[Clang] Apply exclude_from_explicit_instantiation to dllimport/dllexport

clang/lib/Sema/SemaDeclCXX.cpp

@@ -6551,6 +6551,8 @@ void Sema::checkClassLevelDLLAttribute(CXXRecordDecl *Class) {
     return;
   }
 
+  TemplateSpecializationKind TSK = Class->getTemplateSpecializationKind();
+
   if (Context.getTargetInfo().shouldDLLImportComdatSymbols() &&
       !ClassAttr->isInherited()) {
     // Diagnose dll attributes on members of class with dll attribute.
@@ -6561,6 +6563,11 @@ void Sema::checkClassLevelDLLAttribute(CXXRecordDecl *Class) {
       if (!MemberAttr || MemberAttr->isInherited() || Member->isInvalidDecl())
         continue;
 
+      if ((TSK == TSK_ExplicitInstantiationDeclaration ||
+           TSK == TSK_ExplicitInstantiationDefinition) &&
+          Member->hasAttr<ExcludeFromExplicitInstantiationAttr>())
+        continue;
+
       Diag(MemberAttr->getLocation(),
              diag::err_attribute_dll_member_of_dll_class)
           << MemberAttr << ClassAttr;
@@ -6583,8 +6590,6 @@ void Sema::checkClassLevelDLLAttribute(CXXRecordDecl *Class) {
       !ClassExported &&
       cast<DLLImportAttr>(ClassAttr)->wasPropagatedToBaseTemplate();
 
-  TemplateSpecializationKind TSK = Class->getTemplateSpecializationKind();
-
   // Ignore explicit dllexport on explicit class template instantiation
   // declarations, except in MinGW mode.
   if (ClassExported && !ClassAttr->isInherited() &&
@@ -6601,6 +6606,11 @@ void Sema::checkClassLevelDLLAttribute(CXXRecordDecl *Class) {
   // seem to be true in practice?
 
   for (Decl *Member : Class->decls()) {
+    if ((TSK == TSK_ExplicitInstantiationDeclaration ||
+         TSK == TSK_ExplicitInstantiationDefinition) &&
+        Member->hasAttr<ExcludeFromExplicitInstantiationAttr>())
+      continue;
+
     VarDecl *VD = dyn_cast<VarDecl>(Member);
     CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Member);
 

clang/test/CodeGenCXX/attr-exclude_from_explicit_instantiation.exclude_from_dllexport.cpp

@@ -0,0 +1,59 @@
+// RUN: %clang_cc1 -triple x86_64-win32 -fms-extensions -emit-llvm -o - %s | FileCheck %s --check-prefixes=MSC --implicit-check-not=to_be_
+// RUN: %clang_cc1 -triple x86_64-mingw                 -emit-llvm -o - %s | FileCheck %s --check-prefixes=GNU --implicit-check-not=to_be_
+// RUN: %clang_cc1 -triple x86_64-cygwin                -emit-llvm -o - %s | FileCheck %s --check-prefixes=GNU --implicit-check-not=to_be_
+
+// Test that __declspec(dllexport) doesn't instantiate entities marked with
+// the exclude_from_explicit_instantiation attribute unless marked as dllexport explicitly.
+
+#define EXCLUDE_FROM_EXPLICIT_INSTANTIATION __attribute__((exclude_from_explicit_instantiation))
+
+template <class T>
+struct C {
+  // This will be instantiated explicitly as an exported function because it
+  // inherits dllexport from the class instantiation.
+  void to_be_exported() noexcept;
+
+  // This will be instantiated implicitly as an exported function because it is
+  // marked as dllexport explicitly.
+  EXCLUDE_FROM_EXPLICIT_INSTANTIATION __declspec(dllexport) void to_be_exported_explicitly() noexcept;
+
+  // This will be instantiated implicitly but won't be exported.
+  EXCLUDE_FROM_EXPLICIT_INSTANTIATION void not_to_be_exported() noexcept;
+
+  // This won't be instantiated.
+  EXCLUDE_FROM_EXPLICIT_INSTANTIATION void not_to_be_instantiated() noexcept;
+};
+
+template <class T> void C<T>::to_be_exported() noexcept {}
+template <class T> void C<T>::to_be_exported_explicitly() noexcept {}
+template <class T> void C<T>::not_to_be_exported() noexcept {}
+template <class T> void C<T>::not_to_be_instantiated() noexcept {}
+
+// MSC: $"?to_be_exported@?$C@H@@QEAAXXZ" = comdat any
+// MSC: $"?to_be_exported_explicitly@?$C@H@@QEAAXXZ" = comdat any
+// MSC: $"?not_to_be_exported@?$C@H@@QEAAXXZ" = comdat any
+// GNU: $_ZN1CIiE14to_be_exportedEv = comdat any
+// GNU: $_ZN1CIiE25to_be_exported_explicitlyEv = comdat any
+// GNU: $_ZN1CIiE18not_to_be_exportedEv = comdat any
+
+// MSC: define weak_odr dso_local dllexport{{.*}} void @"?to_be_exported@?$C@H@@QEAAXXZ"
+// GNU: define weak_odr dso_local dllexport{{.*}} void @_ZN1CIiE14to_be_exportedEv
+template struct __declspec(dllexport) C<int>;
+
+void use() {
+  C<int> c;
+
+  // MSC: call void @"?to_be_exported_explicitly@?$C@H@@QEAAXXZ"
+  // GNU: call void @_ZN1CIiE25to_be_exported_explicitlyEv
+  c.to_be_exported_explicitly(); // implicitly instantiated here
+
+  // MSC: call void @"?not_to_be_exported@?$C@H@@QEAAXXZ"
+  // GNU: call void @_ZN1CIiE18not_to_be_exportedEv
+  c.not_to_be_exported(); // implicitly instantiated here
+};
+
+// MSC: define weak_odr dso_local dllexport{{.*}} void @"?to_be_exported_explicitly@?$C@H@@QEAAXXZ"
+// GNU: define weak_odr dso_local dllexport{{.*}} void @_ZN1CIiE25to_be_exported_explicitlyEv
+
+// MSC: define linkonce_odr dso_local void @"?not_to_be_exported@?$C@H@@QEAAXXZ"
+// GNU: define linkonce_odr dso_local void @_ZN1CIiE18not_to_be_exportedEv

