[clang] [libcxx] [Cygwin][MinGW] Internal class in explicitly-instantiation-declarated template should be instantiated (PR #140145)
Tomohiro Kashiwada via cfe-commits
cfe-commits at lists.llvm.org
Fri May 16 05:06:45 PDT 2025
https://github.com/kikairoya updated https://github.com/llvm/llvm-project/pull/140145
>From 827e89b8148e7eaa69bbae342cfb2a59d1b09133 Mon Sep 17 00:00:00 2001
From: kikairoya <kikairoya at gmail.com>
Date: Mon, 21 Apr 2025 23:30:13 +0900
Subject: [PATCH 1/3] [Cygwin][MinGW] Internal class in
explicitly-instantiation-declarated template should be instantiated
In-code comment says "explicit instantiation decl of the outer class
doesn't affect the inner class" but this behavior seems MSVC
specific, MinGW-GCC and Cygwin-GCC does not.
Clang should honor gcc's behavior.
This change fixes std::string compatibilty and resolves strange link
error (statically linked), strange crash (dynamically linked) using
libstdc++ on Cygwin.
---
clang/lib/Sema/SemaTemplateInstantiate.cpp | 1 +
.../CodeGenCXX/mingw-template-dllexport.cpp | 109 +++++++++++++++---
2 files changed, 93 insertions(+), 17 deletions(-)
diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp
index d028eea4f8f3e..b7c27b3795f5d 100644
--- a/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -4247,6 +4247,7 @@ Sema::InstantiateClassMembers(SourceLocation PointOfInstantiation,
continue;
if (Context.getTargetInfo().getTriple().isOSWindows() &&
+ !Context.getTargetInfo().getTriple().isOSCygMing() &&
TSK == TSK_ExplicitInstantiationDeclaration) {
// On Windows, explicit instantiation decl of the outer class doesn't
// affect the inner class. Typically extern template declarations are
diff --git a/clang/test/CodeGenCXX/mingw-template-dllexport.cpp b/clang/test/CodeGenCXX/mingw-template-dllexport.cpp
index de112d6da53db..a6047b5955e96 100644
--- a/clang/test/CodeGenCXX/mingw-template-dllexport.cpp
+++ b/clang/test/CodeGenCXX/mingw-template-dllexport.cpp
@@ -6,46 +6,121 @@
#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; }
+#define USEMEMFUNC(class, func) auto UNIQ(use) = &class::func;
template <class T>
class c {
+ // MinGW-GCC does not apply 'dllexport' to inline member function in dll-exported template but clang does from long ago.
void f() {}
+ void g();
+ inline static int u = 0;
+ static int v;
};
+template <class T> void c<T>::g() {}
+template <class T> int c<T>::v = 0;
+// #1
template class __declspec(dllexport) c<int>;
-// CHECK: define {{.*}} dllexport {{.*}} @_ZN1cIiE1fEv
-
+// #2
extern template class __declspec(dllexport) c<char>;
template class c<char>;
-// CHECK: define {{.*}} dllexport {{.*}} @_ZN1cIcE1fEv
-
+// #3
extern template class c<double>;
-template class __declspec(dllexport) c<double>;
+template class __declspec(dllexport) c<double>; // expected-warning {{ 'dllexport' attribute ignored on explicit instantiation definition }}
-// CHECK-NOT: define {{.*}} dllexport {{.*}} @_ZN1cIdE1fEv
template <class T>
struct outer {
- void f();
+ void f() {}
+ void g();
+ inline static int u = 0;
+ static int v;
+ // MinGW-GCC and Clang does not apply 'dllexport' to inner type and its sub-elements in template class.
