fix: handle dynamic imports with module aliases

Fixes #7403

When a module containing an alias (e.g. `module VS = VariantSpreads`) is
dynamically imported, the compiler now correctly extracts the original
module identifier from the Llet expression.

Author: cristianoc

CHANGELOG.md

@@ -35,6 +35,7 @@
 - Fix regression in pattern matching for optional fields containing variants. https://github.com/rescript-lang/rescript/pull/7440
 - Fix missing checks for duplicate literals in variants with payloads. https://github.com/rescript-lang/rescript/pull/7441
 - Fix printer removing private for empty record. https://github.com/rescript-lang/rescript/pull/7448
+- Fix: handle dynamic imports with module aliases. https://github.com/rescript-lang/rescript/pull/7452
 
 #### :house: Internal
 

compiler/core/lam_convert.ml

@@ -442,6 +442,22 @@ let convert (exports : Set_ident.t) (lam : Lambda.lambda) :
         in
         Lam.function_ ~attr ~arity:(List.length params) ~params
           ~body:(convert_aux body)
+    | Llet (_, _, _, Lprim (Pgetglobal id, args, _), _body) when dynamic_import
+      ->
+      (*
+        Normally `await M` produces (global M!)
+        but when M contains an alias such as `module VS = VariantSpreads`,
+        it produces something like this:
+      
+        (let (let/1202 = (global M!))
+              (makeblock [x;M;y;X] (field:x/0 let/1202)
+                ...)
+
+        Here, we need to extract the original module id from the Llet.
+      *)
+      may_depend may_depends (Lam_module_ident.of_ml ~dynamic_import id);
+      assert (args = []);
+      Lam.global_module ~dynamic_import id
     | Llet (kind, Pgenval, id, e, body) (*FIXME*) -> convert_let kind id e body
     | Lletrec (bindings, body) ->
       let bindings = Ext_list.map_snd bindings convert_aux in

tests/tests/src/DynamicImportModuleWithAlias.mjs

@@ -0,0 +1,12 @@
+// Generated by ReScript, PLEASE EDIT WITH CARE
+
+
+async function foo(z) {
+  let Utils = await import("./ModuleWithAlias.mjs");
+  return Utils.x + z | 0;
+}
+
+export {
+  foo,
+}
+/* No side effect */

tests/tests/src/DynamicImportModuleWithAlias.res

@@ -0,0 +1,5 @@
+let foo = async z => {
+  module Utils = await ModuleWithAlias
+
+  Utils.x + z
+}

tests/tests/src/ModuleWithAlias.mjs

@@ -0,0 +1,15 @@
+// Generated by ReScript, PLEASE EDIT WITH CARE
+
+
+let x = 12;
+
+let VS;
+
+let y = 13;
+
+export {
+  x,
+  VS,
+  y,
+}
+/* No side effect */

tests/tests/src/ModuleWithAlias.res

@@ -0,0 +1,5 @@
+let x = 12
+
+module VS = VariantSpreads
+
+let y = 13