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4 Commits

Author SHA1 Message Date
Shoaib Meenai 190994e435 [libc++] Fix extern template visibility for Windows 
On Windows, marking an `extern template class` declaration as exported
actually forces an instantiation, which is not the desired behavior.
Instead, the actual explicit instantiations need to be exported.

Differential Revision: https://reviews.llvm.org/D24679

llvm-svn: 281925
 2016-09-19 18:29:07 +00:00
Eric Fiselier 991c354b01 Update _LIBCPP_EXCEPTION_ABI doc with @mclow's feedback 
llvm-svn: 281695
 2016-09-16 02:51:26 +00:00
Eric Fiselier f8f31c4985 [libc++] Add _LIBCPP_EXTERN_TEMPLATE_INLINE_VISIBILITY to support GCC ABI compatibility 
Summary:
GCC and Clang handle visibility attributes on the out-of-line definition of externally instantiated templates differently. For example in the reproducer below Clang will emit both 'foo' and 'bar' with default visibility while GCC only emits a non-hidden 'foo'.  

```
// RUN: g++ -std=c++11 -shared -O3 test.cpp && sym_extract.py a.out
// RUN: clang++ -std=c++11 -shared -O3 test.cpp && sym_extract.py a.out
#define INLINE_VISIBILITY __attribute__((visibility("hidden"), always_inline))

template <class T>
struct Foo {
  void foo();
  void bar();
};

template <class T>
void Foo<T>::foo() {}

template <class T>
inline INLINE_VISIBILITY
void Foo<T>::bar() {}

template struct Foo<int>;
```

This difference creates ABI incompatibilities between Clang and GCC built dylibs. Specifically GCC built dylibs lack definitions for various member functions of `basic_string`, `basic_istream`, `basic_ostream`, `basic_iostream`, and `basic_streambuf` (All of these types are externally instantiated). 

Surprisingly these missing symbols don't cause many problems because the functions are marked `always_inline`  therefore the dylib definition is rarely needed. However when an out-of-line definition is required then GCC built dylibs will fail to link. For example [GCC built dylibs cannot build Clang](http://stackoverflow.com/questions/39454262/clang-build-errors).

This patch works around this issue by adding `_LIBCPP_EXTERN_TEMPLATE_INLINE_VISIBILITY` which is used to mark externally instantiated member functions as always inline. When building the library `_LIBCPP_EXTERN_TEMPLATE_INLINE_VISIBILITY` sets the symbol's visibility to "default" instead of "hidden", otherwise it acts exactly the same as `_LIBCPP_INLINE_VISIBILITY`.

