Improve some completions on generic object literals (microsoft#34855)

* Weird fix

* Slightly better I guess

* Update APIs

* Make `hasTypeArguments` do what it says on the tin

* Fix merge mistake

Author: andrewbranch

src/compiler/checker.ts

@@ -21160,9 +21160,9 @@ namespace ts {
             if (isJsxOpeningLikeElement(callTarget) && argIndex === 0) {
                 return getEffectiveFirstArgumentForJsxSignature(signature, callTarget);
             }
-            if (contextFlags && contextFlags & ContextFlags.Completion && signature.target) {
+            if (contextFlags && contextFlags & ContextFlags.BaseConstraint && signature.target && !hasTypeArguments(callTarget)) {
                 const baseSignature = getBaseSignature(signature.target);
-                return intersectTypes(getTypeAtPosition(signature, argIndex), getTypeAtPosition(baseSignature, argIndex));
+                return getTypeAtPosition(baseSignature, argIndex);
             }
             return getTypeAtPosition(signature, argIndex);
         }

src/compiler/types.ts

@@ -709,6 +709,13 @@ namespace ts {
         | JSDocOptionalType
         | JSDocVariadicType;
 
+    export type HasTypeArguments =
+        | CallExpression
+        | NewExpression
+        | TaggedTemplateExpression
+        | JsxOpeningElement
+        | JsxSelfClosingElement;
+
     export type HasInitializer =
         | HasExpressionInitializer
         | ForStatement
@@ -3537,10 +3544,10 @@ namespace ts {
 
     /* @internal */
     export const enum ContextFlags {
-        None          = 0,
-        Signature     = 1 << 0, // Obtaining contextual signature
-        NoConstraints = 1 << 1, // Don't obtain type variable constraints
-        Completion    = 1 << 2, // Obtaining constraint type for completion
+        None           = 0,
+        Signature      = 1 << 0, // Obtaining contextual signature
+        NoConstraints  = 1 << 1, // Don't obtain type variable constraints
+        BaseConstraint = 1 << 2, // Use base constraint type for completions
     }
 
     // NOTE: If modifying this enum, must modify `TypeFormatFlags` too!

src/compiler/utilities.ts

@@ -2433,6 +2433,10 @@ namespace ts {
         return (node as ParameterDeclaration).dotDotDotToken !== undefined || !!type && type.kind === SyntaxKind.JSDocVariadicType;
     }
 
+    export function hasTypeArguments(node: Node): node is HasTypeArguments {
+        return !!(node as HasTypeArguments).typeArguments;
+    }
+
     export const enum AssignmentKind {
         None, Definite, Compound
     }

src/services/completions.ts

@@ -1279,7 +1279,7 @@ namespace ts.Completions {
             // Cursor is inside a JSX self-closing element or opening element
             const attrsType = jsxContainer && typeChecker.getContextualType(jsxContainer.attributes);
             if (!attrsType) return GlobalsSearch.Continue;
-            symbols = filterJsxAttributes(getPropertiesForObjectExpression(attrsType, jsxContainer!.attributes, typeChecker), jsxContainer!.attributes.properties);
+            symbols = filterJsxAttributes(getPropertiesForObjectExpression(attrsType, /*baseType*/ undefined, jsxContainer!.attributes, typeChecker), jsxContainer!.attributes.properties);
             setSortTextToOptionalMember();
             completionKind = CompletionKind.MemberLike;
             isNewIdentifierLocation = false;
@@ -1798,10 +1798,11 @@ namespace ts.Completions {
             let existingMembers: readonly Declaration[] | undefined;
 
