MS ABI: Propagate class-level DLL attributes to class template specialization bases (PR11170)

Consider the following code:

  template <typename T> class Base {};
  class __declspec(dllexport) class Derived : public Base<int> {}

When the base of an exported or imported class is a class template
specialization, MSVC will propagate the dll attribute to the base.
In the example code, Base<int> becomes a dllexported class.

This commit makes Clang do the proopagation when the base hasn't been
instantiated yet, and warns about it being unsupported otherwise.
This is different from MSVC, which allows changing a specialization
back and forth between dllimport and dllexport and seems to let the
last one win. Changing the dll attribute after instantiation would be
hard for us, and doesn't seem to come up in practice, so I think this
is a reasonable limitation to have.

MinGW doesn't do this kind of propagation.

Differential Revision: http://reviews.llvm.org/D4264

llvm-svn: 211725

1 files changed, 99 insertions, 0 deletions

diff --git a/clang/test/CodeGenCXX/dllimport.cpp b/clang/test/CodeGenCXX/dllimport.cpp
index 3f3c34b8a25..63b119277ec 100644
--- a/clang/test/CodeGenCXX/dllimport.cpp
+++ b/clang/test/CodeGenCXX/dllimport.cpp
@@ -662,3 +662,102 @@ template <> struct __declspec(dllimport) ExplicitlySpecializedClassTemplate<void
 USEMEMFUNC(ExplicitlySpecializedClassTemplate<void*>, f);
 // M32-DAG: {{declare|define available_externally}} dllimport x86_thiscallcc void @"\01?f@?$ExplicitlySpecializedClassTemplate@PAX@@QAEXXZ"
 // G32-DAG: {{declare|define available_externally}} dllimport x86_thiscallcc void @_ZN34ExplicitlySpecializedClassTemplateIPvE1fEv
+
+//===----------------------------------------------------------------------===//
+// Classes with template base classes
+//===----------------------------------------------------------------------===//
+
+template <typename T> struct ClassTemplate { void func() {} };
+template <typename T> struct __declspec(dllexport) ExportedClassTemplate { void func() {} };
+template <typename T> struct __declspec(dllimport) ImportedClassTemplate { void func() {} };
+
+template <typename T> struct ExplicitlySpecializedTemplate { void func() {} };
+template <> struct ExplicitlySpecializedTemplate<int> { void func() {} };
+template <typename T> struct ExplicitlyExportSpecializedTemplate { void func() {} };
+template <> struct __declspec(dllexport) ExplicitlyExportSpecializedTemplate<int> { void func() {} };
+template <typename T> struct ExplicitlyImportSpecializedTemplate { void func() {} };
+template <> struct __declspec(dllimport) ExplicitlyImportSpecializedTemplate<int> { void func() {} };
+
+template <typename T> struct ExplicitlyInstantiatedTemplate { void func() {} };
+template struct ExplicitlyInstantiatedTemplate<int>;
+template <typename T> struct ExplicitlyExportInstantiatedTemplate { void func() {} };
+template struct __declspec(dllexport) ExplicitlyExportInstantiatedTemplate<int>;
+template <typename T> struct ExplicitlyImportInstantiatedTemplate { void func() {} };
+template struct __declspec(dllimport) ExplicitlyImportInstantiatedTemplate<int>;
+
+
+// MS: ClassTemplate<int> gets imported.
+struct __declspec(dllimport) DerivedFromTemplate : public ClassTemplate<int> {};
+USEMEMFUNC(ClassTemplate<int>, func)
+// M32-DAG: {{declare|define available_externally}} dllimport x86_thiscallcc void @"\01?func@?$ClassTemplate@H@@QAEXXZ"
+// G32-DAG: define linkonce_odr x86_thiscallcc void @_ZN13ClassTemplateIiE4funcEv
+
+// ImportedTemplate is explicitly imported.
+struct __declspec(dllimport) DerivedFromImportedTemplate : public ImportedClassTemplate<int> {};
+USEMEMFUNC(ImportedClassTemplate<int>, func)
+// M32-DAG: {{declare|define available_externally}} dllimport x86_thiscallcc void @"\01?func@?$ImportedClassTemplate@H@@QAEXXZ"
+// G32-DAG: declare dllimport x86_thiscallcc void @_ZN21ImportedClassTemplateIiE4funcEv
+
+// ExportedTemplate is explicitly exported.
+struct __declspec(dllimport) DerivedFromExportedTemplate : public ExportedClassTemplate<int> {};
+USEMEMFUNC(ExportedClassTemplate<int>, func)
+// M32-DAG: define weak_odr dllexport x86_thiscallcc void @"\01?func@?$ExportedClassTemplate@H@@QAEXXZ"
+// G32-DAG: define weak_odr dllexport x86_thiscallcc void @_ZN21ExportedClassTemplateIiE4funcEv
