fix(38463): show completions for index access properties

src/services/stringCompletions.ts

@@ -223,9 +223,7 @@ namespace ts.Completions.StringCompletions {
     function stringLiteralCompletionsFromProperties(type: Type | undefined): StringLiteralCompletionsFromProperties | undefined {
         return type && {
             kind: StringLiteralCompletionKind.Properties,
-            symbols: type.getApparentProperties().filter(prop =>
-                !isPrivateIdentifierPropertyDeclaration(
-                    isTransientSymbol(prop) && prop.syntheticOrigin ? prop.syntheticOrigin.valueDeclaration : prop.valueDeclaration)),
+            symbols: filter(type.getApparentProperties(), prop => !(prop.valueDeclaration && isPrivateIdentifierPropertyDeclaration(prop.valueDeclaration))),
             hasIndexSignature: hasIndexSignature(type)
         };
     }

tests/cases/fourslash/completionForStringLiteral14.ts

@@ -0,0 +1,18 @@
+/// <reference path='fourslash.ts'/>
+
+////interface Foo {
+////    a: string;
+////    b: boolean;
+////    c: number;
+////}
+////type Bar = Record<keyof Foo, any>["[|/**/|]"];
+
+const replacementSpan = test.ranges()[0]
+verify.completions({
+    marker: "",
+    exact: [
+        { name: "a", replacementSpan },
+        { name: "b", replacementSpan },
+        { name: "c", replacementSpan }
+    ]
+});

tests/cases/fourslash/completionForStringLiteral15.ts

@@ -0,0 +1,12 @@
+/// <reference path='fourslash.ts'/>
+
+////let x: { [_ in "foo"]: string } = {
+////    "[|/**/|]"
+////}
+
+verify.completions({
+    marker: "",
+    exact: [
+        { name: "foo", replacementSpan: test.ranges()[0] }
+    ]
+});