Enable method signature completion for object literals

src/harness/fourslashInterfaceImpl.ts

@@ -950,9 +950,35 @@ namespace FourSlashInterface {
     }
 
     export namespace Completion {
-        export import SortText = ts.Completions.SortText;
+        import SortTextType = ts.Completions.SortText;
+        export type SortText = SortTextType;
         export import CompletionSource = ts.Completions.CompletionSource;
 
+        export const SortText = {
+            // Presets
+            LocalDeclarationPriority: "10" as SortText,
+            LocationPriority: "11" as SortText,
+            OptionalMember: "12" as SortText,
+            MemberDeclaredBySpreadAssignment: "13" as SortText,
+            SuggestedClassMembers: "14" as SortText,
+            GlobalsOrKeywords: "15" as SortText,
+            AutoImportSuggestions: "16" as SortText,
+            JavascriptIdentifiers: "17" as SortText,
+
+            // Transformations
+            Deprecated(sortText: SortText): SortText {
+                return "z" + sortText as SortText;
+            },
+
+            ObjectLiteralProperty(presetSortText: SortText, symbolDisplayName: string): SortText {
+                return `${presetSortText}\0${symbolDisplayName}\0` as SortText;
+            },
+
+            AddIsSnippetSuffix(sortText: SortText): SortText {
+                return sortText + "1" as SortText;
+            },
+        };
+
         const functionEntry = (name: string): ExpectedCompletionEntryObject => ({
             name,
             kind: "function",

src/services/completions.ts

@@ -6,19 +6,31 @@ namespace ts.Completions {
 
     export type Log = (message: string) => void;
 
-    // NOTE: Make sure that each entry has the exact same number of digits
-    //       since many implementations will sort by string contents,
-    //       where "10" is considered less than "2".
-    export enum SortText {
-        LocalDeclarationPriority = "10",
-        LocationPriority = "11",
-        OptionalMember = "12",
-        MemberDeclaredBySpreadAssignment = "13",
-        SuggestedClassMembers = "14",
-        GlobalsOrKeywords = "15",
-        AutoImportSuggestions = "16",
-        JavascriptIdentifiers = "17",
-    }
+    export type SortText = string & { __sortText: any };
+    export const SortText = {
+        // Presets
+        LocalDeclarationPriority: "10" as SortText,
+        LocationPriority: "11" as SortText,
+        OptionalMember: "12" as SortText,
+        MemberDeclaredBySpreadAssignment: "13" as SortText,
+        SuggestedClassMembers: "14" as SortText,
+        GlobalsOrKeywords: "15" as SortText,
+        AutoImportSuggestions: "16" as SortText,
+        JavascriptIdentifiers: "17" as SortText,
+
+        // Transformations
+        Deprecated(sortText: SortText): SortText {
+            return "z" + sortText as SortText;
+        },
+
+        ObjectLiteralProperty(presetSortText: SortText, symbolDisplayName: string): SortText {
+            return `${presetSortText}\0${symbolDisplayName}\0` as SortText;
+        },
+
+        AddIsSnippetSuffix(sortText: SortText): SortText {
+            return sortText + "1" as SortText;
+        },
+    };
 
     /**
      * Special values for `CompletionInfo['source']` used to disambiguate
@@ -129,7 +141,6 @@ namespace ts.Completions {
 
     /**
      * Map from symbol index in `symbols` -> SymbolOriginInfo.
-     * Only populated for symbols that come from other modules.
      */
     type SymbolOriginInfoMap = Record<number, SymbolOriginInfo>;
 
@@ -767,7 +778,7 @@ namespace ts.Completions {
             }
             ({ insertText, isSnippet, importAdder, sourceDisplay } = entry);
             source = CompletionSource.ObjectLiteralMethodSnippet;
-            sortText = sortText + "1" as SortText;
+            sortText = SortText.AddIsSnippetSuffix(sortText);
             if (importAdder.hasFixes()) {
                 hasAction = true;
             }
@@ -1129,13 +1140,23 @@ namespace ts.Completions {
             case SyntaxKind.MethodSignature:
             case SyntaxKind.MethodDeclaration: {
                 const signatures = checker.getSignaturesOfType(type, SignatureKind.Call);
-                if (signatures.length > 1) {
+                if (signatures.length !== 1) {
                     // We don't support overloads in object literals.
                     return undefined;
                 }
-                const effectiveType = type.flags & TypeFlags.Union && (type as UnionType).types.length < 10
+                let effectiveType = type.flags & TypeFlags.Union && (type as UnionType).types.length < 10
                     ? checker.getUnionType((type as UnionType).types, UnionReduction.Subtype)
                     : type;
+                if (effectiveType.flags & TypeFlags.Union) {
+                    // Only offer the completion if there's a single function type component.
+                    const functionTypes = filter((effectiveType as UnionType).types, type => checker.getSignaturesOfType(type, SignatureKind.Call).length > 0);
+                    if (functionTypes.length === 1) {
+                        effectiveType = functionTypes[0];
+                    }
+                    else {
+                        return undefined;
+                    }
+                }
                 let typeNode = checker.typeToTypeNode(effectiveType, enclosingDeclaration, builderFlags, codefix.getNoopSymbolTrackerWithResolver({ program, host }));
                 if (!typeNode || !isFunctionTypeNode(typeNode)) {
                     return undefined;
@@ -1373,7 +1394,7 @@ namespace ts.Completions {
 
