[libcxx] Remove unexpected handlers in C++17

[EricWF]

Summary

This patch implements P0003R5 which removes exception specifications from C++17.

The only changes to the library are removing set_unexpected, get_unexpected, unexpected, and unexpected_handler. These functions can be re-enabled in C++17 using _LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS.

@mclow.lists what do you think about removing stuff is this way?

[mclow.lists]

LGTM. Sorry for the slow response.

[EricWF]

• Update so that it merges with master.

• add _LIBCPP_ENABLE_CXX17_REMOVED_FEATURES macro for re-enabling all removed C++17 features.

docs/UsingLibcxx.rst

 
 **_LIBCPP_DISABLE_ADDITIONAL_DIAGNOSTICS**:
   This macro disables the additional diagnostics generated by libc++ using the
   `diagnose_if` attribute. These additional diagnostics include checks for:
 
     * Giving `set`, `map`, `multiset`, `multimap` a comparator which is not
       const callable.
 
+C++17 Specific Configuration Macros
+-----------------------------------
+**_LIBCPP_ENABLE_CXX17_REMOVED_FEATURES**:
+  This macro is used to re-enable all the features removed in C++17. The effect
+  is equivalent to manually defining each macro listed below.
+
+**_LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS**:
+  This macro is used to re-enable the `set_unexpected`, `get_unexpected`, and
+  `unexpected` functions, which were removed in C++17. Unless this macro is
+  define those names will not be available in C++17.

include/__config

 
 #if defined(_LIBCPP_ABI_MICROSOFT) && \
    (defined(_LIBCPP_COMPILER_MSVC) || __has_declspec_attribute(empty_bases))
 # define _LIBCPP_DECLSPEC_EMPTY_BASES __declspec(empty_bases)
 #else
 # define _LIBCPP_DECLSPEC_EMPTY_BASES
 #endif
 
+#if defined(_LIBCPP_ENABLE_CXX17_REMOVED_FEATURES)
+# define _LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS
+#endif // _LIBCPP_ENABLE_CXX17_REMOVED_FEATURES
+
 #endif // __cplusplus
 
 #endif // _LIBCPP_CONFIG

include/exception

 {
 public:
     _LIBCPP_INLINE_VISIBILITY bad_exception() _NOEXCEPT {}
     virtual ~bad_exception() _NOEXCEPT;
     virtual const char* what() const _NOEXCEPT;
 };
 #endif // !_LIBCPP_ABI_MICROSOFT
 
+#if _LIBCPP_STD_VER <= 14 \
+    || defined(_LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS) \
+    || defined(_LIBCPP_BUILDING_LIBRARY)
 typedef void (*unexpected_handler)();
 _LIBCPP_FUNC_VIS unexpected_handler set_unexpected(unexpected_handler) _NOEXCEPT;
 _LIBCPP_FUNC_VIS unexpected_handler get_unexpected() _NOEXCEPT;
 _LIBCPP_NORETURN _LIBCPP_FUNC_VIS void unexpected();
+#endif
 
 typedef void (*terminate_handler)();
 _LIBCPP_FUNC_VIS terminate_handler set_terminate(terminate_handler) _NOEXCEPT;
 _LIBCPP_FUNC_VIS terminate_handler get_terminate() _NOEXCEPT;
 _LIBCPP_NORETURN _LIBCPP_FUNC_VIS void terminate() _NOEXCEPT;
 
 _LIBCPP_FUNC_VIS bool uncaught_exception() _NOEXCEPT;
 _LIBCPP_FUNC_VIS int uncaught_exceptions() _NOEXCEPT;

test/libcxx/depr/enable_removed_cpp17_features.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// Test that defining _LIBCPP_ENABLE_CXX17_REMOVED_FEATURES correctly defines
+// _LIBCPP_ENABLE_CXX17_REMOVED_FOO for each individual component macro.
+
+// MODULES_DEFINES: _LIBCPP_ENABLE_CXX17_REMOVED_FEATURES
+#define _LIBCPP_ENABLE_CXX17_REMOVED_FEATURES
+#include <__config>
+
+#ifndef _LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS
+#error _LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS must be defined
+#endif
+
+int main() {
+}