+
+// Base class already instantiated without attribute.
+struct DerivedFromTemplateD : public ClassTemplate<double> {};
+struct __declspec(dllimport) DerivedFromTemplateD2 : public ClassTemplate<double> {};
+USEMEMFUNC(ClassTemplate<double>, func)
+// M32-DAG: define linkonce_odr x86_thiscallcc void @"\01?func@?$ClassTemplate@N@@QAEXXZ"
+// G32-DAG: define linkonce_odr x86_thiscallcc void @_ZN13ClassTemplateIdE4funcEv
+
+// MS: Base class already instantiated with dfferent attribute.
+struct __declspec(dllexport) DerivedFromTemplateB : public ClassTemplate<bool> {};
+struct __declspec(dllimport) DerivedFromTemplateB2 : public ClassTemplate<bool> {};
+USEMEMFUNC(ClassTemplate<bool>, func)
+// M32-DAG: define weak_odr dllexport x86_thiscallcc void @"\01?func@?$ClassTemplate@_N@@QAEXXZ"
+// G32-DAG: define linkonce_odr x86_thiscallcc void @_ZN13ClassTemplateIbE4funcEv
+
+// Base class already specialized without dll attribute.
+struct __declspec(dllimport) DerivedFromExplicitlySpecializedTemplate : public ExplicitlySpecializedTemplate<int> {};
+USEMEMFUNC(ExplicitlySpecializedTemplate<int>, func)
+// M32-DAG: define linkonce_odr x86_thiscallcc void @"\01?func@?$ExplicitlySpecializedTemplate@H@@QAEXXZ"
+// G32-DAG: define linkonce_odr x86_thiscallcc void @_ZN29ExplicitlySpecializedTemplateIiE4funcEv
+
+// Base class alredy specialized with export attribute.
+struct __declspec(dllimport) DerivedFromExplicitlyExportSpecializedTemplate : public ExplicitlyExportSpecializedTemplate<int> {};
+USEMEMFUNC(ExplicitlyExportSpecializedTemplate<int>, func)
+// M32-DAG: define weak_odr dllexport x86_thiscallcc void @"\01?func@?$ExplicitlyExportSpecializedTemplate@H@@QAEXXZ"
+// G32-DAG: define weak_odr dllexport x86_thiscallcc void @_ZN35ExplicitlyExportSpecializedTemplateIiE4funcEv
+
+// Base class already specialized with import attribute.
+struct __declspec(dllimport) DerivedFromExplicitlyImportSpecializedTemplate : public ExplicitlyImportSpecializedTemplate<int> {};
+USEMEMFUNC(ExplicitlyImportSpecializedTemplate<int>, func)
+// M32-DAG: {{declare|define available_externally}} dllimport x86_thiscallcc void @"\01?func@?$ExplicitlyImportSpecializedTemplate@H@@QAEXXZ"
+// G32-DAG: {{declare|define available_externally}} dllimport x86_thiscallcc void @_ZN35ExplicitlyImportSpecializedTemplateIiE4funcEv
+
+// Base class already instantiated without dll attribute.
+struct __declspec(dllimport) DerivedFromExplicitlyInstantiatedTemplate : public ExplicitlyInstantiatedTemplate<int> {};
+USEMEMFUNC(ExplicitlyInstantiatedTemplate<int>, func)
+// M32-DAG: define weak_odr x86_thiscallcc void @"\01?func@?$ExplicitlyInstantiatedTemplate@H@@QAEXXZ"
+// G32-DAG: define weak_odr x86_thiscallcc void @_ZN30ExplicitlyInstantiatedTemplateIiE4funcEv
+
+// Base class already instantiated with export attribute.
+struct __declspec(dllimport) DerivedFromExplicitlyExportInstantiatedTemplate : public ExplicitlyExportInstantiatedTemplate<int> {};
+USEMEMFUNC(ExplicitlyExportInstantiatedTemplate<int>, func)
+// M32-DAG: define weak_odr dllexport x86_thiscallcc void @"\01?func@?$ExplicitlyExportInstantiatedTemplate@H@@QAEXXZ"
+// G32-DAG: define weak_odr dllexport x86_thiscallcc void @_ZN36ExplicitlyExportInstantiatedTemplateIiE4funcEv
+
+// Base class already instantiated with import attribute.
+struct __declspec(dllimport) DerivedFromExplicitlyImportInstantiatedTemplate : public ExplicitlyImportInstantiatedTemplate<int> {};
+USEMEMFUNC(ExplicitlyImportInstantiatedTemplate<int>, func)
+// M32-DAG: {{declare|define available_externally}} dllimport x86_thiscallcc void @"\01?func@?$ExplicitlyImportInstantiatedTemplate@H@@QAEXXZ"
+// G32-DAG: {{declare|define available_externally}} dllimport x86_thiscallcc void @_ZN36ExplicitlyImportInstantiatedTemplateIiE4funcEv
+
+// MS: A dll attribute propagates through multiple levels of instantiation.
+template <typename T> struct TopClass { void func() {} };
+template <typename T> struct MiddleClass : public TopClass<T> { };
+struct __declspec(dllimport) BottomClas : public MiddleClass<int> { };
+USEMEMFUNC(TopClass<int>, func)
+// M32-DAG: {{declare|define available_externally}} dllimport x86_thiscallcc void @"\01?func@?$TopClass@H@@QAEXXZ"
+// G32-DAG: define linkonce_odr x86_thiscallcc void @_ZN8TopClassIiE4funcEv