[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
Sat May 17 00:30:08 PDT 2025
https://github.com/kikairoya updated https://github.com/llvm/llvm-project/pull/140145
>From 4f0eab77111d15515082c82d288f25ca88424a9e Mon Sep 17 00:00:00 2001
From: kikairoya <kikairoya at gmail.com>
Date: Mon, 21 Apr 2025 23:30:13 +0900
Subject: [PATCH 1/2] [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 92a3b90dbc4affe081eb5f6ebb8413d415ecc079 Mon Sep 17 00:00:00 2001
From: kikairoya <kikairoya at gmail.com>
Date: Sat, 17 May 2025 16:22:42 +0900
Subject: [PATCH 2/2] [libc++] std::ostream::sentry should excluded from
explicit instantiation on client-side
---
libcxx/docs/DesignDocs/VisibilityMacros.rst | 5 +++++
libcxx/include/__config | 8 ++++++++
libcxx/include/__ostream/basic_ostream.h | 2 +-
libcxx/include/istream | 2 +-
4 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/libcxx/docs/DesignDocs/VisibilityMacros.rst b/libcxx/docs/DesignDocs/VisibilityMacros.rst
index e9f88118b7ef3..b56ddf53dbfdc 100644
--- a/libcxx/docs/DesignDocs/VisibilityMacros.rst
+++ b/libcxx/docs/DesignDocs/VisibilityMacros.rst
@@ -93,6 +93,11 @@ Visibility Macros
the extern template declaration) as exported on Windows, as discussed above.
On all other platforms, this macro has an empty definition.
+**_LIBCPP_INNER_CLASS_IN_TEMPLATE_VIS**
+ To keep binary compatibility purpose only of a class not marked as `dllexport`
+ that is defined in a class template. Not to add this for new class, and this
+ can be replaced to `_LIBCPP_EXPORTED_FROM_ABI` at a timing of ABI change occurs.
+
Links
=====
diff --git a/libcxx/include/__config b/libcxx/include/__config
index 110450f6e9c51..91b75860c84ef 100644
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -365,6 +365,11 @@ typedef __char32_t char32_t;
# define _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS
# define _LIBCPP_OVERRIDABLE_FUNC_VIS
# define _LIBCPP_EXPORTED_FROM_ABI
+# if defined(_LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS) || !__has_attribute(exclude_from_explicit_instantiation)
+# define _LIBCPP_INNER_CLASS_IN_TEMPLATE_VIS
+# else
+# define _LIBCPP_INNER_CLASS_IN_TEMPLATE_VIS __attribute__((__exclude_from_explicit_instantiation__))
+# endif
# elif defined(_LIBCPP_BUILDING_LIBRARY)
# if defined(__MINGW32__)
# define _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS __declspec(dllexport)
@@ -375,11 +380,13 @@ typedef __char32_t char32_t;
# endif
# define _LIBCPP_OVERRIDABLE_FUNC_VIS __declspec(dllexport)
# define _LIBCPP_EXPORTED_FROM_ABI __declspec(dllexport)
+# define _LIBCPP_INNER_CLASS_IN_TEMPLATE_VIS
# else
# define _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS __declspec(dllimport)
# define _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS
# define _LIBCPP_OVERRIDABLE_FUNC_VIS
# define _LIBCPP_EXPORTED_FROM_ABI __declspec(dllimport)
+# define _LIBCPP_INNER_CLASS_IN_TEMPLATE_VIS
# endif
# define _LIBCPP_HIDDEN
@@ -399,6 +406,7 @@ typedef __char32_t char32_t;
# define _LIBCPP_EXPORTED_FROM_ABI _LIBCPP_VISIBILITY("default")
# define _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS _LIBCPP_VISIBILITY("default")
# define _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS
+# define _LIBCPP_INNER_CLASS_IN_TEMPLATE_VIS
// TODO: Make this a proper customization point or remove the option to override it.
# ifndef _LIBCPP_OVERRIDABLE_FUNC_VIS
diff --git a/libcxx/include/__ostream/basic_ostream.h b/libcxx/include/__ostream/basic_ostream.h
index f7473a36d8ccc..a72350501ccda 100644
--- a/libcxx/include/__ostream/basic_ostream.h
+++ b/libcxx/include/__ostream/basic_ostream.h
@@ -71,7 +71,7 @@ class basic_ostream : virtual public basic_ios<_CharT, _Traits> {
public:
// 27.7.2.4 Prefix/suffix:
- class sentry;
+ class _LIBCPP_INNER_CLASS_IN_TEMPLATE_VIS sentry;
// 27.7.2.6 Formatted output:
inline _LIBCPP_HIDE_FROM_ABI_AFTER_V1 basic_ostream& operator<<(basic_ostream& (*__pf)(basic_ostream&)) {
diff --git a/libcxx/include/istream b/libcxx/include/istream
index 95340c739c118..b41dd59060f78 100644
--- a/libcxx/include/istream
+++ b/libcxx/include/istream
@@ -228,7 +228,7 @@ public:
basic_istream& operator=(const basic_istream& __rhs) = delete;
// 27.7.1.1.3 Prefix/suffix:
- class sentry;
+ class _LIBCPP_INNER_CLASS_IN_TEMPLATE_VIS sentry;
// 27.7.1.2 Formatted input:
inline _LIBCPP_HIDE_FROM_ABI_AFTER_V1 basic_istream& operator>>(basic_istream& (*__pf)(basic_istream&)) {
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