null
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type T6 = null & { a: string } & {};
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>T6 : never
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>null : null
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>a : string
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// Repro from #50519
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type NonNullableNew<T> = T & {};
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>NonNullableNew : NonNullableNew<T>
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type NonNullableOld<T> = T extends null | undefined ? never : T;
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>NonNullableOld : NonNullableOld<T>
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>null : null
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type IsNullWithoutStrictNullChecks = NonNullableNew<null>;
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>IsNullWithoutStrictNullChecks : never
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>null : null
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type IsAlwaysNever = NonNullableOld<null>;
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>IsAlwaysNever : never
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>null : null
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‎tests/baselines/reference/nonNullableAndObjectIntersections(strict=false).js

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//// [nonNullableAndObjectIntersections.ts]
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// These should all resolve to never
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type T0 = NonNullable<null>;
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type T1 = NonNullable<undefined>;
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type T2 = null & {};
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type T3 = undefined & {};
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type T4 = null & undefined;
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type T6 = null & { a: string } & {};
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// Repro from #50519
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type NonNullableNew<T> = T & {};
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type NonNullableOld<T> = T extends null | undefined ? never : T;
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type TestNew = NonNullableNew<null>;
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type TestOld = NonNullableOld<null>;
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//// [nonNullableAndObjectIntersections.js]
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// These should all resolve to never

‎tests/baselines/reference/nonNullableAndObjectIntersections(strict=false).symbols

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=== tests/cases/compiler/nonNullableAndObjectIntersections.ts ===
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// These should all resolve to never
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type T0 = NonNullable<null>;
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>T0 : Symbol(T0, Decl(nonNullableAndObjectIntersections.ts, 0, 0))
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>NonNullable : Symbol(NonNullable, Decl(lib.es5.d.ts, --, --))
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type T1 = NonNullable<undefined>;
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>T1 : Symbol(T1, Decl(nonNullableAndObjectIntersections.ts, 2, 28))
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>NonNullable : Symbol(NonNullable, Decl(lib.es5.d.ts, --, --))
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type T2 = null & {};
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>T2 : Symbol(T2, Decl(nonNullableAndObjectIntersections.ts, 3, 33))
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type T3 = undefined & {};
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>T3 : Symbol(T3, Decl(nonNullableAndObjectIntersections.ts, 4, 20))
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type T4 = null & undefined;
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>T4 : Symbol(T4, Decl(nonNullableAndObjectIntersections.ts, 5, 25))
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type T6 = null & { a: string } & {};
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>T6 : Symbol(T6, Decl(nonNullableAndObjectIntersections.ts, 6, 27))
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>a : Symbol(a, Decl(nonNullableAndObjectIntersections.ts, 7, 18))
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// Repro from #50519
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type NonNullableNew<T> = T & {};
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>NonNullableNew : Symbol(NonNullableNew, Decl(nonNullableAndObjectIntersections.ts, 7, 36))
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>T : Symbol(T, Decl(nonNullableAndObjectIntersections.ts, 11, 20))
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>T : Symbol(T, Decl(nonNullableAndObjectIntersections.ts, 11, 20))
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type NonNullableOld<T> = T extends null | undefined ? never : T;
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>NonNullableOld : Symbol(NonNullableOld, Decl(nonNullableAndObjectIntersections.ts, 11, 32))
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>T : Symbol(T, Decl(nonNullableAndObjectIntersections.ts, 12, 20))
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>T : Symbol(T, Decl(nonNullableAndObjectIntersections.ts, 12, 20))
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>T : Symbol(T, Decl(nonNullableAndObjectIntersections.ts, 12, 20))
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type TestNew = NonNullableNew<null>;
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>TestNew : Symbol(TestNew, Decl(nonNullableAndObjectIntersections.ts, 12, 64))
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>NonNullableNew : Symbol(NonNullableNew, Decl(nonNullableAndObjectIntersections.ts, 7, 36))
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type TestOld = NonNullableOld<null>;
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>TestOld : Symbol(TestOld, Decl(nonNullableAndObjectIntersections.ts, 14, 36))
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>NonNullableOld : Symbol(NonNullableOld, Decl(nonNullableAndObjectIntersections.ts, 11, 32))
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‎tests/baselines/reference/nonNullableAndObjectIntersections(strict=false).types

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=== tests/cases/compiler/nonNullableAndObjectIntersections.ts ===
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// These should all resolve to never
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type T0 = NonNullable<null>;
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>T0 : never
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>null : null
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type T1 = NonNullable<undefined>;
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>T1 : never
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type T2 = null & {};
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>T2 : never
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>null : null
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type T3 = undefined & {};
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>T3 : never
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type T4 = null & undefined;
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>T4 : never
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>null : null
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type T6 = null & { a: string } & {};
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>T6 : never
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>null : null
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>a : string
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// Repro from #50519
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type NonNullableNew<T> = T & {};
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>NonNullableNew : NonNullableNew<T>
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type NonNullableOld<T> = T extends null | undefined ? never : T;
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>NonNullableOld : NonNullableOld<T>
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>null : null
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type TestNew = NonNullableNew<null>;
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>TestNew : never
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>null : null
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type TestOld = NonNullableOld<null>;
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>TestOld : never
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>null : null
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‎tests/baselines/reference/nonNullableAndObjectIntersections(strict=true).js