After applying this patch GCC dylibs now contain:
  * `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE7sungetcEv`
  * `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE5gbumpEi`
  * `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE7sungetcEv`
  * `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE9sputbackcEc`
  * `_ZNSt3__113basic_istreamIwNS_11char_traitsIwEEE3getERNS_15basic_streambufIwS2_EE`
  * `_ZNSt3__113basic_ostreamIwNS_11char_traitsIwEEElsEPFRNS_9basic_iosIwS2_EES6_E`
  * `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE4setpEPcS4_`
  * `_ZNSt3__113basic_ostreamIwNS_11char_traitsIwEEEC1EPNS_15basic_streambufIwS2_EE`
  * `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE6snextcEv`
  * `_ZNSt3__113basic_istreamIcNS_11char_traitsIcEEE4swapERS3_`
  * `_ZNSt3__113basic_istreamIwNS_11char_traitsIwEEE4swapERS3_`
  * `_ZNSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEE6__initEPKcm`
  * `_ZNSt3__113basic_istreamIcNS_11char_traitsIcEEErsEPFRNS_8ios_baseES5_E`
  * `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE9pubsetbufEPcl`
  * `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE10pubseekoffExNS_8ios_base7seekdirEj`
  * `_ZNSt3__113basic_istreamIwNS_11char_traitsIwEEErsEPFRNS_9basic_iosIwS2_EES6_E`
  * `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE5pbumpEi`
  * `_ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEE5seekpENS_4fposI11__mbstate_tEE`
  * `_ZNSt3__113basic_istreamIcNS_11char_traitsIcEEE7getlineEPcl`
  * `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE5sgetcEv`
  * `_ZNSt3__113basic_istreamIcNS_11char_traitsIcEEE3getERNS_15basic_streambufIcS2_EE`
  * `_ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEElsEPFRNS_8ios_baseES5_E`
  * `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE8in_availEv`
  * `_ZNSt3__113basic_istreamIwNS_11char_traitsIwEEErsEPFRNS_8ios_baseES5_E`
  * `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE6sbumpcEv`
  * `_ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEElsEPFRNS_9basic_iosIcS2_EES6_E`
  * `_ZNSt3__113basic_istreamIcNS_11char_traitsIcEEE3getERc`
  * `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE6snextcEv`
  * `_ZNSt3__112basic_stringIwNS_11char_traitsIwEENS_9allocatorIwEEE6__initEmw`
  * `_ZNSt3__113basic_istreamIwNS_11char_traitsIwEEE7getlineEPwl`
  * `_ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEE5tellpEv`
  * `_ZNSt3__113basic_istreamIwNS_11char_traitsIwEEE3getERw`
  * `_ZNSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEE6__initEmc`
  * `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE7pubsyncEv`
  * `_ZNSt3__113basic_istreamIcNS_11char_traitsIcEEE3getEPcl`
  * `_ZNSt3__113basic_istreamIcNS_11char_traitsIcEEEC2EPNS_15basic_streambufIcS2_EE`
  * `_ZNSt3__113basic_istreamIcNS_11char_traitsIcEEErsEPFRNS_9basic_iosIcS2_EES6_E`
  * `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE7pubsyncEv`
  * `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE5sputcEc`
  * `_ZNSt3__113basic_ostreamIwNS_11char_traitsIwEEE5seekpExNS_8ios_base7seekdirE`
  * `_ZNKSt3__115basic_streambufIcNS_11char_traitsIcEEE6getlocEv`
  * `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE5gbumpEi`
  * `_ZNSt3__114basic_iostreamIcNS_11char_traitsIcEEE4swapERS3_`
  * `_ZNSt3__113basic_ostreamIwNS_11char_traitsIwEEE5seekpENS_4fposI11__mbstate_tEE`
  * `_ZNSt3__113basic_ostreamIwNS_11char_traitsIwEEE5tellpEv`
  * `_ZNSt3__113basic_ostreamIwNS_11char_traitsIwEEElsEPFRS3_S4_E`
  * `_ZNSt3__113basic_istreamIwNS_11char_traitsIwEEE3getEPwl`
  * `_ZNSt3__113basic_istreamIwNS_11char_traitsIwEEEC2EPNS_15basic_streambufIwS2_EE`
  * `_ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEElsEPFRS3_S4_E`
  * `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE4setgEPcS4_S4_`
  * `_ZNSt3__112basic_stringIwNS_11char_traitsIwEENS_9allocatorIwEEE6__initEPKwmm`
  * `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE4setgEPwS4_S4_`
  * `_ZNSt3__113basic_istreamIwNS_11char_traitsIwEEEC1EPNS_15basic_streambufIwS2_EE`
  * `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE8pubimbueERKNS_6localeE`
  * `_ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEE4swapERS3_`
  * `_ZNSt3__113basic_ostreamIwNS_11char_traitsIwEEEC2EPNS_15basic_streambufIwS2_EE`
  * `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE10pubseekposENS_4fposI11__mbstate_tEEj`
  * `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE5pbumpEi`
  * `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE5sgetcEv`
  * `_ZNSt3__113basic_ostreamIwNS_11char_traitsIwEEE4swapERS3_`
  * `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE10pubseekposENS_4fposI11__mbstate_tEEj`
  * `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE5sputnEPKcl`
  * `_ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEE5seekpExNS_8ios_base7seekdirE`
  * `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE5sgetnEPwl`
  * `_ZNSt3__113basic_ostreamIwNS_11char_traitsIwEEElsEPFRNS_8ios_baseES5_E`
  * `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE4setpEPwS4_`
  * `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE5sgetnEPcl`
  * `_ZNKSt3__115basic_streambufIwNS_11char_traitsIwEEE6getlocEv`
  * `_ZNSt3__114basic_iostreamIcNS_11char_traitsIcEEEC2EPNS_15basic_streambufIcS2_EE`
  * `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE8pubimbueERKNS_6localeE`
  * `_ZNSt3__114basic_iostreamIcNS_11char_traitsIcEEEC1EPNS_15basic_streambufIcS2_EE`
  * `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE8in_availEv`
  * `_ZNSt3__113basic_istreamIcNS_11char_traitsIcEEEC1EPNS_15basic_streambufIcS2_EE`
  * `_ZNSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEE6__initEPKcmm`
  * `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE6sbumpcEv`
  * `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE10pubseekoffExNS_8ios_base7seekdirEj`
  * `_ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEEC2EPNS_15basic_streambufIcS2_EE`
  * `_ZNSt3__113basic_istreamIwNS_11char_traitsIwEEErsEPFRS3_S4_E`
  * `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE9sputbackcEw`
  * `_ZNSt3__112basic_stringIwNS_11char_traitsIwEENS_9allocatorIwEEE6__initEPKwm`
  * `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE5sputnEPKwl`
  * `_ZNSt3__113basic_istreamIcNS_11char_traitsIcEEErsEPFRS3_S4_E`
  * `_ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEEC1EPNS_15basic_streambufIcS2_EE`
  * `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE9pubsetbufEPwl`
  * `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE5sputcEw`


This patch has no effect on Clang based builds.



Reviewers: mclow.lists, eugenis, danalbert, jroelofs, EricWF

Subscribers: beanz, cfe-commits, mgorny

Differential Revision: https://reviews.llvm.org/D24600

llvm-svn: 281681
 2016-09-16 00:00:48 +00:00
Eric Fiselier 49e2967f27 [libc++] Fix and document visibility attributes for Clang, GCC and Windows. 
Summary:
This patch fixes a number of problems with the visibility macros across GCC (on Unix) and Windows (DLL import/export semantics). All of the visibility macros are now documented under `DesignDocs/VisibilityMacros.rst`. Now I'll no longer forget the subtleties of each!

This patch adds two new visibility macros:

* `_LIBCPP_ENUM_VIS` for controlling the typeinfo of enum types. Only Clang supports this.
* `_LIBCPP_EXTERN_TEMPLATE_TYPE_VIS` for redefining visibility on explicit instantiation declarations. Clang and Windows require this.

After applying this patch GCC only emits one -Wattribute warning opposed to 30+.


Reviewers: mclow.lists, EricWF

Subscribers: beanz, mgorny, cfe-commits

Differential Revision: https://reviews.llvm.org/D24602

llvm-svn: 281673
 2016-09-15 22:27:07 +00:00