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Avoid generating implementation signatures in ambient contexts. #19708

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Avoid generating implementation signatures in ambient contexts. #19708

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c529526
Added tests.
DanielRosenwasser Nov 3, 2017
1a522fd
Improve signature for 'format.setOption' in fourslash.
DanielRosenwasser Nov 3, 2017
3f20f00
Avoid generating implementation signatures in ambient contexts.
DanielRosenwasser Nov 3, 2017
8a211ae
Use `NodeFlags.Ambient`. Make return type explicit for `signatureToSi…
DanielRosenwasser Nov 3, 2017
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2 changes: 1 addition & 1 deletion src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -2457,7 +2457,7 @@ namespace ts {
const result = context.encounteredError ? undefined : resultingNode;
return result;
},
signatureToSignatureDeclaration: (signature: Signature, kind: SyntaxKind, enclosingDeclaration?: Node, flags?: NodeBuilderFlags) => {
signatureToSignatureDeclaration: (signature: Signature, kind: SyntaxKind, enclosingDeclaration?: Node, flags?: NodeBuilderFlags): SignatureDeclaration | undefined => {
Debug.assert(enclosingDeclaration === undefined || (enclosingDeclaration.flags & NodeFlags.Synthesized) === 0);
const context = createNodeBuilderContext(enclosingDeclaration, flags);
const resultingNode = signatureToSignatureDeclarationHelper(signature, kind, context);
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2 changes: 1 addition & 1 deletion src/compiler/types.ts
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Expand Up @@ -2657,7 +2657,7 @@ namespace ts {
/** Note that the resulting nodes cannot be checked. */
typeToTypeNode(type: Type, enclosingDeclaration?: Node, flags?: NodeBuilderFlags): TypeNode;
/** Note that the resulting nodes cannot be checked. */
signatureToSignatureDeclaration(signature: Signature, kind: SyntaxKind, enclosingDeclaration?: Node, flags?: NodeBuilderFlags): SignatureDeclaration;
signatureToSignatureDeclaration(signature: Signature, kind: SyntaxKind, enclosingDeclaration?: Node, flags?: NodeBuilderFlags): SignatureDeclaration | undefined;
/** Note that the resulting nodes cannot be checked. */
indexInfoToIndexSignatureDeclaration(indexInfo: IndexInfo, kind: IndexKind, enclosingDeclaration?: Node, flags?: NodeBuilderFlags): IndexSignatureDeclaration;

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29 changes: 8 additions & 21 deletions src/services/codefixes/helpers.ts
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Expand Up @@ -93,14 +93,16 @@ namespace ts.codefix {
// (eg: an abstract method or interface declaration), there is a 1-1
// correspondence of declarations and signatures.
const signatures = checker.getSignaturesOfType(type, SignatureKind.Call);
const needsImplementation = !(enclosingDeclaration.flags & NodeFlags.Ambient);
if (!some(signatures)) {
return undefined;
}

if (declarations.length === 1) {
Debug.assert(signatures.length === 1);
const signature = signatures[0];
return signatureToMethodDeclaration(signature, enclosingDeclaration, createStubbedMethodBody());
const body = needsImplementation ? createStubbedMethodBody() : undefined;
return signatureToMethodDeclaration(signature, enclosingDeclaration, body);
}

const signatureDeclarations: MethodDeclaration[] = [];
Expand All @@ -119,7 +121,7 @@ namespace ts.codefix {
signatureDeclarations.push(methodDeclaration);
}
}
else {
else if (needsImplementation) {
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Is it possible that declarations.length > signatures.length but we don't want to add an implementation?
While I'm here, TypeChecker.signatureToSignatureDeclaration has a non-nullable result. Then in signatureToMethodDeclaration it's cast to another non-nullable type. Then it's tested for existence!

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Is it possible that declarations.length > signatures.length but we don't want to add an implementation?

Good catch, but I don't even understand what that check is for and what it's doing. @aozgaa?

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See this comment (a few lines above): https://github.com/Microsoft/TypeScript/pull/19708/files#diff-6d6034083b71c2ed75493db0fe725ec5R88.

An example (haven't checked by actual debugging) might be

class C {
     foo(x: number): void;
     foo(x: string): void;
     foo(x: number | string) { console.log(x); }
}

declare class D implements C {
}

Then I think adding foo to D would be an example.

