TypeScriptToLua · ChouUn · Feb 26, 2026 · Feb 27, 2026
diff --git a/src/transpilation/resolve.ts b/src/transpilation/resolve.ts
@@ -31,6 +31,7 @@ class ResolutionContext {
 
     public diagnostics: ts.Diagnostic[] = [];
     public resolvedFiles = new Map<string, ProcessedFile>();
+    private realPathMap = new Map<string, string>();
 
     constructor(
         public readonly program: ts.Program,
@@ -88,19 +89,42 @@ class ResolutionContext {
 
         if (!dependencyPath) return this.couldNotResolveImport(required, file);
 
+        // Canonicalize symlink paths to avoid bundling the same physical file multiple times
+        const canonicalPath = this.canonicalizeDependencyPath(dependencyPath);
+
         if (this.options.tstlVerbose) {
-            console.log(`Resolved ${required.requirePath} to ${normalizeSlashes(dependencyPath)}`);
+            console.log(`Resolved ${required.requirePath} to ${normalizeSlashes(canonicalPath)}`);
         }
 
-        this.processDependency(dependencyPath);
+        this.processDependency(canonicalPath);
         // Figure out resolved require path and dependency output path
-        if (shouldRewriteRequires(dependencyPath, this.program)) {
-            const resolvedRequire = getEmitPathRelativeToOutDir(dependencyPath, this.program);
+        if (shouldRewriteRequires(canonicalPath, this.program)) {
+            const resolvedRequire = getEmitPathRelativeToOutDir(canonicalPath, this.program);
             replaceRequireInCode(file, required, resolvedRequire, this.options.extension);
             replaceRequireInSourceMap(file, required, resolvedRequire, this.options.extension);
         }
     }
 
+    /**
+     * Canonicalize dependency path by resolving symlinks.
+     * If the same physical file was already seen under a different path,
+     * return the first-seen path to ensure consistent module keys in bundles.
+     */
+    private canonicalizeDependencyPath(dependencyPath: string): string {
+        let realPath: string;
+        try {
+            realPath = fs.realpathSync(dependencyPath);
+        } catch {
+            return dependencyPath;
+        }
+
+        const existing = this.realPathMap.get(realPath);
+        if (existing !== undefined) return existing;
+
+        this.realPathMap.set(realPath, dependencyPath);
+        return dependencyPath;
+    }
+
     private resolveDependencyPathsWithPlugins(requiringFile: ProcessedFile, dependency: string) {
         const requiredFromLuaFile = requiringFile.fileName.endsWith(".lua");
         for (const plugin of this.plugins) {

diff --git a/test/transpile/module-resolution.spec.ts b/test/transpile/module-resolution.spec.ts
@@ -1,4 +1,5 @@
 import * as path from "path";
+import * as fs from "fs";
 import * as tstl from "../../src";
 import * as util from "../util";
 import * as ts from "typescript";
@@ -383,6 +384,50 @@ describe("dependency with complicated inner structure", () => {
     });
 });
 
+describe("symlinked dependency deduplication", () => {
+    const projectPath = path.resolve(__dirname, "module-resolution", "project-with-symlinked-dependency");
+    const tsConfigPath = path.join(projectPath, "tsconfig.json");
+    const mainFilePath = path.join(projectPath, "main.ts");
+    const symlinkPath = path.join(projectPath, "node_modules", "shared-lib");
+
+    beforeAll(() => {
+        // Dynamically create symlink to avoid git symlink portability issues
+        const symlinkDir = path.dirname(symlinkPath);
+        if (!fs.existsSync(symlinkDir)) {
+            fs.mkdirSync(symlinkDir, { recursive: true });
+        }
+        if (!fs.existsSync(symlinkPath)) {
+            fs.symlinkSync(path.join(projectPath, "shared-lib"), symlinkPath, "junction");
+        }
+    });
+
+    afterAll(() => {
+        if (fs.existsSync(symlinkPath) && fs.lstatSync(symlinkPath).isSymbolicLink()) {
+            fs.unlinkSync(symlinkPath);
+        }
+    });
+
+    test("bundle should not contain duplicate files from symlinked dependencies", () => {
+        const mainFile = path.join(projectPath, "main.ts");
+        const { transpiledFiles } = util
+            .testProject(tsConfigPath)
+            .setMainFileName(mainFilePath)
+            .setOptions({ luaBundle: "bundle.lua", luaBundleEntry: mainFile })
+            .expectToEqual({
+                directResult: "Hello, World",
+                indirectResult: "Hello, World, welcome!",
+            })
+            .getLuaResult();
+
+        expect(transpiledFiles).toHaveLength(1);
+        const lua = transpiledFiles[0].lua!;
+        // shared-lib is used by both main.ts (directly) and consumer (indirectly via symlink),
+        // but should only appear once in the bundle
+        const moduleEntries = (lua.match(/\["[^"]*shared-lib[^"]*"\]\s*=\s*function/g) ?? []).length;
+        expect(moduleEntries).toBe(1);
+    });
+});
+
 test("module resolution should not try to resolve @noResolution annotation", () => {
     util.testModule`
         import * as json from "json";

diff --git a/test/transpile/module-resolution/project-with-symlinked-dependency/main.ts b/test/transpile/module-resolution/project-with-symlinked-dependency/main.ts
@@ -0,0 +1,5 @@
+import * as sharedLib from "shared-lib";
+import * as consumer from "consumer";
+
+export const directResult = sharedLib.greet("World");
+export const indirectResult = consumer.welcome("World");
diff --git a/test/transpile/module-resolution/project-with-symlinked-dependency/shared-lib/index.d.ts b/test/transpile/module-resolution/project-with-symlinked-dependency/shared-lib/index.d.ts
@@ -0,0 +1,2 @@
+/** @noSelfInFile */
+export declare function greet(name: string): string;
diff --git a/test/transpile/module-resolution/project-with-symlinked-dependency/shared-lib/index.lua b/test/transpile/module-resolution/project-with-symlinked-dependency/shared-lib/index.lua
@@ -0,0 +1,5 @@
+return {
+    greet = function(name)
+        return "Hello, " .. name
+    end
+}
diff --git a/test/transpile/module-resolution/project-with-symlinked-dependency/tsconfig.json b/test/transpile/module-resolution/project-with-symlinked-dependency/tsconfig.json
@@ -0,0 +1,10 @@
+{
+    "compilerOptions": {
+        "strict": true,
+        "moduleResolution": "Node",
+        "target": "esnext",
+        "lib": ["esnext"],
+        "types": [],
+        "rootDir": "."
+    }
+}
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		/** @noSelfInFile */
		export declare function greet(name: string): string;