[NFC] [Modules] Add a test for issue 81745

Although the root cause of
llvm#81745 shows not related to
modules, it should be good to add a regression test for that.

clang/test/Modules/pr81745.cppm

@@ -0,0 +1,23 @@
+// RUN: rm -rf %t
+// RUN: mkdir -p %t
+// RUN: split-file %s %t
+//
+// RUN: %clang_cc1 -std=c++20 %t/M.cppm  -triple=x86_64-linux-gnu \
+// RUN:     -emit-module-interface -o %t/M.pcm
+// RUN: %clang_cc1 -std=c++20 %t/foo.cpp -fprebuilt-module-path=%t \
+// RUN:      -triple=x86_64-linux-gnu  -emit-llvm -o - | FileCheck %t/foo.cpp
+
+//--- M.cppm
+export module M;
+export struct S1 {
+    consteval S1(int) {}
+};
+
+//--- foo.cpp
+import M;
+void foo() {
+    struct S2 { S1 s = 0; };
+    S2 s;
+}
+
+// CHECK-NOT: _ZNW1M2S1C1Ei