             const { name, needsConvertPropertyAccess } = info;
             const originalSortText = symbolToSortTextIdMap?.[getSymbolId(symbol)] ?? SortText.LocationPriority;
-            const sortText = (isDeprecated(symbol, typeChecker) ? "z" + originalSortText : originalSortText) as SortText;
+            const sortText = (isDeprecated(symbol, typeChecker) ? SortText.Deprecated(originalSortText) : originalSortText);
             const entry = createCompletionEntry(
                 symbol,
                 sortText,
@@ -2950,6 +2971,7 @@ namespace ts.Completions {
          * @returns true if 'symbols' was successfully populated; false otherwise.
          */
         function tryGetObjectLikeCompletionSymbols(): GlobalsSearch | undefined {
+            const symbolsStartIndex = symbols.length;
             const objectLikeContainer = tryGetObjectLikeCompletionContainer(contextToken);
             if (!objectLikeContainer) return GlobalsSearch.Continue;
 
@@ -3027,8 +3049,7 @@ namespace ts.Completions {
             }
             setSortTextToOptionalMember();
             if (objectLikeContainer.kind === SyntaxKind.ObjectLiteralExpression && preferences.includeCompletionsWithInsertText) {
-                // >> TODO: specify `symbols` range?
-                transformObjectLiteralMembersSortText();
+                transformObjectLiteralMembersSortText(symbolsStartIndex);
             }
 
             return GlobalsSearch.Success;
@@ -3568,9 +3589,9 @@ namespace ts.Completions {
             }
         }
 
-        function transformObjectLiteralMembersSortText(): void {
+        function transformObjectLiteralMembersSortText(start: number): void {
             const pastSymbolIds: Set<number> = new Set();
-            for (let i = 0; i < symbols.length; i++) {
+            for (let i = start; i < symbols.length; i++) {
                 const symbol = symbols[i];
                 const symbolId = getSymbolId(symbol);
                 if (pastSymbolIds.has(symbolId)) {
@@ -3588,7 +3609,7 @@ namespace ts.Completions {
                 if (displayName) {
                     const originalSortText = symbolToSortTextIdMap[symbolId] ?? SortText.LocationPriority;
                     const { name } = displayName;
-                    symbolToSortTextIdMap[symbolId] = `${originalSortText}\0${name}\0` as SortText;
+                    symbolToSortTextIdMap[symbolId] = SortText.ObjectLiteralProperty(originalSortText, name);
                 }
             }
         }

