mstorsjo created this revision.
mstorsjo added reviewers: rnk, hans, smeenai.
Herald added a project: clang.
An explicit template instantiation declaration used to let callers assume both
outer and nested classes instantiations were defined in a different translation
unit.
If the instantiation is marked dllexport, only the outer class is exported, but
the caller will try to reference the instantiation of both outer and inner
classes.
This makes MinGW mode match both MSVC and Windows Itanium, by having
instantations only cover the outer class, and locally emitting definitions of
the nested classes. Windows Itanium was changed to use this behavious in SVN
r300804.
This deviates from what GCC does, but should be safe (and only inflate the
object file size a bit, but MSVC and Windows Itanium modes do the same), and
fixes cases where inner classes aren't dllexported.
This fixes missing references in combination with dllexported/imported template
intantiations.
GCC suffers from the same issue, reported at [1], but the issue is still
unresolved there. The issue can probably be solved either by making dllexport
cover all nested classes as well, or this way (matching MSVC).
[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89087
Repository:
rC Clang
https://reviews.llvm.org/D61175
Files:
lib/Sema/SemaTemplateInstantiate.cpp
test/CodeGenCXX/mingw-template-dllexport.cpp
Index: test/CodeGenCXX/mingw-template-dllexport.cpp
===================================================================
--- test/CodeGenCXX/mingw-template-dllexport.cpp
+++ test/CodeGenCXX/mingw-template-dllexport.cpp
@@ -1,5 +1,10 @@
// RUN: %clang_cc1 -emit-llvm -triple i686-mingw32 %s -o - | FileCheck %s
+#define JOIN2(x, y) x##y
+#define JOIN(x, y) JOIN2(x, y)
+#define UNIQ(name) JOIN(name, __LINE__)
+#define USEMEMFUNC(class, func) void (class::*UNIQ(use)())() { return
&class::func; }
+
template <class T>
class c {
void f();
@@ -36,3 +41,10 @@
// CHECK: define {{.*}} dllexport {{.*}} @_ZN5outerIiE1fEv
// CHECK-NOT: define {{.*}} dllexport {{.*}} @_ZN5outerIiE5inner1fEv
+
+extern template class __declspec(dllimport) outer<char>;
+USEMEMFUNC(outer<char>, f)
+USEMEMFUNC(outer<char>::inner, f)
+
+// CHECK: declare dllimport {{.*}} @_ZN5outerIcE1fEv
+// CHECK: define {{.*}} @_ZN5outerIcE5inner1fEv
Index: lib/Sema/SemaTemplateInstantiate.cpp
===================================================================
--- lib/Sema/SemaTemplateInstantiate.cpp
+++ lib/Sema/SemaTemplateInstantiate.cpp
@@ -2681,10 +2681,14 @@
continue;
if ((Context.getTargetInfo().getCXXABI().isMicrosoft() ||
- Context.getTargetInfo().getTriple().isWindowsItaniumEnvironment())
&&
+ Context.getTargetInfo().getTriple().isWindowsItaniumEnvironment() ||
+ Context.getTargetInfo().getTriple().isWindowsGNUEnvironment()) &&
TSK == TSK_ExplicitInstantiationDeclaration) {
// In MSVC and Windows Itanium mode, explicit instantiation decl of the
// outer class doesn't affect the inner class.
+ // In GNU mode, inner classes aren't dllexported. Don't let the
+ // instantiation cover the inner class, to avoid undefined references
+ // to inner classes that weren't exported.
continue;
}
Index: test/CodeGenCXX/mingw-template-dllexport.cpp
===================================================================
--- test/CodeGenCXX/mingw-template-dllexport.cpp
+++ test/CodeGenCXX/mingw-template-dllexport.cpp
@@ -1,5 +1,10 @@
// RUN: %clang_cc1 -emit-llvm -triple i686-mingw32 %s -o - | FileCheck %s
+#define JOIN2(x, y) x##y
+#define JOIN(x, y) JOIN2(x, y)
+#define UNIQ(name) JOIN(name, __LINE__)
+#define USEMEMFUNC(class, func) void (class::*UNIQ(use)())() { return &class::func; }
+
template <class T>
class c {
void f();
@@ -36,3 +41,10 @@
// CHECK: define {{.*}} dllexport {{.*}} @_ZN5outerIiE1fEv
// CHECK-NOT: define {{.*}} dllexport {{.*}} @_ZN5outerIiE5inner1fEv
+
+extern template class __declspec(dllimport) outer<char>;
+USEMEMFUNC(outer<char>, f)
+USEMEMFUNC(outer<char>::inner, f)
+
+// CHECK: declare dllimport {{.*}} @_ZN5outerIcE1fEv
+// CHECK: define {{.*}} @_ZN5outerIcE5inner1fEv
Index: lib/Sema/SemaTemplateInstantiate.cpp
===================================================================
--- lib/Sema/SemaTemplateInstantiate.cpp
+++ lib/Sema/SemaTemplateInstantiate.cpp
@@ -2681,10 +2681,14 @@
continue;
if ((Context.getTargetInfo().getCXXABI().isMicrosoft() ||
- Context.getTargetInfo().getTriple().isWindowsItaniumEnvironment()) &&
+ Context.getTargetInfo().getTriple().isWindowsItaniumEnvironment() ||
+ Context.getTargetInfo().getTriple().isWindowsGNUEnvironment()) &&
TSK == TSK_ExplicitInstantiationDeclaration) {
// In MSVC and Windows Itanium mode, explicit instantiation decl of the
// outer class doesn't affect the inner class.
+ // In GNU mode, inner classes aren't dllexported. Don't let the
+ // instantiation cover the inner class, to avoid undefined references
+ // to inner classes that weren't exported.
continue;
}
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