             if (objectLikeContainer.kind === SyntaxKind.ObjectLiteralExpression) {
-                const typeForObject = typeChecker.getContextualType(objectLikeContainer, ContextFlags.Completion);
-                if (!typeForObject) return GlobalsSearch.Fail;
-                isNewIdentifierLocation = hasIndexSignature(typeForObject);
-                typeMembers = getPropertiesForObjectExpression(typeForObject, objectLikeContainer, typeChecker);
+                const instantiatedType = typeChecker.getContextualType(objectLikeContainer);
+                const baseType = instantiatedType && typeChecker.getContextualType(objectLikeContainer, ContextFlags.BaseConstraint);
+                if (!instantiatedType || !baseType) return GlobalsSearch.Fail;
+                isNewIdentifierLocation = hasIndexSignature(instantiatedType || baseType);
+                typeMembers = getPropertiesForObjectExpression(instantiatedType, baseType, objectLikeContainer, typeChecker);
                 existingMembers = objectLikeContainer.properties;
             }
             else {
@@ -2538,15 +2539,19 @@ namespace ts.Completions {
         return jsdoc && jsdoc.tags && (rangeContainsPosition(jsdoc, position) ? findLast(jsdoc.tags, tag => tag.pos < position) : undefined);
     }
 
-    function getPropertiesForObjectExpression(contextualType: Type, obj: ObjectLiteralExpression | JsxAttributes, checker: TypeChecker): Symbol[] {
-        return contextualType.isUnion()
-            ? checker.getAllPossiblePropertiesOfTypes(contextualType.types.filter(memberType =>
+    function getPropertiesForObjectExpression(contextualType: Type, baseConstrainedType: Type | undefined, obj: ObjectLiteralExpression | JsxAttributes, checker: TypeChecker): Symbol[] {
+        const type = baseConstrainedType && !(baseConstrainedType.flags & TypeFlags.AnyOrUnknown)
+            ? checker.getUnionType([contextualType, baseConstrainedType])
+            : contextualType;
+
+        return type.isUnion()
+            ? checker.getAllPossiblePropertiesOfTypes(type.types.filter(memberType =>
                 // If we're providing completions for an object literal, skip primitive, array-like, or callable types since those shouldn't be implemented by object literals.
                 !(memberType.flags & TypeFlags.Primitive ||
                     checker.isArrayLikeType(memberType) ||
                     typeHasCallOrConstructSignatures(memberType, checker) ||
                     checker.isTypeInvalidDueToUnionDiscriminant(memberType, obj))))
-            : contextualType.getApparentProperties();
+            : type.getApparentProperties();
     }
 
     /**

tests/baselines/reference/api/tsserverlibrary.d.ts

@@ -502,6 +502,7 @@ declare namespace ts {
     }
     export type HasJSDoc = ParameterDeclaration | CallSignatureDeclaration | ConstructSignatureDeclaration | MethodSignature | PropertySignature | ArrowFunction | ParenthesizedExpression | SpreadAssignment | ShorthandPropertyAssignment | PropertyAssignment | FunctionExpression | LabeledStatement | ExpressionStatement | VariableStatement | FunctionDeclaration | ConstructorDeclaration | MethodDeclaration | PropertyDeclaration | AccessorDeclaration | ClassLikeDeclaration | InterfaceDeclaration | TypeAliasDeclaration | EnumMember | EnumDeclaration | ModuleDeclaration | ImportEqualsDeclaration | IndexSignatureDeclaration | FunctionTypeNode | ConstructorTypeNode | JSDocFunctionType | ExportDeclaration | EndOfFileToken;
     export type HasType = SignatureDeclaration | VariableDeclaration | ParameterDeclaration | PropertySignature | PropertyDeclaration | TypePredicateNode | ParenthesizedTypeNode | TypeOperatorNode | MappedTypeNode | AssertionExpression | TypeAliasDeclaration | JSDocTypeExpression | JSDocNonNullableType | JSDocNullableType | JSDocOptionalType | JSDocVariadicType;
+    export type HasTypeArguments = CallExpression | NewExpression | TaggedTemplateExpression | JsxOpeningElement | JsxSelfClosingElement;
     export type HasInitializer = HasExpressionInitializer | ForStatement | ForInStatement | ForOfStatement | JsxAttribute;
     export type HasExpressionInitializer = VariableDeclaration | ParameterDeclaration | BindingElement | PropertySignature | PropertyDeclaration | PropertyAssignment | EnumMember;
     export interface NodeArray<T extends Node> extends ReadonlyArray<T>, TextRange {

