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Covariant checking for callback parameters #15104

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Merged
merged 9 commits into from
Apr 18, 2017
Merged

Covariant checking for callback parameters #15104

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8ae3e05
Treat callback parameters as strictly covariant
ahejlsberg Apr 8, 2017
eebd67f
Fix callback types to match covariantly
ahejlsberg Apr 8, 2017
11543d7
Accept new baselines
ahejlsberg Apr 8, 2017
50f84b1
Add tests
ahejlsberg Apr 8, 2017
189fc51
Check callback return values bi-variantly
ahejlsberg Apr 10, 2017
33bc9d1
Accept new baselines
ahejlsberg Apr 10, 2017
510bc81
Add another test case
ahejlsberg Apr 10, 2017
ec35b80
Allow callbacks unioned with null and/or undefined
ahejlsberg Apr 11, 2017
3cda0ea
Update tests
ahejlsberg Apr 11, 2017
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32 changes: 26 additions & 6 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -8157,7 +8157,8 @@ namespace ts {
function isSignatureAssignableTo(source: Signature,
target: Signature,
ignoreReturnTypes: boolean): boolean {
return compareSignaturesRelated(source, target, ignoreReturnTypes, /*reportErrors*/ false, /*errorReporter*/ undefined, compareTypesAssignable) !== Ternary.False;
return compareSignaturesRelated(source, target, /*checkAsCallback*/ false, ignoreReturnTypes, /*reportErrors*/ false,
/*errorReporter*/ undefined, compareTypesAssignable) !== Ternary.False;
}

type ErrorReporter = (message: DiagnosticMessage, arg0?: string, arg1?: string) => void;
Expand All @@ -8167,6 +8168,7 @@ namespace ts {
*/
function compareSignaturesRelated(source: Signature,
target: Signature,
checkAsCallback: boolean,
ignoreReturnTypes: boolean,
reportErrors: boolean,
errorReporter: ErrorReporter,
Expand Down Expand Up @@ -8209,9 +8211,23 @@ namespace ts {
const sourceParams = source.parameters;
const targetParams = target.parameters;
for (let i = 0; i < checkCount; i++) {
const s = i < sourceMax ? getTypeOfParameter(sourceParams[i]) : getRestTypeOfSignature(source);
const t = i < targetMax ? getTypeOfParameter(targetParams[i]) : getRestTypeOfSignature(target);
const related = compareTypes(s, t, /*reportErrors*/ false) || compareTypes(t, s, reportErrors);
const sourceType = i < sourceMax ? getTypeOfParameter(sourceParams[i]) : getRestTypeOfSignature(source);
const targetType = i < targetMax ? getTypeOfParameter(targetParams[i]) : getRestTypeOfSignature(target);
const sourceSig = getSingleCallSignature(getNonNullableType(sourceType));
const targetSig = getSingleCallSignature(getNonNullableType(targetType));
// In order to ensure that any generic type Foo<T> is at least co-variant with respect to T no matter
// how Foo uses T, we need to relate parameters bi-variantly (given that parameters are input positions,
// they naturally relate only contra-variantly). However, if the source and target parameters both have
// function types with a single call signature, we known we are relating two callback parameters. In
// that case it is sufficient to only relate the parameters of the signatures co-variantly because,
// similar to return values, callback parameters are output positions. This means that a Promise<T>,
// where T is used only in callback parameter positions, will be co-variant (as opposed to bi-variant)
// with respect to T.
const callbacks = sourceSig && targetSig && !sourceSig.typePredicate && !targetSig.typePredicate &&
(getFalsyFlags(sourceType) & TypeFlags.Nullable) === (getFalsyFlags(targetType) & TypeFlags.Nullable);
const related = callbacks ?
compareSignaturesRelated(targetSig, sourceSig, /*checkAsCallback*/ true, /*ignoreReturnTypes*/ false, reportErrors, errorReporter, compareTypes) :
!checkAsCallback && compareTypes(sourceType, targetType, /*reportErrors*/ false) || compareTypes(targetType, sourceType, reportErrors);
if (!related) {
if (reportErrors) {
errorReporter(Diagnostics.Types_of_parameters_0_and_1_are_incompatible,
Expand Down Expand Up @@ -8243,7 +8259,11 @@ namespace ts {
}
}
else {
result &= compareTypes(sourceReturnType, targetReturnType, reportErrors);
// When relating callback signatures, we still need to relate return types bi-variantly as otherwise
// the containing type wouldn't be co-variant. For example, interface Foo<T> { add(cb: () => T): void }
// wouldn't be co-variant for T without this rule.
result &= checkAsCallback && compareTypes(targetReturnType, sourceReturnType, /*reportErrors*/ false) ||
compareTypes(sourceReturnType, targetReturnType, reportErrors);
}

