3 files changed, 20 insertions, 4 deletions
diff --git a/clang/test/Modules/cxx-templates.cpp b/clang/test/Modules/cxx-templates.cpp
index fd6b4f5a2b1..ef4e4e420d0 100644
--- a/clang/test/Modules/cxx-templates.cpp
+++ b/clang/test/Modules/cxx-templates.cpp
@@ -105,8 +105,8 @@ void g() {
 
   TemplateInstantiationVisibility<char[1]> tiv1;
   TemplateInstantiationVisibility<char[2]> tiv2;
-  TemplateInstantiationVisibility<char[3]> tiv3; // expected-error {{must be imported from module 'cxx_templates_b_impl'}}
-  // expected-note@cxx-templates-b-impl.h:10 {{previous definition is here}}
+  TemplateInstantiationVisibility<char[3]> tiv3; // expected-error 2{{must be imported from module 'cxx_templates_b_impl'}}
+  // expected-note@cxx-templates-b-impl.h:10 2{{previous definition is here}}
   TemplateInstantiationVisibility<char[4]> tiv4;
 
   int &p = WithPartialSpecializationUse().f();
diff --git a/clang/test/Modules/hidden-definition.cpp b/clang/test/Modules/hidden-definition.cpp
new file mode 100644
index 00000000000..d06f9393458
--- /dev/null
+++ b/clang/test/Modules/hidden-definition.cpp
@@ -0,0 +1,16 @@
+// RUN: rm -rf %t
+// RUN: mkdir %t
+// RUN: echo 'struct X {}; struct Y : X { friend int f(Y); };' > %t/a.h
+// RUN: echo 'module a { header "a.h" }' > %t/map
+// RUN: %clang_cc1 -fmodules -x c++ -emit-module -fmodule-name=a %t/map -o %t/a.pcm
+// RUN: %clang_cc1 -fmodules -x c++ -verify -fmodule-file=%t/a.pcm %s -fno-modules-error-recovery
+
+struct X;
+struct Y;
+
+// Ensure that we can't use the definitions of X and Y, since we've not imported module a.
+Y *yp;
+X *xp = yp; // expected-error {{cannot initialize}}
+_Static_assert(!__is_convertible(Y*, X*), "");
+X &xr = *yp; // expected-error {{unrelated type}}
+int g(Y &y) { f(y); } // expected-error {{undeclared identifier 'f'}}
diff --git a/clang/test/Modules/submodules-merge-defs.cpp b/clang/test/Modules/submodules-merge-defs.cpp
index 12e3cadd531..23d1f5cfb12 100644
--- a/clang/test/Modules/submodules-merge-defs.cpp
+++ b/clang/test/Modules/submodules-merge-defs.cpp
@@ -22,7 +22,7 @@ A pre_a;
 #endif
 // expected-note@defs.h:1 +{{here}}
 extern class A pre_a2;
-int pre_use_a = use_a(pre_a2); // expected-error {{'A' must be imported}} expected-error {{'use_a' must be imported}}
+int pre_use_a = use_a(pre_a2); // expected-error 2{{'A' must be imported}} expected-error {{'use_a' must be imported}}
 // expected-note@defs.h:2 +{{here}}
 
 B::Inner2 pre_bi; // expected-error +{{must be imported}}
@@ -48,7 +48,7 @@ int pre_e = E(0); // expected-error {{must be imported}}
 // expected-note@defs.h:32 +{{here}}
 
 int pre_ff = F<int>().f(); // expected-error +{{must be imported}}
-int pre_fg = F<int>().g<int>(); // expected-error +{{must be imported}}
+int pre_fg = F<int>().g<int>(); // expected-error +{{must be imported}} expected-error 2{{expected}}
 // expected-note@defs.h:34 +{{here}}
 
 G::A pre_ga // expected-error +{{must be imported}}