[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, 55 insertions, 0 deletions

diff --git a/clang/test/CXX/modules-ts/basic/basic.def.odr/p6/global-vs-module.cpp b/clang/test/CXX/modules-ts/basic/basic.def.odr/p6/global-vs-module.cpp
new file mode 100644
index 00000000000..cceca5106ca
--- /dev/null
+++ b/clang/test/CXX/modules-ts/basic/basic.def.odr/p6/global-vs-module.cpp
@@ -0,0 +1,55 @@
+// RUN: %clang_cc1 -fmodules-ts -verify -std=c++17 %s 
+// RUN: %clang_cc1 -fmodules-ts -verify -std=c++17 %s -DEXPORT
+// RUN: %clang_cc1 -fmodules-ts -verify -std=c++17 %s -DUSING
+
+#ifndef NO_GLOBAL
+extern int var; // expected-note {{previous declaration is here}}
+int func(); // expected-note {{previous declaration is here}}
+struct str; // expected-note {{previous declaration is here}}
+using type = int;
+
+template<typename> extern int var_tpl; // expected-note {{previous declaration is here}}
+template<typename> int func_tpl(); // expected-note-re {{{{previous declaration is here|target of using declaration}}}}
+template<typename> struct str_tpl; // expected-note {{previous declaration is here}}
+template<typename> using type_tpl = int; // expected-note {{previous declaration is here}}
+
+typedef int type;
+namespace ns { using ::func; }
+namespace ns_alias = ns;
+#endif
+
+export module M;
+
+#ifdef USING
+using ::var;
+using ::func;
+using ::str;
+using ::type;
+using ::var_tpl;
+using ::func_tpl; // expected-note {{using declaration}}
+using ::str_tpl;
+using ::type_tpl;
+#endif
+
+#ifdef EXPORT
+export {
+#endif
+
+extern int var; // expected-error {{declaration of 'var' in module M follows declaration in the global module}}
+int func(); // expected-error {{declaration of 'func' in module M follows declaration in the global module}}
+struct str; // expected-error {{declaration of 'str' in module M follows declaration in the global module}}
+using type = int;
+
+template<typename> extern int var_tpl; // expected-error {{declaration of 'var_tpl' in module M follows declaration in the global module}}
+// FIXME: Is this the right diagnostic in the -DUSING case?
+template<typename> int func_tpl(); // expected-error-re {{{{declaration of 'func_tpl' in module M follows declaration in the global module|conflicts with target of using declaration}}}}
+template<typename> struct str_tpl; // expected-error {{declaration of 'str_tpl' in module M follows declaration in the global module}}
+template<typename> using type_tpl = int; // expected-error {{declaration of 'type_tpl' in module M follows declaration in the global module}}
+
+typedef int type;
+namespace ns { using ::func; }
+namespace ns_alias = ns;
+
+#ifdef EXPORT
+}
+#endif