Add ValueModule as a valid object literal type, as they are immutable

src/compiler/checker.ts

@@ -6249,7 +6249,7 @@ namespace ts {
         }
 
         function getImplicitIndexTypeOfType(type: Type, kind: IndexKind): Type {
-            if (isObjectLiteralType(type)) {
+            if (isObjectTypeWithInferableIndex(type)) {
                 const propTypes: Type[] = [];
                 for (const prop of getPropertiesOfType(type)) {
                     if (kind === IndexKind.String || isNumericLiteralName(prop.escapedName)) {
@@ -9800,7 +9800,7 @@ namespace ts {
                     // if T is related to U.
                     return kind === IndexKind.String && isRelatedTo(getTemplateTypeFromMappedType(<MappedType>source), targetInfo.type, reportErrors);
                 }
-                if (isObjectLiteralType(source)) {
+                if (isObjectTypeWithInferableIndex(source)) {
                     let related = Ternary.True;
                     if (kind === IndexKind.String) {
                         const sourceNumberInfo = getIndexInfoOfType(source, IndexKind.Number);
@@ -10313,11 +10313,11 @@ namespace ts {
         }
 
         /**
-         * Return true if type was inferred from an object literal or written as an object type literal
+         * Return true if type was inferred from an object literal, written as an object type literal, or is the shape of a module
          * with no call or construct signatures.
          */
-        function isObjectLiteralType(type: Type) {
-            return type.symbol && (type.symbol.flags & (SymbolFlags.ObjectLiteral | SymbolFlags.TypeLiteral)) !== 0 &&
+        function isObjectTypeWithInferableIndex(type: Type) {
+            return type.symbol && (type.symbol.flags & (SymbolFlags.ObjectLiteral | SymbolFlags.TypeLiteral | SymbolFlags.ValueModule)) !== 0 &&
                 getSignaturesOfType(type, SignatureKind.Call).length === 0 &&
                 getSignaturesOfType(type, SignatureKind.Construct).length === 0;
         }

tests/baselines/reference/inferredIndexerOnNamespaceImport.js

@@ -0,0 +1,28 @@
+//// [tests/cases/compiler/inferredIndexerOnNamespaceImport.ts] ////
+
+//// [foo.ts]
+export const x = 3;
+export const y = 5;
+
+//// [bar.ts]
+import * as foo from "./foo";
+
+function f(map: { [k: string]: number }) {
+  // ...
+}
+
+f(foo);
+
+//// [foo.js]
+"use strict";
+exports.__esModule = true;
+exports.x = 3;
+exports.y = 5;
+//// [bar.js]
+"use strict";
+exports.__esModule = true;
+var foo = require("./foo");
+function f(map) {
+    // ...
+}
+f(foo);

tests/baselines/reference/inferredIndexerOnNamespaceImport.symbols

@@ -0,0 +1,23 @@
+=== tests/cases/compiler/foo.ts ===
+export const x = 3;
+>x : Symbol(x, Decl(foo.ts, 0, 12))
+
+export const y = 5;
+>y : Symbol(y, Decl(foo.ts, 1, 12))
+
+=== tests/cases/compiler/bar.ts ===
+import * as foo from "./foo";
+>foo : Symbol(foo, Decl(bar.ts, 0, 6))
+
+function f(map: { [k: string]: number }) {
+>f : Symbol(f, Decl(bar.ts, 0, 29))
+>map : Symbol(map, Decl(bar.ts, 2, 11))
+>k : Symbol(k, Decl(bar.ts, 2, 19))
+
+  // ...
+}
+
+f(foo);
+>f : Symbol(f, Decl(bar.ts, 0, 29))
+>foo : Symbol(foo, Decl(bar.ts, 0, 6))
+

tests/baselines/reference/inferredIndexerOnNamespaceImport.types

@@ -0,0 +1,26 @@
+=== tests/cases/compiler/foo.ts ===
+export const x = 3;
+>x : 3
+>3 : 3
+
+export const y = 5;
+>y : 5
+>5 : 5
+
+=== tests/cases/compiler/bar.ts ===
+import * as foo from "./foo";
+>foo : typeof foo
+
+function f(map: { [k: string]: number }) {
+>f : (map: { [k: string]: number; }) => void
+>map : { [k: string]: number; }
+>k : string
+
+  // ...
+}
+
+f(foo);
+>f(foo) : void
+>f : (map: { [k: string]: number; }) => void
+>foo : typeof foo
+

tests/cases/compiler/inferredIndexerOnNamespaceImport.ts

@@ -0,0 +1,12 @@
+// @filename: foo.ts
+export const x = 3;
+export const y = 5;
+
+// @filename: bar.ts
+import * as foo from "./foo";
+
+function f(map: { [k: string]: number }) {
+  // ...
+}
+
+f(foo);