struct inner {
- void f();
+ void f() {}
+ void g();
+ inline static int u = 0;
+ static int v;
};
};
-template <class T> void outer<T>::f() {}
-template <class T> void outer<T>::inner::f() {}
+template <class T> void outer<T>::g() {}
+template <class T> void outer<T>::inner::g() {}
+template <class T> int outer<T>::v = 0;
+template <class T> int outer<T>::inner::v = 0;
-template class __declspec(dllexport) outer<int>;
+// #4
+template struct __declspec(dllexport) outer<int>;
-// CHECK: define {{.*}} dllexport {{.*}} @_ZN5outerIiE1fEv
-// CHECK-NOT: define {{.*}} dllexport {{.*}} @_ZN5outerIiE5inner1fEv
-
-extern template class __declspec(dllimport) outer<char>;
+// #5
+extern template struct __declspec(dllimport) outer<char>;
USEMEMFUNC(outer<char>, f)
+USEMEMFUNC(outer<char>, g)
+USEMEMFUNC(outer<char>, u)
+USEMEMFUNC(outer<char>, v)
USEMEMFUNC(outer<char>::inner, f)
+USEMEMFUNC(outer<char>::inner, g)
+USEMEMFUNC(outer<char>::inner, u)
+USEMEMFUNC(outer<char>::inner, v)
+
+
+// #1 variables
+// CHECK: @_ZN1cIiE1uE = {{.*}} dllexport {{.*}}
+// CHECK: @_ZN1cIiE1vE = {{.*}} dllexport {{.*}}
+
+// #2 variables
+// CHECK: @_ZN1cIcE1uE = {{.*}} dllexport {{.*}}
+// CHECK: @_ZN1cIcE1vE = {{.*}} dllexport {{.*}}
+
+// #3 variables
+// CHECK: @_ZN1cIdE1uE = {{.*}}
+// CHECK-NOT: @_ZN1cIcE1uE = {{.*}} dllexport {{.*}}
+// CHECK: @_ZN1cIdE1vE = {{.*}}
+// CHECK-NOT: @_ZN1cIcE1vE = {{.*}} dllexport {{.*}}
+
+// #4 variables
+// CHECK: @_ZN5outerIiE1uE = {{.*}} dllexport {{.*}}
+// CHECK: @_ZN5outerIiE1vE = {{.*}} dllexport {{.*}}
+// CHECK: @_ZN5outerIiE5inner1uE = {{.*}}
+// CHECK-NOT: @_ZN5outerIiE5inner1uE = {{.*}} dllexport {{.*}}
+// CHECK: @_ZN5outerIiE5inner1vE = {{.*}}
+// CHECK-NOT: @_ZN5outerIiE5inner1vE = {{.*}} dllexport {{.*}}
+
+// #5 variables
+// CHECK: @_ZN5outerIcE1uE = external dllimport {{.*}}
+// CHECK: @_ZN5outerIcE1vE = external dllimport {{.*}}
+// CHECK-NOT: @_ZN5outerIcE5inner1uE = dllimport {{.*}}
+// CHECK-NOT: @_ZN5outerIcE5inner1vE = dllimport {{.*}}
+// CHECK: @_ZN5outerIcE5inner1uE = external {{.*}}
+// CHECK: @_ZN5outerIcE5inner1vE = external {{.*}}
+
+
+// #1 functions
+// CHECK: define {{.*}} dllexport {{.*}} @_ZN1cIiE1fEv
+// CHECK: define {{.*}} dllexport {{.*}} @_ZN1cIiE1gEv
+
+// #2 functions
+// CHECK: define {{.*}} dllexport {{.*}} @_ZN1cIcE1fEv
+// CHECK: define {{.*}} dllexport {{.*}} @_ZN1cIcE1gEv
+
+// #3 functions
+// CHECK-NOT: define {{.*}} dllexport {{.*}} @_ZN1cIdE1fEv
+// CHECK-NOT: define {{.*}} dllexport {{.*}} @_ZN1cIdE1gEv
+
+// #4 functions
+// CHECK: define {{.*}} dllexport {{.*}} @_ZN5outerIiE1fEv
+// CHECK: define {{.*}} dllexport {{.*}} @_ZN5outerIiE1gEv
+// CHECK-NOT: define {{.*}} dllexport {{.*}} @_ZN5outerIiE5inner1fEv
+// CHECK-NOT: define {{.*}} dllexport {{.*}} @_ZN5outerIiE5inner1gEv
+// #5 functions
// CHECK: declare dllimport {{.*}} @_ZN5outerIcE1fEv
-// CHECK: define {{.*}} @_ZN5outerIcE5inner1fEv
+// CHECK: declare dllimport {{.*}} @_ZN5outerIcE1gEv
+// CHECK-NOT: declare dllimport {{.*}} @_ZN5outerIcE5inner1fEv
+// CHECK-NOT: declare dllimport {{.*}} @_ZN5outerIcE5inner1gEv
+// CHECK-NOT: define {{.*}} @_ZN5outerIcE1fEv
+// CHECK-NOT: define {{.*}} @_ZN5outerIcE5inner1fEv
+// CHECK-NOT: define {{.*}} @_ZN5outerIcE1gEv
+// CHECK-NOT: define {{.*}} @_ZN5outerIcE5inner1gEv
>From c7a881a19ae3583840e54a415f8c31e8d7f6551b Mon Sep 17 00:00:00 2001
From: kikairoya <kikairoya at gmail.com>
Date: Fri, 16 May 2025 19:17:09 +0900
Subject: [PATCH 2/3] [LIBCXX] std::ostream::sentry should be exported
for testing by CI.
std::istream::sentry is left original to ensure test detects this defect.
