fix: normalize "." and ".." in resolved module paths to dedupe modules (#1977)

ResolveModuleCallback builds the on-disk path for a relative specifier without collapsing "." and ".." segments, so the same file imported as "./x" from /a/b and as "../x" from /a/b/c lands under two different registry keys. stat() resolves the segments so both locate the file, but the differing keys make V8 compile and evaluate the module twice: two instances with separate state, and import.meta.dirname becomes "/a/b/c/.." for the ".." spelling. Normalize the resolved path before it becomes the registry key, the same way the HTTP branch canonicalizes through CanonicalizeHttpUrlKey. The pass is lexical and runs for every on-disk candidate kind, and is a no-op for already-canonical paths.

Author: adrian-niculescu

test-app/app/src/main/assets/app/esm-dedup/counter.mjs

@@ -0,0 +1,8 @@
+// Singleton module: an ES module is evaluated once, so every importer must
+// observe this same `state` object regardless of how the specifier spelled the
+// path to this file.
+export const state = { count: 0 };
+
+export function increment() {
+    state.count++;
+}

test-app/app/src/main/assets/app/esm-dedup/nested/viaParentDir.mjs

@@ -0,0 +1,6 @@
+// Reaches the same counter.mjs one directory up: "../counter.mjs".
+import { state, increment } from "../counter.mjs";
+
+increment();
+
+export const seenState = state;

test-app/app/src/main/assets/app/esm-dedup/viaSameDir.mjs

@@ -0,0 +1,6 @@
+// Reaches counter.mjs as a same-directory sibling: "./counter.mjs".
+import { state, increment } from "./counter.mjs";
+
+increment();
+
+export const seenState = state;

test-app/app/src/main/assets/app/tests/testESModules.mjs

@@ -61,4 +61,21 @@ describe("ES Modules", () => {
         (err) => { expect(err).toBeUndefined(); done(); }
       );
   });
+
+  it("resolves './x' and '../x' to a single shared module instance", (done) => {
+    Promise.all([
+      import("~/esm-dedup/viaSameDir.mjs"),
+      import("~/esm-dedup/nested/viaParentDir.mjs"),
+    ]).then(
+      ([sameDir, parentDir]) => {
+        // The same counter.mjs is reached as "./counter.mjs" and as
+        // "../counter.mjs"; it must be one module instance sharing one state
+        // object, incremented once per importer.
+        expect(sameDir.seenState).toBe(parentDir.seenState);
+        expect(sameDir.seenState.count).toBe(2);
+        done();
+      },
+      (err) => { expect(err).toBeUndefined(); done(); }
+    );
+  });
 });

test-app/runtime/src/main/cpp/ModuleInternalCallbacks.cpp

@@ -1380,6 +1380,14 @@ v8::MaybeLocal<v8::Module> ResolveModuleCallback(v8::Local<v8::Context> context,
         if (found) break;
     }
 
+    // Canonicalize "." / ".." segments so a file reached through different
+    // spellings (e.g. "./x" from /a/b and "../x" from /a/b/c both name /a/b/x)
+    // maps to one registry key and is compiled once. The HTTP branch
+    // canonicalizes via CanonicalizeHttpUrlKey.
+    if (found) {
+        absPath = NormalizeDotSegments(absPath);
+    }
+
     // 6) Handle special cases if file not found
     if (!found) {
         // Check for Node.js built-in modules