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//// [nonNullableAndObjectIntersections.ts]
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// These should all resolve to never
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type T0 = NonNullable<null>;
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type T1 = NonNullable<undefined>;
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type T2 = null & {};
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type T3 = undefined & {};
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type T4 = null & undefined;
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type T6 = null & { a: string } & {};
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// Repro from #50519
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type NonNullableNew<T> = T & {};
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type NonNullableOld<T> = T extends null | undefined ? never : T;
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type TestNew = NonNullableNew<null>;
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type TestOld = NonNullableOld<null>;
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//// [nonNullableAndObjectIntersections.js]
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"use strict";
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// These should all resolve to never

‎tests/baselines/reference/nonNullableAndObjectIntersections(strict=true).symbols

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=== tests/cases/compiler/nonNullableAndObjectIntersections.ts ===
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// These should all resolve to never
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type T0 = NonNullable<null>;
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>T0 : Symbol(T0, Decl(nonNullableAndObjectIntersections.ts, 0, 0))
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>NonNullable : Symbol(NonNullable, Decl(lib.es5.d.ts, --, --))
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type T1 = NonNullable<undefined>;
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>T1 : Symbol(T1, Decl(nonNullableAndObjectIntersections.ts, 2, 28))
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>NonNullable : Symbol(NonNullable, Decl(lib.es5.d.ts, --, --))
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type T2 = null & {};
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>T2 : Symbol(T2, Decl(nonNullableAndObjectIntersections.ts, 3, 33))
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type T3 = undefined & {};
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>T3 : Symbol(T3, Decl(nonNullableAndObjectIntersections.ts, 4, 20))
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type T4 = null & undefined;
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>T4 : Symbol(T4, Decl(nonNullableAndObjectIntersections.ts, 5, 25))
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type T6 = null & { a: string } & {};
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>T6 : Symbol(T6, Decl(nonNullableAndObjectIntersections.ts, 6, 27))
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>a : Symbol(a, Decl(nonNullableAndObjectIntersections.ts, 7, 18))
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// Repro from #50519
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type NonNullableNew<T> = T & {};
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>NonNullableNew : Symbol(NonNullableNew, Decl(nonNullableAndObjectIntersections.ts, 7, 36))
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>T : Symbol(T, Decl(nonNullableAndObjectIntersections.ts, 11, 20))
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>T : Symbol(T, Decl(nonNullableAndObjectIntersections.ts, 11, 20))
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type NonNullableOld<T> = T extends null | undefined ? never : T;
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>NonNullableOld : Symbol(NonNullableOld, Decl(nonNullableAndObjectIntersections.ts, 11, 32))
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>T : Symbol(T, Decl(nonNullableAndObjectIntersections.ts, 12, 20))
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>T : Symbol(T, Decl(nonNullableAndObjectIntersections.ts, 12, 20))
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>T : Symbol(T, Decl(nonNullableAndObjectIntersections.ts, 12, 20))
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type TestNew = NonNullableNew<null>;
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>TestNew : Symbol(TestNew, Decl(nonNullableAndObjectIntersections.ts, 12, 64))
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>NonNullableNew : Symbol(NonNullableNew, Decl(nonNullableAndObjectIntersections.ts, 7, 36))
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type TestOld = NonNullableOld<null>;
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>TestOld : Symbol(TestOld, Decl(nonNullableAndObjectIntersections.ts, 14, 36))
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>NonNullableOld : Symbol(NonNullableOld, Decl(nonNullableAndObjectIntersections.ts, 11, 32))
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‎tests/baselines/reference/nonNullableAndObjectIntersections(strict=true).types

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=== tests/cases/compiler/nonNullableAndObjectIntersections.ts ===
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// These should all resolve to never
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type T0 = NonNullable<null>;
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>T0 : never
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>null : null
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type T1 = NonNullable<undefined>;
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>T1 : never
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type T2 = null & {};
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>T2 : never
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>null : null
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type T3 = undefined & {};
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>T3 : never
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type T4 = null & undefined;
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>T4 : never
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>null : null
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type T6 = null & { a: string } & {};
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>T6 : never
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>null : null
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>a : string
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// Repro from #50519
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type NonNullableNew<T> = T & {};
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>NonNullableNew : NonNullableNew<T>
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type NonNullableOld<T> = T extends null | undefined ? never : T;
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>NonNullableOld : NonNullableOld<T>
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>null : null
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type TestNew = NonNullableNew<null>;
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>TestNew : never
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>null : null
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type TestOld = NonNullableOld<null>;
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>TestOld : never
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>null : null
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‎tests/cases/compiler/nonNullableAndObjectIntersections.ts

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// @strict: true, false
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// These should all resolve to never
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type T0 = NonNullable<null>;
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type T1 = NonNullable<undefined>;
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type T2 = null & {};
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type T3 = undefined & {};
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type T4 = null & undefined;
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type T6 = null & { a: string } & {};
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// Repro from #50519
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type NonNullableNew<T> = T & {};
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type NonNullableOld<T> = T extends null | undefined ? never : T;
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type TestNew = NonNullableNew<null>;
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type TestOld = NonNullableOld<null>;

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