clang/test/CodeGenCXX/attr-exclude_from_explicit_instantiation.exclude_from_dllimport.cpp

@@ -0,0 +1,58 @@
+// RUN: %clang_cc1 -triple x86_64-win32 -fms-extensions -emit-llvm -o - %s | FileCheck %s --check-prefixes=MSC --implicit-check-not=to_be_
+// RUN: %clang_cc1 -triple x86_64-mingw                 -emit-llvm -o - %s | FileCheck %s --check-prefixes=GNU --implicit-check-not=to_be_
+// RUN: %clang_cc1 -triple x86_64-cygwin                -emit-llvm -o - %s | FileCheck %s --check-prefixes=GNU --implicit-check-not=to_be_
+
+// Test that __declspec(dllimport) doesn't instantiate entities marked with
+// the exclude_from_explicit_instantiation attribute unless marked as dllimport explicitly.
+
+#define EXCLUDE_FROM_EXPLICIT_INSTANTIATION __attribute__((exclude_from_explicit_instantiation))
+
+template <class T>
+struct C {
+  // This will be instantiated explicitly as an imported function because it
+  // inherits dllimport from the class instantiation.
+  void to_be_imported() noexcept;
+
+  // This will be instantiated implicitly as an imported function because it is
+  // marked as dllimport explicitly.
+  EXCLUDE_FROM_EXPLICIT_INSTANTIATION __declspec(dllimport) void to_be_imported_explicitly() noexcept;
+
+  // This will be instantiated implicitly but won't be imported.
+  EXCLUDE_FROM_EXPLICIT_INSTANTIATION void not_to_be_imported() noexcept;
+
+  // This won't be instantiated.
+  EXCLUDE_FROM_EXPLICIT_INSTANTIATION void not_to_be_instantiated() noexcept;
+};
+
+template <class T> void C<T>::to_be_imported() noexcept {}
+template <class T> void C<T>::not_to_be_imported() noexcept {}
+template <class T> void C<T>::not_to_be_instantiated() noexcept {}
+
+// MSC: $"?not_to_be_imported@?$C@H@@QEAAXXZ" = comdat any
+// GNU: $_ZN1CIiE18not_to_be_importedEv = comdat any
+extern template struct __declspec(dllimport) C<int>;
+
+void use() {
+  C<int> c;
+
+  // MSC: call void @"?to_be_imported@?$C@H@@QEAAXXZ"
+  // GNU: call void @_ZN1CIiE14to_be_importedEv
+  c.to_be_imported();
+
+  // MSC: call void @"?to_be_imported_explicitly@?$C@H@@QEAAXXZ"
+  // GNU: call void @_ZN1CIiE25to_be_imported_explicitlyEv
+  c.to_be_imported_explicitly(); // implicitly instantiated here
+
+  // MSC: call void @"?not_to_be_imported@?$C@H@@QEAAXXZ"
+  // GNU: call void @_ZN1CIiE18not_to_be_importedEv
+  c.not_to_be_imported(); // implicitly instantiated here
+};
+
+// MSC: declare dllimport void @"?to_be_imported@?$C@H@@QEAAXXZ"
+// GNU: declare dllimport void @_ZN1CIiE14to_be_importedEv
+
+// MSC: declare dllimport void @"?to_be_imported_explicitly@?$C@H@@QEAAXXZ"
+// GNU: declare dllimport void @_ZN1CIiE25to_be_imported_explicitlyEv
+
+// MSC: define linkonce_odr dso_local void @"?not_to_be_imported@?$C@H@@QEAAXXZ"
+// GNU: define linkonce_odr dso_local void @_ZN1CIiE18not_to_be_importedEv