}
Expand Down Expand Up @@ -9210,7 +9230,7 @@ namespace ts {
* See signatureAssignableTo, compareSignaturesIdentical
*/
function signatureRelatedTo(source: Signature, target: Signature, reportErrors: boolean): Ternary {
return compareSignaturesRelated(source, target, /*ignoreReturnTypes*/ false, reportErrors, reportError, isRelatedTo);
return compareSignaturesRelated(source, target, /*checkAsCallback*/ false, /*ignoreReturnTypes*/ false, reportErrors, reportError, isRelatedTo);
}

function signaturesIdenticalTo(source: Type, target: Type, kind: SignatureKind): Ternary {
Expand Down
2 changes: 1 addition & 1 deletion src/compiler/parser.ts
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Expand Up @@ -57,7 +57,7 @@ namespace ts {
// The visitXXX functions could be written as local functions that close over the cbNode and cbNodeArray
// callback parameters, but that causes a closure allocation for each invocation with noticeable effects
// on performance.
const visitNodes: (cb: (node: Node | Node[]) => T, nodes: Node[]) => T = cbNodeArray ? visitNodeArray : visitEachNode;
const visitNodes: (cb: ((node: Node) => T) | ((node: Node[]) => T), nodes: Node[]) => T = cbNodeArray ? visitNodeArray : visitEachNode;
const cbNodes = cbNodeArray || cbNode;
switch (node.kind) {
case SyntaxKind.QualifiedName:
Expand Down
2 changes: 1 addition & 1 deletion src/compiler/visitor.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -885,7 +885,7 @@ namespace ts {
return initial;
}

const reduceNodes: (nodes: NodeArray<Node>, f: (memo: T, node: Node | NodeArray<Node>) => T, initial: T) => T = cbNodeArray ? reduceNodeArray : reduceLeft;
const reduceNodes: (nodes: NodeArray<Node>, f: ((memo: T, node: Node) => T) | ((memo: T, node: NodeArray<Node>) => T), initial: T) => T = cbNodeArray ? reduceNodeArray : reduceLeft;
const cbNodes = cbNodeArray || cbNode;
const kind = node.kind;

Expand Down
113 changes: 113 additions & 0 deletions tests/baselines/reference/assignmentCompatWithCallSignatures3.errors.txt
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@@ -0,0 +1,113 @@
tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures3.ts(71,1): error TS2322: Type '(x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived' is not assignable to type '<T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: string; bing: number; }) => U) => (r: T) => U'.
Types of parameters 'y' and 'y' are incompatible.
Types of parameters 'arg2' and 'arg2' are incompatible.
Type 'Base' is not assignable to type '{ foo: string; bing: number; }'.
Property 'bing' is missing in type 'Base'.


==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures3.ts (1 errors) ====
// these are all permitted with the current rules, since we do not do contextual signature instantiation

class Base { foo: string; }
class Derived extends Base { bar: string; }
class Derived2 extends Derived { baz: string; }
class OtherDerived extends Base { bing: string; }

var a: (x: number) => number[];
var a2: (x: number) => string[];
var a3: (x: number) => void;
var a4: (x: string, y: number) => string;
var a5: (x: (arg: string) => number) => string;
var a6: (x: (arg: Base) => Derived) => Base;
var a7: (x: (arg: Base) => Derived) => (r: Base) => Derived;
var a8: (x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived;
var a9: (x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived;
var a10: (...x: Derived[]) => Derived;
var a11: (x: { foo: string }, y: { foo: string; bar: string }) => Base;
var a12: (x: Array<Base>, y: Array<Derived2>) => Array<Derived>;
var a13: (x: Array<Base>, y: Array<Derived>) => Array<Derived>;
var a14: (x: { a: string; b: number }) => Object;
var a15: {
(x: number): number[];
(x: string): string[];
}
var a16: {
<T extends Derived>(x: T): number[];
<U extends Base>(x: U): number[];
}
var a17: {
(x: (a: number) => number): number[];
(x: (a: string) => string): string[];
};
var a18: {
(x: {
(a: number): number;
(a: string): string;
}): any[];
(x: {
(a: boolean): boolean;
(a: Date): Date;
}): any[];
}

