From 8a1fcf1fe68b2dd119b9b521863aabdf3457406d Mon Sep 17 00:00:00 2001
From: Tom <26638278+tomblind@users.noreply.github.com>
Date: Sun, 14 Apr 2019 08:09:49 -0600
Subject: [PATCH] Fixed merging module into interface

---
 src/LuaTransformer.ts     | 13 +++++++++----
 test/unit/modules.spec.ts | 10 ++++++++++
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/src/LuaTransformer.ts b/src/LuaTransformer.ts
index eede8ed9e..ccb629938 100644
--- a/src/LuaTransformer.ts
+++ b/src/LuaTransformer.ts
@@ -1300,10 +1300,15 @@ export class LuaTransformer {
 
         const symbol = this.checker.getSymbolAtLocation(statement.name);
         const hasExports = symbol !== undefined && this.checker.getExportsOfModule(symbol).length > 0;
-        const isFirstDeclaration = symbol !== undefined
-            && symbol.declarations[0] === statement
-            // TS allows an empty namespace before a class of the same name
-            && symbol.declarations.findIndex(d => ts.isClassLike(d)) === -1;
+
+        // This is NOT the first declaration if:
+        // - declared as a module before this (ignore interfaces with same name)
+        // - declared as a class or function at all (TS requires these to be before module, unless module is empty)
+        const isFirstDeclaration =
+            symbol === undefined
+            || (symbol.declarations.findIndex(d => ts.isClassLike(d) || ts.isFunctionDeclaration(d)) === -1
+                && statement === symbol.declarations.find(ts.isModuleDeclaration));
+
         if (isFirstDeclaration) {
             const isExported = (ts.getCombinedModifierFlags(statement) & ts.ModifierFlags.Export) !== 0;
             if (isExported && this.currentNamespace) {
diff --git a/test/unit/modules.spec.ts b/test/unit/modules.spec.ts
index c02f052de..6da420d9e 100644
--- a/test/unit/modules.spec.ts
+++ b/test/unit/modules.spec.ts
@@ -63,3 +63,13 @@ test("Access this in module", () => {
     const code = `return M.bar();`;
     expect(util.transpileAndExecute(code, undefined, undefined, header)).toBe("foobar");
 });
+
+test("Module merged with interface", () => {
+    const header = `
+        interface Foo {}
+        module Foo {
+            export function bar() { return "foobar"; }
+        }`;
+    const code = `return Foo.bar();`;
+    expect(util.transpileAndExecute(code, undefined, undefined, header)).toBe("foobar");
+});