Fix name collision with import in generated code (#688)

Author: timostamm

packages/protobuf-test/extra/name-clash.proto

@@ -15,6 +15,13 @@
 syntax = "proto3";
 package spec;
 
+import "extra/example.proto";
+
+// This message class will clash with the imported message class
+message User {
+  docs.User u = 1; // Reference the import with the same name to trigger a clash
+}
+
 message ReservedPropertyNames {
     message BuiltIn {
         string constructor = 2; // built-in constructor()

packages/protobuf-test/src/gen/js/extra/name-clash_pb.d.ts

@@ -48,6 +48,19 @@ describe("file exportDecl", () => {
     expect(lines).toStrictEqual(["export const SomeEnum = 123;"]);
   });
 
+  test("forces import with same name to be aliased", async () => {
+    const lines = await testGenerate((f) => {
+      f.print(f.import("Foo", "pkg"));
+      f.print(f.exportDecl("const", "Foo"), " = 123;");
+    });
+    expect(lines).toStrictEqual([
+      `import { Foo as Foo$1 } from "pkg";`,
+      ``,
+      `Foo$1`,
+      `export const Foo = 123;`,
+    ]);
+  });
+
   async function testGenerate(
     gen: (
       f: GeneratedFile,

packages/protobuf-test/src/gen/js/extra/name-clash_pb.js

@@ -431,18 +431,25 @@ function processImports(
 
   // Walk through all symbols used and populate the collections above.
   for (const s of el) {
-    if (typeof s != "object" || s.kind !== "es_symbol") {
+    if (typeof s != "object") {
       continue;
     }
-    symbolToIdentifier.set(s.id, s.name);
-    if (!s.typeOnly) {
-      // a symbol is only type-imported as long as all uses are type-only
-      symbolToIsValue.set(s.id, true);
-    }
-    if (s.from === importerPath) {
-      identifiersTaken.add(s.name);
-    } else {
-      foreignSymbols.push(s);
+    switch (s.kind) {
+      case "es_symbol":
+        symbolToIdentifier.set(s.id, s.name);
+        if (!s.typeOnly) {
+          // a symbol is only type-imported as long as all uses are type-only
+          symbolToIsValue.set(s.id, true);
+        }
+        if (s.from === importerPath) {
+          identifiersTaken.add(s.name);
+        } else {
+          foreignSymbols.push(s);
+        }
+        break;
+      case "es_export_stmt":
+        identifiersTaken.add(s.name);
+        break;
     }
   }