Add ImportResolver interface and use it for global imports

src/shell-interface.h

@@ -129,20 +129,6 @@ struct ShellExternalInterface : ModuleRunner::ExternalInterface {
       wasm, [&](Table* table) { tables[table->name].resize(table->initial); });
   }
 
-  void importGlobals(std::map<Name, Literals>& globals, Module& wasm) override {
-    ModuleUtils::iterImportedGlobals(wasm, [&](Global* import) {
-      auto inst = getImportInstance(import);
-      auto* exportedGlobal = inst->wasm.getExportOrNull(import->base);
-      if (!exportedGlobal || exportedGlobal->kind != ExternalKind::Global) {
-        trap((std::stringstream()
-              << "importGlobals: unknown import: " << import->module.str << "."
-              << import->name.str)
-               .str());
-      }
-      globals[import->name] = inst->globals[*exportedGlobal->getInternalName()];
-    });
-  }
-
   Literal getImportedFunction(Function* import) override {
     // TODO: We should perhaps restrict the types with which the well-known
     // functions can be imported.

src/support/nullability.h

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2026 WebAssembly Community Group participants
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// Trivial wrappers to annotate the nullability of pointers.
+
+#ifndef _wasm_support_nullability
+#define _wasm_support_nullability
+
+#include <memory>
+#include <type_traits>
+
+namespace wasm::nullability {
+
+template<typename T, typename = void> struct is_pointer : std::false_type {};
+
+template<typename T>
+struct is_pointer<T, std::void_t<typename std::pointer_traits<T>::element_type>>
+  : std::true_type {};
+
+template<typename T> using Nullable = std::enable_if_t<is_pointer<T>::value, T>;
+
+template<typename T> using NonNull = std::enable_if_t<is_pointer<T>::value, T>;
+
+} // namespace wasm::nullability
+
+#endif // _wasm_support_nullability

src/tools/wasm-ctor-eval.cpp

@@ -36,6 +36,7 @@
 #include "support/colors.h"
 #include "support/file.h"
 #include "support/insert_ordered.h"
+#include "support/nullability.h"
 #include "support/small_set.h"
 #include "support/string.h"
 #include "support/topological_sort.h"
@@ -67,13 +68,37 @@ bool isNullableAndMutable(Expression* ref, Index fieldIndex) {
 // the output.
 #define RECOMMENDATION "\n       recommendation: "
 
+class EvallingModuleRunner;
+
+class EvallingImportResolver : public ImportResolver {
+public:
+  EvallingImportResolver(
+    std::map<Name, std::shared_ptr<EvallingModuleRunner>> linkedInstances,
+    ModuleRunnerBase<EvallingModuleRunner>::ExternalInterface*
+      externalInterface)
+    : externalInterface(externalInterface) {}
+
+  nullability::Nullable<Literals*> getGlobal(QualifiedName name,
+                                             Type type) const override {
+    externalInterface->trap("Accessed imported global");
+    return nullptr;
+  }
+
+private:
+  ModuleRunnerBase<EvallingModuleRunner>::ExternalInterface* externalInterface;
+};
+
 class EvallingModuleRunner : public ModuleRunnerBase<EvallingModuleRunner> {
 public:
   EvallingModuleRunner(
     Module& wasm,
     ExternalInterface* externalInterface,
     std::map<Name, std::shared_ptr<EvallingModuleRunner>> linkedInstances_ = {})
-    : ModuleRunnerBase(wasm, externalInterface, linkedInstances_) {}
+    : ModuleRunnerBase(wasm,
+                       externalInterface,
+                       std::make_shared<EvallingImportResolver>(
+                         linkedInstances_, externalInterface),
+                       linkedInstances_) {}
 
   Flow visitGlobalGet(GlobalGet* curr) {
     // Error on reads of imported globals.
@@ -147,19 +172,6 @@ std::unique_ptr<Module> buildEnvModule(Module& wasm) {
     }
   });
 
-  ModuleUtils::iterImportedGlobals(wasm, [&](Global* global) {
-    if (global->module == env->name) {
-      auto* copied = ModuleUtils::copyGlobal(global, *env);
-      copied->module = Name();
-      copied->base = Name();
-
-      Builder builder(*env);
-      copied->init = builder.makeConst(Literal::makeZero(global->type));
-      env->addExport(
-        builder.makeExport(global->base, copied->name, ExternalKind::Global));
-    }
-  });
-
   // create an exported memory with the same initial and max size
   ModuleUtils::iterImportedMemories(wasm, [&](Memory* memory) {
     if (memory->module == env->name) {
@@ -231,26 +243,6 @@ struct CtorEvalExternalInterface : EvallingModuleRunner::ExternalInterface {
     }
   }
 
-  void importGlobals(GlobalValueSet& globals, Module& wasm_) override {
-    ModuleUtils::iterImportedGlobals(wasm_, [&](Global* global) {
-      auto it = linkedInstances.find(global->module);
-      if (it != linkedInstances.end()) {
-        auto* inst = it->second.get();
-        auto* globalExport = inst->wasm.getExportOrNull(global->base);
-        if (!globalExport || globalExport->kind != ExternalKind::Global) {
-          throw FailToEvalException(std::string("importGlobals: ") +
-                                    global->module.toString() + "." +
-                                    global->base.toString());
-        }
-        globals[global->name] = inst->globals[*globalExport->getInternalName()];
-      } else {
-        throw FailToEvalException(std::string("importGlobals: ") +
-                                  global->module.toString() + "." +
-                                  global->base.toString());
-      }
-    });
-  }
-
   Literal getImportedFunction(Function* import) override {
     auto f = [import, this](const Literals& arguments) -> Flow {
       Name WASI("wasi_snapshot_preview1");
@@ -558,8 +550,8 @@ struct CtorEvalExternalInterface : EvallingModuleRunner::ExternalInterface {
   void applyGlobalsToModule() {
     if (!wasm->features.hasGC()) {
       // Without GC, we can simply serialize the globals in place as they are.
-      for (const auto& [name, values] : instance->globals) {
-        wasm->getGlobal(name)->init = getSerialization(values);
+      for (const auto& [name, values] : instance->allGlobals) {
+        wasm->getGlobal(name)->init = getSerialization(*values);
       }
       return;
     }
@@ -590,9 +582,9 @@ struct CtorEvalExternalInterface : EvallingModuleRunner::ExternalInterface {
       // for it. (If there is no value, then this is a new global we've added
       // during execution, for whom we've already set up a proper serialized
       // value when we created it.)
-      auto iter = instance->globals.find(oldGlobal->name);
-      if (iter != instance->globals.end()) {
-        oldGlobal->init = getSerialization(iter->second, name);
+      auto iter = instance->allGlobals.find(oldGlobal->name);
+      if (iter != instance->allGlobals.end()) {
+        oldGlobal->init = getSerialization(*iter->second, name);
       }
 
       // Add the global back to the module.

src/tools/wasm-shell.cpp

@@ -280,7 +280,7 @@ struct Shell {
       }
       auto& instance = it->second;
       try {
-        return instance->getExportedGlobal(get->name);
+        return instance->getExportedGlobalOrTrap(get->name);
       } catch (TrapException&) {
         return TrapResult{};
       } catch (...) {