tests/cases/fourslash/completionsObjectLiteralMethod1.ts

@@ -41,12 +41,13 @@ verify.completions({
     includes: [
         {
             name: "bar",
-            sortText: `${completion.SortText.LocationPriority}\0bar\0` as completion.SortText,
+            sortText: completion.SortText.ObjectLiteralProperty(completion.SortText.LocationPriority, "bar"),
             insertText: undefined,
         },
         {
             name: "bar",
-            sortText: `${completion.SortText.LocationPriority}\0bar\0${1}` as completion.SortText,
+            sortText: completion.SortText.AddIsSnippetSuffix(
+                completion.SortText.ObjectLiteralProperty(completion.SortText.LocationPriority, "bar")),
             source: completion.CompletionSource.ObjectLiteralMethodSnippet,
             insertText: "bar(x: number): void {\n},",
         },
@@ -61,23 +62,25 @@ verify.completions({
     includes: [
         {
             name: "bar",
-            sortText: `${completion.SortText.LocationPriority}\0bar\0` as completion.SortText,
+            sortText: completion.SortText.ObjectLiteralProperty(completion.SortText.LocationPriority, "bar"),
             insertText: undefined,
         },
         {
             name: "bar",
-            sortText: `${completion.SortText.LocationPriority}\0bar\0${1}` as completion.SortText,
+            sortText: completion.SortText.AddIsSnippetSuffix(
+                completion.SortText.ObjectLiteralProperty(completion.SortText.LocationPriority, "bar")),
             source: completion.CompletionSource.ObjectLiteralMethodSnippet,
             insertText: "bar(x: number): void {\n},",
         },
         {
             name: "foo",
-            sortText: `${completion.SortText.LocationPriority}\0foo\0` as completion.SortText,
+            sortText: completion.SortText.ObjectLiteralProperty(completion.SortText.LocationPriority, "foo"),
             insertText: undefined,
         },
         {
             name: "foo",
-            sortText: `${completion.SortText.LocationPriority}\0foo\0${1}` as completion.SortText,
+            sortText: completion.SortText.AddIsSnippetSuffix(
+                completion.SortText.ObjectLiteralProperty(completion.SortText.LocationPriority, "foo")),
             source: completion.CompletionSource.ObjectLiteralMethodSnippet,
             insertText: "foo(x: string): string {\n},",
         },
@@ -92,7 +95,7 @@ verify.completions({
     exact: [
         {
             name: "buzz",
-            sortText: `${completion.SortText.LocationPriority}\0buzz\0` as completion.SortText,
+            sortText: completion.SortText.ObjectLiteralProperty(completion.SortText.LocationPriority, "buzz"),
             // no declaration insert text, because this property has overloads
             insertText: undefined,
         },
@@ -107,12 +110,13 @@ verify.completions({
     includes: [
         {
             name: "\"space bar\"",
-            sortText: `${completion.SortText.LocationPriority}\0${"\"space bar\""}\0` as completion.SortText,
+            sortText: completion.SortText.ObjectLiteralProperty(completion.SortText.LocationPriority, "\"space bar\""),
             insertText: undefined,
         },
         {
             name: "\"space bar\"",
-            sortText: `${completion.SortText.LocationPriority}\0${"\"space bar\""}\0${1}` as completion.SortText,
+            sortText: completion.SortText.AddIsSnippetSuffix(
+                completion.SortText.ObjectLiteralProperty(completion.SortText.LocationPriority, "\"space bar\"")),
             source: completion.CompletionSource.ObjectLiteralMethodSnippet,
             insertText: "\"space bar\"(): string {\n},",
         },
@@ -127,12 +131,13 @@ verify.completions({
     includes: [
         {
             name: "bar",
-            sortText: `${completion.SortText.LocationPriority}\0bar\0` as completion.SortText,
+            sortText: completion.SortText.ObjectLiteralProperty(completion.SortText.LocationPriority, "bar"),
             insertText: undefined,
         },
         {
             name: "bar",
-            sortText: `${completion.SortText.LocationPriority}\0bar\0${1}` as completion.SortText,
+            sortText: completion.SortText.AddIsSnippetSuffix(
+                completion.SortText.ObjectLiteralProperty(completion.SortText.LocationPriority, "bar")),
             source: completion.CompletionSource.ObjectLiteralMethodSnippet,
             isSnippet: true,
             insertText: "bar(x: number): void {\n    $0\n},",

tests/cases/fourslash/completionsObjectLiteralMethod2.ts

@@ -27,12 +27,13 @@ verify.completions({
     includes: [
         {
             name: "foo",
-            sortText: completion.SortText.LocationPriority,
+            sortText: completion.SortText.ObjectLiteralProperty(completion.SortText.LocationPriority, "foo"),
             insertText: undefined,
         },
         {
             name: "foo",
-            sortText: completion.SortText.OptionalMember,
+            sortText: completion.SortText.AddIsSnippetSuffix(
+                completion.SortText.ObjectLiteralProperty(completion.SortText.LocationPriority, "foo")),
             source: completion.CompletionSource.ObjectLiteralMethodSnippet,
             insertText: "foo(f: IFoo): void {\n},",
             hasAction: true,