tests/baselines/reference/api/typescript.d.ts

@@ -502,6 +502,7 @@ declare namespace ts {
     }
     export type HasJSDoc = ParameterDeclaration | CallSignatureDeclaration | ConstructSignatureDeclaration | MethodSignature | PropertySignature | ArrowFunction | ParenthesizedExpression | SpreadAssignment | ShorthandPropertyAssignment | PropertyAssignment | FunctionExpression | LabeledStatement | ExpressionStatement | VariableStatement | FunctionDeclaration | ConstructorDeclaration | MethodDeclaration | PropertyDeclaration | AccessorDeclaration | ClassLikeDeclaration | InterfaceDeclaration | TypeAliasDeclaration | EnumMember | EnumDeclaration | ModuleDeclaration | ImportEqualsDeclaration | IndexSignatureDeclaration | FunctionTypeNode | ConstructorTypeNode | JSDocFunctionType | ExportDeclaration | EndOfFileToken;
     export type HasType = SignatureDeclaration | VariableDeclaration | ParameterDeclaration | PropertySignature | PropertyDeclaration | TypePredicateNode | ParenthesizedTypeNode | TypeOperatorNode | MappedTypeNode | AssertionExpression | TypeAliasDeclaration | JSDocTypeExpression | JSDocNonNullableType | JSDocNullableType | JSDocOptionalType | JSDocVariadicType;
+    export type HasTypeArguments = CallExpression | NewExpression | TaggedTemplateExpression | JsxOpeningElement | JsxSelfClosingElement;
     export type HasInitializer = HasExpressionInitializer | ForStatement | ForInStatement | ForOfStatement | JsxAttribute;
     export type HasExpressionInitializer = VariableDeclaration | ParameterDeclaration | BindingElement | PropertySignature | PropertyDeclaration | PropertyAssignment | EnumMember;
     export interface NodeArray<T extends Node> extends ReadonlyArray<T>, TextRange {

tests/cases/fourslash/completionsConditionalMember.ts

@@ -0,0 +1,22 @@
+/// <reference path="fourslash.ts" />
+
+////declare function f<T extends string>(
+////  p: { a: T extends 'foo' ? { x: string } : { y: string } }
+////): void;
+////
+////f<'foo'>({ a: { /*1*/ } });
+////f<string>({ a: { /*2*/ } });
+
+verify.completions({
+  marker: '1',
+  exact: [{
+    name: 'x'
+  }]
+});
+
+verify.completions({
+  marker: '2',
+  exact: [{
+    name: 'y'
+  }]
+});

tests/cases/fourslash/completionsGenericIndexedAccess1.ts

@@ -0,0 +1,18 @@
+/// <reference path="fourslash.ts" />
+
+// #34825
+
+////interface Sample {
+////  addBook: { name: string, year: number }
+////}
+////
+////export declare function testIt<T>(method: T[keyof T]): any
+////testIt<Sample>({ /**/ });
+
+verify.completions({
+  marker: '',
+  exact: [
+    { name: 'name' },
+    { name: 'year' },
+  ]
+});

tests/cases/fourslash/completionsGenericIndexedAccess2.ts

@@ -0,0 +1,34 @@
+/// <reference path="fourslash.ts" />
+
+// #34825
+
+////export type GetMethodsForType<T, G extends string> = { [K in keyof T]:
+////  T[K] extends () => any ? { name: K, group: G, } : T[K] extends (s: infer U) => any ? { name: K, group: G, payload: U } : never }[keyof T];
+////
+////
+////class Sample {
+////  count = 0;
+////  books: { name: string, year: number }[] = []
+////  increment() {
+////      this.count++
+////      this.count++
+////  }
+////
+////  addBook(book: Sample["books"][0]) {
+////      this.books.push(book)
+////  }
+////}
+////export declare function testIt<T, G extends string>(): (input: any, method: GetMethodsForType<T, G>) => any
+////
+////
+////const t = testIt<Sample, "Sample">()
+////
+////const i = t(null, { name: "addBook", group: "Sample", payload: { /**/ } })
+
+verify.completions({
+  marker: '',
+  exact: [
+    { name: 'name' },
+    { name: 'year' },
+  ]
+});