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@aozgaa aozgaa Nov 17, 2017 •
edited
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I think this check should be inside createMethodImplementingSignatures, which will just omit the body if we are in an ambient context.

EDIT: no, we do not need an implementation signature in this case. Doh.

Debug.assert(declarations.length === signatures.length);
const methodImplementingSignatures = createMethodImplementingSignatures(signatures, name, optional, modifiers);
signatureDeclarations.push(methodImplementingSignatures);
Expand Down Expand Up @@ -222,32 +224,17 @@ namespace ts.codefix {
parameters.push(restParameter);
}

return createStubbedMethod(
modifiers,
name,
optional,
/*typeParameters*/ undefined,
parameters,
/*returnType*/ undefined);
}

export function createStubbedMethod(
modifiers: ReadonlyArray<Modifier>,
name: PropertyName,
optional: boolean,
typeParameters: ReadonlyArray<TypeParameterDeclaration> | undefined,
parameters: ReadonlyArray<ParameterDeclaration>,
returnType: TypeNode | undefined) {
return createMethod(
/*decorators*/ undefined,
modifiers,
/*asteriskToken*/ undefined,
name,
optional ? createToken(SyntaxKind.QuestionToken) : undefined,
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@ghost ghost Nov 3, 2017 •
edited by ghost
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It's wierd to create an optional method with a body even if that's legal.
If the method is optional, though, we don't want to make it look like it must be implemented; maybe just add an // optional, delete if you don't want to implement this comment and let the user decide?

typeParameters,
/*typeParameters*/ undefined,
parameters,
returnType,
createStubbedMethodBody());
/*returnType*/ undefined,
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We might as well give them the return type from the signature, right?

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@DanielRosenwasser DanielRosenwasser Nov 3, 2017 •
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Technically it's unsound to union the return types in most cases, but we could do that in a different PR.

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Intersection instead? It's better that they get an error when trying to return a value from the method, than that they get an error that the class failed to implement the interface, which are always hard to read..

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The intersection will be impossible to fulfill most of the time.

function foo(x: number): number;
function foo(x: string): string;
function foo(x: string | number): ??? {
  // An intersection is impossible to return
}

All I'm saying is that it's unsound to do the union, but we do allow it because it's just convenient. You're right that we should probably still do it. Just felt weird.

createStubbedMethodBody(),
);
}

function createStubbedMethodBody() {
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11 changes: 11 additions & 0 deletions tests/cases/fourslash/codeFixAmbientClassImplementInterface01.ts
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@@ -0,0 +1,11 @@
/// <reference path="fourslash.ts" />

////interface Hook {
//// tap(): void
////}
////
////declare class SyncHook implements Hook {[| |]}

verify.rangeAfterCodeFix(`
tap(): void;
`);
13 changes: 13 additions & 0 deletions tests/cases/fourslash/codeFixAmbientClassImplementInterface02.ts
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@@ -0,0 +1,13 @@
/// <reference path="fourslash.ts" />

////interface Hook {
//// tap(): void;
//// tap(x: number): string;
////}
////
////declare class SyncHook implements Hook {[| |]

verify.rangeAfterCodeFix(`
tap(): void;
tap(x: number): string;
`);
3 changes: 1 addition & 2 deletions tests/cases/fourslash/fourslash.ts
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Expand Up @@ -97,7 +97,6 @@ declare namespace FourSlashInterface {
InsertSpaceAfterTypeAssertion: boolean;
PlaceOpenBraceOnNewLineForFunctions: boolean;
PlaceOpenBraceOnNewLineForControlBlocks: boolean;
[s: string]: boolean | number | string | undefined;
}
interface Range {
fileName: string;
Expand Down Expand Up @@ -375,7 +374,7 @@ declare namespace FourSlashInterface {
setFormatOptions(options: FormatCodeOptions): any;
selection(startMarker: string, endMarker: string): void;
onType(posMarker: string, key: string): void;
setOption(name: keyof FormatCodeOptions, value: number | string | boolean): void;
setOption<K extends keyof FormatCodeOptions>(name: K, value: FormatCodeOptions[K]): void;
}
class cancellation {
resetCancelled(): void;
Expand Down