test/libcxx/depr/exception.unexpected/get_unexpected.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// test get_unexpected
+
+
+// MODULES_DEFINES: _LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS
+#define _LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS
+#include <exception>
+#include <cassert>
+#include <cstdlib>
+
+void f1() {}
+void f2() {}
+
+void f3()
+{
+    std::exit(0);
+}
+
+int main()
+{
+
+    std::unexpected_handler old = std::get_unexpected();
+    // verify there is a previous unexpected handler
+    assert(old);
+    std::set_unexpected(f1);
+    assert(std::get_unexpected() == f1);
+    // verify f1 was replace with f2
+    std::set_unexpected(f2);
+    assert(std::get_unexpected() == f2);
+    // verify calling original unexpected handler calls terminate
+    std::set_terminate(f3);
+    (*old)();
+    assert(0);
+}

test/libcxx/depr/exception.unexpected/set_unexpected.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// test set_unexpected
+
+// MODULES_DEFINES: _LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS
+#define _LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS
+#include <exception>
+#include <cassert>
+#include <cstdlib>
+
+void f1() {}
+void f2() {}
+
+void f3()
+{
+    std::exit(0);
+}
+
+int main()
+{
+    std::unexpected_handler old = std::set_unexpected(f1);
+    // verify there is a previous unexpected handler
+    assert(old);
+    // verify f1 was replace with f2
+    assert(std::set_unexpected(f2) == f1);
+    // verify calling original unexpected handler calls terminate
+    std::set_terminate(f3);
+    (*old)();
+    assert(0);
+}

test/libcxx/depr/exception.unexpected/unexpected.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// test unexpected
+
+// MODULES_DEFINES: _LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS
+#define _LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS
+#include <exception>
+#include <cstdlib>
+#include <cassert>
+
+void fexit()
+{
+    std::exit(0);
+}
+
+int main()
+{
+    std::set_unexpected(fexit);
+    std::unexpected();
+    assert(false);
+}

test/libcxx/depr/exception.unexpected/unexpected_disabled_cpp17.fail.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// test unexpected
+
+#include <exception>
+
+void f() {}
+
+int main() {
+  using T = std::unexpected_handler; // expected-error {{no type named 'unexpected_handler' in namespace 'std'}}
+  std::unexpected(); // expected-error {{no member named 'unexpected' in namespace 'std'}}
+  std::get_unexpected(); // expected-error {{no member named 'get_unexpected' in namespace 'std'}}
+  std::set_unexpected(f); // expected-error {{no type named 'set_unexpected' in namespace 'std'}}
+}

test/std/depr/exception.unexpected/set.unexpected/get_unexpected.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is dual licensed under the MIT and the University of Illinois Open
 // Source Licenses. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
+// REQUIRES: c++98 || c++03 || c++11 || c++14
+
 // test get_unexpected
 
 #include <exception>
 #include <cassert>
 #include <cstdlib>
 
 void f1() {}
 void f2() {}

test/std/depr/exception.unexpected/set.unexpected/set_unexpected.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is dual licensed under the MIT and the University of Illinois Open
 // Source Licenses. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
+// REQUIRES: c++98 || c++03 || c++11 || c++14
+
 // test set_unexpected
 
 #include <exception>
 #include <cassert>
 #include <cstdlib>
 
 void f1() {}
 void f2() {}

test/std/depr/exception.unexpected/unexpected.handler/unexpected_handler.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is dual licensed under the MIT and the University of Illinois Open
 // Source Licenses. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
+// REQUIRES: c++98 || c++03 || c++11 || c++14
+
 // test unexpected_handler
 
 #include <exception>
 
 void f() {}
 
 int main()
 {
     std::unexpected_handler p = f;
     ((void)p);
 }

test/std/depr/exception.unexpected/unexpected/unexpected.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is dual licensed under the MIT and the University of Illinois Open
 // Source Licenses. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
+// REQUIRES: c++98 || c++03 || c++11 || c++14
+
 // test unexpected
 
 #include <exception>
 #include <cstdlib>
 #include <cassert>
 
 void f1()
 {

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