tests/cases/fourslash/completionsObjectLiteralMethod3.ts

@@ -41,12 +41,13 @@ verify.completions({
     includes: [
         {
             name: "M",
-            sortText: completion.SortText.LocationPriority,
+            sortText: completion.SortText.ObjectLiteralProperty(completion.SortText.LocationPriority, "M"),
             insertText: undefined,
         },
         {
             name: "M",
-            sortText: completion.SortText.OptionalMember,
+            sortText: completion.SortText.AddIsSnippetSuffix(
+                completion.SortText.ObjectLiteralProperty(completion.SortText.LocationPriority, "M")),
             source: completion.CompletionSource.ObjectLiteralMethodSnippet,
             insertText: "M(x: number): void {\n},",
         },
@@ -61,7 +62,7 @@ verify.completions({
     includes: [
         {
             name: "M",
-            sortText: completion.SortText.LocationPriority,
+            sortText: completion.SortText.ObjectLiteralProperty(completion.SortText.LocationPriority, "M"),
             insertText: undefined,
         },
         // No signature completion because type of `M` is intersection type
@@ -76,7 +77,7 @@ verify.completions({
     exact: [
         {
             name: "M",
-            sortText: completion.SortText.LocationPriority,
+            sortText: completion.SortText.ObjectLiteralProperty(completion.SortText.LocationPriority, "M"),
             insertText: undefined,
         },
         // No signature completion because type of `M` is intersection type
@@ -91,34 +92,37 @@ verify.completions({
     includes: [
         {
             name: "M",
-            sortText: completion.SortText.OptionalMember,
+            sortText: completion.SortText.ObjectLiteralProperty(completion.SortText.OptionalMember, "M"),
             insertText: undefined,
         },
         {
             name: "M",
-            sortText: completion.SortText.OptionalMember,
+            sortText: completion.SortText.AddIsSnippetSuffix(
+                completion.SortText.ObjectLiteralProperty(completion.SortText.OptionalMember, "M")),
             source: completion.CompletionSource.ObjectLiteralMethodSnippet,
             insertText: "M(x: number): void {\n},",
         },
         {
             name: "N",
-            sortText: completion.SortText.LocationPriority,
+            sortText: completion.SortText.ObjectLiteralProperty(completion.SortText.LocationPriority, "N"),
             insertText: undefined,
         },
         {
             name: "N",
-            sortText: completion.SortText.OptionalMember,
+            sortText: completion.SortText.AddIsSnippetSuffix(
+                completion.SortText.ObjectLiteralProperty(completion.SortText.LocationPriority, "N")),
             source: completion.CompletionSource.ObjectLiteralMethodSnippet,
             insertText: "N(x: string): void {\n},",
         },
         {
             name: "O",
-            sortText: completion.SortText.OptionalMember,
+            sortText: completion.SortText.ObjectLiteralProperty(completion.SortText.OptionalMember, "O"),
             insertText: undefined,
         },
         {
             name: "O",
-            sortText: completion.SortText.OptionalMember,
+            sortText: completion.SortText.AddIsSnippetSuffix(
+                completion.SortText.ObjectLiteralProperty(completion.SortText.OptionalMember, "O")),
             source: completion.CompletionSource.ObjectLiteralMethodSnippet,
             insertText: "O(): void {\n},",
         },

tests/cases/fourslash/fourslash.ts

@@ -838,23 +838,22 @@ declare namespace completion {
     interface GlobalsPlusOptions {
         noLib?: boolean;
     }
-    export const enum SortText {
-        LocalDeclarationPriority = "10",
-        LocationPriority = "11",
-        OptionalMember = "12",
-        MemberDeclaredBySpreadAssignment = "13",
-        SuggestedClassMembers = "14",
-        GlobalsOrKeywords = "15",
-        AutoImportSuggestions = "16",
-        JavascriptIdentifiers = "17",
-        DeprecatedLocalDeclarationPriority = "18",
-        DeprecatedLocationPriority = "19",
-        DeprecatedOptionalMember = "20",
-        DeprecatedMemberDeclaredBySpreadAssignment = "21",
-        DeprecatedSuggestedClassMembers = "22",
-        DeprecatedGlobalsOrKeywords = "23",
-        DeprecatedAutoImportSuggestions = "24"
-    }
+    export type SortText = string & { __sortText: any };
+    export const SortText: {
+        LocalDeclarationPriority: SortText,
+        LocationPriority: SortText,
+        OptionalMember: SortText,
+        MemberDeclaredBySpreadAssignment: SortText,
+        SuggestedClassMembers: SortText,
+        GlobalsOrKeywords: SortText,
+        AutoImportSuggestions: SortText,
+        JavascriptIdentifiers: SortText,
+
+        Deprecated(sortText: SortText): SortText,
+        ObjectLiteralProperty(presetSortText: SortText, symbolDisplayName: string): SortText,
+        AddIsSnippetSuffix(sortText: SortText): SortText,
+    };
+
     export const enum CompletionSource {
         ThisProperty = "ThisProperty/",
         ClassMemberSnippet = "ClassMemberSnippet/",