[Modules TS] Module ownership semantics for redeclarations.

When declaring an entity in the "purview" of a module, it's never a
redeclaration of an entity in the purview of a default module or in no module
("in the global module"). Don't consider those other declarations as possible
redeclaration targets if they're not visible, and reject any cases where we
pick a prior visible declaration that violates this rule.

llvm-svn: 315251

1 files changed, 19 insertions, 0 deletions

diff --git a/clang/test/CXX/modules-ts/basic/basic.def.odr/p6/module-vs-global.cpp b/clang/test/CXX/modules-ts/basic/basic.def.odr/p6/module-vs-global.cpp
new file mode 100644
index 00000000000..f58506dd9c4
--- /dev/null
+++ b/clang/test/CXX/modules-ts/basic/basic.def.odr/p6/module-vs-global.cpp
@@ -0,0 +1,19 @@
+// RUN: rm -rf %t
+// RUN: %clang_cc1 -fmodules-ts -emit-module-interface -std=c++17 %S/global-vs-module.cpp -o %t -DNO_GLOBAL -DEXPORT
+// RUN: %clang_cc1 -fmodules-ts -verify -std=c++17 %s -fmodule-file=%t
+
+import M;
+
+extern int var; // expected-error {{declaration of 'var' in the global module follows declaration in module M}} expected-note@global-vs-module.cpp:38 {{previous}}
+int func(); // expected-error {{declaration of 'func' in the global module follows declaration in module M}} expected-note@global-vs-module.cpp:39 {{previous}}
+struct str; // expected-error {{declaration of 'str' in the global module follows declaration in module M}} expected-note@global-vs-module.cpp:40 {{previous}}
+using type = int;
+
+template<typename> extern int var_tpl; // expected-error {{declaration of 'var_tpl' in the global module follows declaration in module M}} expected-note@global-vs-module.cpp:43 {{previous}}
+template<typename> int func_tpl(); // expected-error {{declaration of 'func_tpl' in the global module follows declaration in module M}} expected-note@global-vs-module.cpp:45 {{previous}}
+template<typename> struct str_tpl; // expected-error {{declaration of 'str_tpl' in the global module follows declaration in module M}} expected-note@global-vs-module.cpp:46 {{previous}}
+template<typename> using type_tpl = int; // expected-error {{declaration of 'type_tpl' in the global module follows declaration in module M}} expected-note@global-vs-module.cpp:47 {{previous}}
+
+typedef int type;
+namespace ns { using ::func; }
+namespace ns_alias = ns;