var b: <T>(x: T) => T[];
a = b; // ok
b = a; // ok
var b2: <T>(x: T) => string[];
a2 = b2; // ok
b2 = a2; // ok
var b3: <T>(x: T) => T;
a3 = b3; // ok
b3 = a3; // ok
var b4: <T, U>(x: T, y: U) => T;
a4 = b4; // ok
b4 = a4; // ok
var b5: <T, U>(x: (arg: T) => U) => T;
a5 = b5; // ok
b5 = a5; // ok
var b6: <T extends Base, U extends Derived>(x: (arg: T) => U) => T;
a6 = b6; // ok
b6 = a6; // ok
var b7: <T extends Base, U extends Derived>(x: (arg: T) => U) => (r: T) => U;
a7 = b7; // ok
b7 = a7; // ok
var b8: <T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: T) => U) => (r: T) => U;
a8 = b8; // ok
b8 = a8; // ok
var b9: <T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: string; bing: number }) => U) => (r: T) => U;
a9 = b9; // ok
b9 = a9; // ok
~~
!!! error TS2322: Type '(x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived' is not assignable to type '<T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: string; bing: number; }) => U) => (r: T) => U'.
!!! error TS2322: Types of parameters 'y' and 'y' are incompatible.
!!! error TS2322: Types of parameters 'arg2' and 'arg2' are incompatible.
!!! error TS2322: Type 'Base' is not assignable to type '{ foo: string; bing: number; }'.
!!! error TS2322: Property 'bing' is missing in type 'Base'.
var b10: <T extends Derived>(...x: T[]) => T;
a10 = b10; // ok
b10 = a10; // ok
var b11: <T extends Base>(x: T, y: T) => T;
a11 = b11; // ok
b11 = a11; // ok
var b12: <T extends Array<Base>>(x: Array<Base>, y: T) => Array<Derived>;
a12 = b12; // ok
b12 = a12; // ok
var b13: <T extends Array<Derived>>(x: Array<Base>, y: T) => T;
a13 = b13; // ok
b13 = a13; // ok
var b14: <T>(x: { a: T; b: T }) => T;
a14 = b14; // ok
b14 = a14; // ok
var b15: <T>(x: T) => T[];
a15 = b15; // ok
b15 = a15; // ok
var b16: <T extends Base>(x: T) => number[];
a16 = b16; // ok
b16 = a16; // ok
var b17: <T>(x: (a: T) => T) => T[]; // ok
a17 = b17; // ok
b17 = a17; // ok
var b18: <T>(x: (a: T) => T) => T[];
a18 = b18; // ok
b18 = a18; // ok

36 changes: 16 additions & 20 deletions tests/baselines/reference/assignmentCompatWithCallSignatures4.errors.txt
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Original file line number Diff line number Diff line change
@@ -1,17 +1,15 @@
tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures4.ts(52,9): error TS2322: Type '<T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U' is not assignable to type '(x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived'.
Types of parameters 'y' and 'y' are incompatible.
Type '(arg2: Base) => Derived' is not assignable to type '(arg2: { foo: number; }) => any'.
Types of parameters 'arg2' and 'arg2' are incompatible.
Type '{ foo: number; }' is not assignable to type 'Base'.
Types of property 'foo' are incompatible.
Type 'number' is not assignable to type 'string'.
Types of parameters 'arg2' and 'arg2' are incompatible.
Type '{ foo: number; }' is not assignable to type 'Base'.
Types of property 'foo' are incompatible.
Type 'number' is not assignable to type 'string'.
tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures4.ts(53,9): error TS2322: Type '(x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived' is not assignable to type '<T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U'.
Types of parameters 'y' and 'y' are incompatible.
Type '(arg2: { foo: number; }) => any' is not assignable to type '(arg2: Base) => Derived'.
Types of parameters 'arg2' and 'arg2' are incompatible.
Type 'Base' is not assignable to type '{ foo: number; }'.
Types of property 'foo' are incompatible.
Type 'string' is not assignable to type 'number'.
Types of parameters 'arg2' and 'arg2' are incompatible.
Type 'Base' is not assignable to type '{ foo: number; }'.
Types of property 'foo' are incompatible.
Type 'string' is not assignable to type 'number'.


==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures4.ts (2 errors) ====
Expand Down Expand Up @@ -70,20 +68,18 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
~~
!!! error TS2322: Type '<T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U' is not assignable to type '(x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived'.
!!! error TS2322: Types of parameters 'y' and 'y' are incompatible.
!!! error TS2322: Type '(arg2: Base) => Derived' is not assignable to type '(arg2: { foo: number; }) => any'.
!!! error TS2322: Types of parameters 'arg2' and 'arg2' are incompatible.
!!! error TS2322: Type '{ foo: number; }' is not assignable to type 'Base'.
!!! error TS2322: Types of property 'foo' are incompatible.
!!! error TS2322: Type 'number' is not assignable to type 'string'.
!!! error TS2322: Types of parameters 'arg2' and 'arg2' are incompatible.
!!! error TS2322: Type '{ foo: number; }' is not assignable to type 'Base'.
!!! error TS2322: Types of property 'foo' are incompatible.
!!! error TS2322: Type 'number' is not assignable to type 'string'.
b8 = a8; // error, { foo: number } and Base are incompatible
~~
!!! error TS2322: Type '(x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived' is not assignable to type '<T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U'.
!!! error TS2322: Types of parameters 'y' and 'y' are incompatible.
!!! error TS2322: Type '(arg2: { foo: number; }) => any' is not assignable to type '(arg2: Base) => Derived'.
!!! error TS2322: Types of parameters 'arg2' and 'arg2' are incompatible.
!!! error TS2322: Type 'Base' is not assignable to type '{ foo: number; }'.
!!! error TS2322: Types of property 'foo' are incompatible.
!!! error TS2322: Type 'string' is not assignable to type 'number'.
!!! error TS2322: Types of parameters 'arg2' and 'arg2' are incompatible.
!!! error TS2322: Type 'Base' is not assignable to type '{ foo: number; }'.
!!! error TS2322: Types of property 'foo' are incompatible.
!!! error TS2322: Type 'string' is not assignable to type 'number'.


var b10: <T extends Derived>(...x: T[]) => T;
Expand Down
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