Variables from different module declarations default to their declared type

src/compiler/checker.ts

@@ -7936,7 +7936,7 @@ namespace ts {
             const declaration = localOrExportSymbol.valueDeclaration;
             const defaultsToDeclaredType = !strictNullChecks || !declaration ||
                 declaration.kind === SyntaxKind.Parameter || isInAmbientContext(declaration) ||
-                getContainingFunctionOrSourceFile(declaration) !== getContainingFunctionOrSourceFile(node);
+                getContainingFunctionOrModule(declaration) !== getContainingFunctionOrModule(node);
             if (defaultsToDeclaredType && !(type.flags & TypeFlags.Narrowable)) {
                 return type;
             }

src/compiler/utilities.ts

@@ -840,11 +840,11 @@ namespace ts {
         }
     }
 
-    export function getContainingFunctionOrSourceFile(node: Node): FunctionLikeDeclaration | SourceFile {
+    export function getContainingFunctionOrModule(node: Node): Node {
         while (true) {
             node = node.parent;
-            if (isFunctionLike(node) || node.kind === SyntaxKind.SourceFile) {
-                return <FunctionLikeDeclaration | SourceFile>node;
+            if (isFunctionLike(node) || node.kind === SyntaxKind.ModuleDeclaration || node.kind === SyntaxKind.SourceFile) {
+                return node;
             }
         }
     }