diff --git a/.vscode/launch.json b/.vscode/launch.json
index f62389b5..51da5601 100644
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -21,6 +21,10 @@
             "request": "launch",
             "name": "clice_test",
             "program": "${workspaceFolder}/build/bin/clice_test",
+            "args": [
+                "--test-dir=/home/ykiko/C++/clice2/tests/Source",
+                "--gtest_filter=clice.Compiler"
+            ],
             "cwd": "${workspaceFolder}"
         }
     ]
diff --git a/deps/llvm b/deps/llvm
index 74b7c749..68cd2926 160000
--- a/deps/llvm
+++ b/deps/llvm
@@ -1 +1 @@
-Subproject commit 74b7c749705a62380a58746ead5f7a4cbff74fae
+Subproject commit 68cd2926c6c0333dd8ee1fc9ac35ab492eedd59c
diff --git a/include/Compiler/Resolver.h b/include/Compiler/Resolver.h
index 4d31d8e8..dcc79489 100644
--- a/include/Compiler/Resolver.h
+++ b/include/Compiler/Resolver.h
@@ -19,6 +19,8 @@ public:
 
     clang::QualType resolve(clang::QualType type);
 
+    // TODO:
+    // use a relative clear way to resolve `UnresolvedLookupExpr`.
 private:
     clang::Sema& sema;
 };
diff --git a/src/Compiler/Preamble.cpp b/src/Compiler/Preamble.cpp
index 7d7f413b..f9ec7c0c 100644
--- a/src/Compiler/Preamble.cpp
+++ b/src/Compiler/Preamble.cpp
@@ -7,7 +7,9 @@ public:
     std::optional<clang::syntax::TokenCollector> collector;
 
 public:
-    void BeforeExecute(clang::CompilerInstance& CI) override { collector.emplace(CI.getPreprocessor()); }
+    void BeforeExecute(clang::CompilerInstance& CI) override {
+        collector.emplace(CI.getPreprocessor());
+    }
 
     void AfterExecute(clang::CompilerInstance& CI) override {
         auto tokens = std::move(collector.value()).consume();
diff --git a/tests/Source/ModuleScanner/A.cppm b/tests/Source/ModuleScanner/A.cppm
new file mode 100644
index 00000000..0db46de1
--- /dev/null
+++ b/tests/Source/ModuleScanner/A.cppm
@@ -0,0 +1,5 @@
+export module A;
+
+export int f() {
+    return 42;
+}
diff --git a/tests/Source/ModuleScanner/B.cppm b/tests/Source/ModuleScanner/B.cppm
new file mode 100644
index 00000000..8866f49d
--- /dev/null
+++ b/tests/Source/ModuleScanner/B.cppm
@@ -0,0 +1,3 @@
+export module B;
+
+import A;
\ No newline at end of file
diff --git a/tests/Source/ModuleScanner/C.cppm b/tests/Source/ModuleScanner/C.cppm
new file mode 100644
index 00000000..652cbd44
--- /dev/null
+++ b/tests/Source/ModuleScanner/C.cppm
@@ -0,0 +1,3 @@
+export module C;
+
+import A;
\ No newline at end of file
diff --git a/tests/Source/ModuleScanner/D.cppm b/tests/Source/ModuleScanner/D.cppm
new file mode 100644
index 00000000..080d121a
--- /dev/null
+++ b/tests/Source/ModuleScanner/D.cppm
@@ -0,0 +1,7 @@
+import B;
+import C;
+
+int main() {
+    int x = 42;
+    return 42;
+}