Merge pull request #15518 from vkurchatkin/empty-property

Allow indexed access to empty property

Author: mhegazy

src/compiler/checker.ts

@@ -7257,7 +7257,7 @@ namespace ts {
                 accessExpression && checkThatExpressionIsProperSymbolReference(accessExpression.argumentExpression, indexType, /*reportError*/ false) ?
                     getPropertyNameForKnownSymbolName((<Identifier>(<PropertyAccessExpression>accessExpression.argumentExpression).name).text) :
                     undefined;
-            if (propName) {
+            if (propName !== undefined) {
                 const prop = getPropertyOfType(objectType, propName);
                 if (prop) {
                     if (accessExpression) {

tests/baselines/reference/noImplicitAnyStringIndexerOnObject.errors.txt

@@ -4,4 +4,5 @@ tests/cases/compiler/noImplicitAnyStringIndexerOnObject.ts(1,9): error TS7017: E
 ==== tests/cases/compiler/noImplicitAnyStringIndexerOnObject.ts (1 errors) ====
     var x = {}["hello"];
             ~~~~~~~~~~~
-!!! error TS7017: Element implicitly has an 'any' type because type '{}' has no index signature.
+!!! error TS7017: Element implicitly has an 'any' type because type '{}' has no index signature.
+    var y: string = { '': 'foo' }[''];

tests/baselines/reference/noImplicitAnyStringIndexerOnObject.js

@@ -1,5 +1,7 @@
 //// [noImplicitAnyStringIndexerOnObject.ts]
-var x = {}["hello"];
+var x = {}["hello"];
+var y: string = { '': 'foo' }[''];
 
 //// [noImplicitAnyStringIndexerOnObject.js]
 var x = {}["hello"];
+var y = { '': 'foo' }[''];

tests/cases/compiler/noImplicitAnyStringIndexerOnObject.ts

@@ -1,3 +1,4 @@
 // @noimplicitany: true
 
-var x = {}["hello"];
+var x = {}["hello"];
+var y: string = { '': 'foo' }[''];