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sandersnsandersn
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Allow case comparison to undefined and null in strict null checking mode
1 parent 53a5b42 commit 843aa6c

8 files changed

Lines changed: 98 additions & 1 deletion

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‎src/compiler/checker.ts‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -15106,7 +15106,7 @@ namespace ts {
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// In a 'switch' statement, each 'case' expression must be of a type that is comparable
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// to or from the type of the 'switch' expression.
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const caseType = checkExpression(caseClause.expression);
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if (!isTypeComparableTo(expressionType, caseType)) {
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if (!isTypeEqualityComparableTo(expressionType, caseType)) {
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// expressionType is not comparable to caseType, try the reversed check and report errors if it fails
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checkTypeComparableTo(caseType, expressionType, caseClause.expression, /*headMessage*/ undefined);
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}

‎tests/baselines/reference/contextuallyTypedObjectLiteralReturnType.errors.txt‎

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@@ -0,0 +1,18 @@
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tests/cases/conformance/types/contextualTypes/methodDeclarations/contextuallyTypedObjectLiteralReturnType.ts(6,24): error TS7024: Function implicitly has return type 'any' because it does not have a return type annotation and is referenced directly or indirectly in one of its return expressions.
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tests/cases/conformance/types/contextualTypes/methodDeclarations/contextuallyTypedObjectLiteralReturnType.ts(7,38): error TS2339: Property 'length' does not exist on type 'number'.
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==== tests/cases/conformance/types/contextualTypes/methodDeclarations/contextuallyTypedObjectLiteralReturnType.ts (2 errors) ====
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function id<T>(x: T): T { return x };
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// Correct: type of fnWrapper is (y: number) => { y: number }
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var fn = function(y: number) { return { y } };
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var fnWrapper = id(fn);
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// Incorrect: type of inlineWrapper is (z: number) => any
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var inlineWrapper = id(function(z: number) { return { z } });
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~~~~~~~~
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!!! error TS7024: Function implicitly has return type 'any' because it does not have a return type annotation and is referenced directly or indirectly in one of its return expressions.
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let error1: number = fnWrapper(12).y.length; // should error
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~~~~~~
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!!! error TS2339: Property 'length' does not exist on type 'number'.
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let error2: number = inlineWrapper(12).z.length; // should error
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‎tests/baselines/reference/contextuallyTypedObjectLiteralReturnType.js‎

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@@ -0,0 +1,21 @@
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//// [contextuallyTypedObjectLiteralReturnType.ts]
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function id<T>(x: T): T { return x };
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// Correct: type of fnWrapper is (y: number) => { y: number }
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var fn = function(y: number) { return { y } };
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var fnWrapper = id(fn);
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// Incorrect: type of inlineWrapper is (z: number) => any
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var inlineWrapper = id(function(z: number) { return { z } });
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let error1: number = fnWrapper(12).y.length; // should error
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let error2: number = inlineWrapper(12).z.length; // should error
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//// [contextuallyTypedObjectLiteralReturnType.js]
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function id(x) { return x; }
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;
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// Correct: type of fnWrapper is (y: number) => { y: number }
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var fn = function (y) { return { y: y }; };
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var fnWrapper = id(fn);
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// Incorrect: type of inlineWrapper is (z: number) => any
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var inlineWrapper = id(function (z) { return { z: z }; });
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var error1 = fnWrapper(12).y.length; // should error
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var error2 = inlineWrapper(12).z.length; // should error

‎tests/baselines/reference/equalityStrictNulls.errors.txt‎

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Original file line numberDiff line numberDiff line change
@@ -81,4 +81,14 @@ tests/cases/conformance/types/typeRelationships/comparable/equalityStrictNulls.t
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!!! error TS2365: Operator '<=' cannot be applied to types 'number' and 'undefined'.
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}
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}
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function f5(x: string) {
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switch(x) {
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case null:
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break;
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case undefined:
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break;
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default:
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return;
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}
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}
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‎tests/baselines/reference/equalityStrictNulls.js‎

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Original file line numberDiff line numberDiff line change
@@ -67,6 +67,16 @@ function f4(x: number) {
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if (x <= undefined) {
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}
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}
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function f5(x: string) {
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switch(x) {
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case null:
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break;
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case undefined:
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break;
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default:
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return;
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}
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}
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//// [equalityStrictNulls.js]
@@ -134,3 +144,13 @@ function f4(x) {
134144
if (x <= undefined) {
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}
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}
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function f5(x) {
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switch (x) {
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case null:
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break;
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case undefined:
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break;
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default:
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return;
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}
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}

‎tests/cases/compiler/inferFromConstraints.ts‎

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@@ -0,0 +1,9 @@
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interface Ctor<T> {
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new(): T;
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}
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// declare function create1<T>(ctor: Ctor<T>): T;
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declare function create2<T, C extends Ctor<T>>(ctor: C): T;
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class A { a: number }
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// let a1 = create1(A).a; // a: A --> OK
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let a2 = create2(A).a; // a: {} --> Should be A

‎tests/cases/conformance/types/contextualTypes/methodDeclarations/contextuallyTypedObjectLiteralReturnType.ts‎

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@@ -0,0 +1,9 @@
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// @noImplicitAny: true
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function id<T>(x: T): T { return x };
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// Correct: type of fnWrapper is (y: number) => { y: number }
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var fn = function(y: number) { return { y } };
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var fnWrapper = id(fn);
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// Incorrect: type of inlineWrapper is (z: number) => any
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var inlineWrapper = id(function(z: number) { return { z } });
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let error1: number = fnWrapper(12).y.length; // should error
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let error2: number = inlineWrapper(12).z.length; // should error

‎tests/cases/conformance/types/typeRelationships/comparable/equalityStrictNulls.ts‎

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Original file line numberDiff line numberDiff line change
@@ -67,3 +67,13 @@ function f4(x: number) {
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if (x <= undefined) {
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}
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}
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function f5(x: string) {
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switch(x) {
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case null:
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break;
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case undefined:
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break;
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default:
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return;
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}
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}

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