---
libcxx/include/__ostream/basic_ostream.h | 4 ++++
libcxx/src/ios.instantiations.cpp | 8 ++++++++
2 files changed, 12 insertions(+)
diff --git a/libcxx/include/__ostream/basic_ostream.h b/libcxx/include/__ostream/basic_ostream.h
index f7473a36d8ccc..57f1941d1c6e3 100644
--- a/libcxx/include/__ostream/basic_ostream.h
+++ b/libcxx/include/__ostream/basic_ostream.h
@@ -665,8 +665,12 @@ basic_ostream<char, _Traits>& operator<<(basic_ostream<char, _Traits>&, const ch
# endif // _LIBCPP_STD_VER >= 20
+extern template _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_ostream<char>::sentry::sentry(basic_ostream<char>& __os);
+extern template _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_ostream<char>::sentry::~sentry();
extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_ostream<char>;
# if _LIBCPP_HAS_WIDE_CHARACTERS
+extern template _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_ostream<wchar_t>::sentry::sentry(basic_ostream<wchar_t>& __os);
+extern template _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_ostream<wchar_t>::sentry::~sentry();
extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_ostream<wchar_t>;
# endif
diff --git a/libcxx/src/ios.instantiations.cpp b/libcxx/src/ios.instantiations.cpp
index a8d267f7cfd42..230eb58920dd9 100644
--- a/libcxx/src/ios.instantiations.cpp
+++ b/libcxx/src/ios.instantiations.cpp
@@ -20,6 +20,10 @@ _LIBCPP_BEGIN_NAMESPACE_STD
template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ios<char>;
template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_streambuf<char>;
template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_istream<char>;
+#ifdef _MSC_VER
+template _LIBCPP_EXPORTED_FROM_ABI basic_ostream<char>::sentry::sentry(basic_ostream<char>& __os);
+template _LIBCPP_EXPORTED_FROM_ABI basic_ostream<char>::sentry::~sentry();
+#endif
template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ostream<char>;
template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_iostream<char>;
@@ -27,6 +31,10 @@ template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_iostream<char>;
template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ios<wchar_t>;
template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_streambuf<wchar_t>;
template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_istream<wchar_t>;
+# ifdef _MSC_VER
+template _LIBCPP_EXPORTED_FROM_ABI basic_ostream<wchar_t>::sentry::sentry(basic_ostream<wchar_t>& __os);
+template _LIBCPP_EXPORTED_FROM_ABI basic_ostream<wchar_t>::sentry::~sentry();
+# endif
template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ostream<wchar_t>;
#endif
>From 120ab9563260fe23317c50965055ee31e4ea1168 Mon Sep 17 00:00:00 2001
From: kikairoya <kikairoya at gmail.com>
Date: Fri, 16 May 2025 21:04:32 +0900
Subject: [PATCH 3/3] temporary disable wrong warning
---
clang/lib/Sema/SemaTemplate.cpp | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 14f9d1d03c5ed..cc3492b5b614e 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -9141,10 +9141,10 @@ Sema::CheckSpecializationInstantiationRedecl(SourceLocation NewLoc,
// in a program,
// MSVCCompat: MSVC silently ignores duplicate explicit instantiations.
- Diag(NewLoc, (getLangOpts().MSVCCompat)
- ? diag::ext_explicit_instantiation_duplicate
- : diag::err_explicit_instantiation_duplicate)
- << PrevDecl;
+ // Diag(NewLoc, (getLangOpts().MSVCCompat)
+ // ? diag::ext_explicit_instantiation_duplicate
+ // : diag::err_explicit_instantiation_duplicate)
+ // << PrevDecl;
Diag(DiagLocForExplicitInstantiation(PrevDecl, PrevPointOfInstantiation),
diag::note_previous_explicit_instantiation);
HasNoEffect = true;
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