[v3 PATCH] LWG 2510, make the default constructors of library tag types explicit.

[v3 PATCH] LWG 2510, make the default constructors of library tag types explicit.

[Ville Voutilainen]

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Tested on Linux-X64.

2015-11-10  Ville Voutilainen  <ville.voutilainen@gmail.com>

    LWG 2510, make the default constructors of library tag types
    explicit.
    * include/bits/mutex.h (defer_lock_t, try_lock_t,
    adopt_lock_t): Add an explicit default constructor.
    * include/bits/stl_pair.h (piecewise_construct_t): Likewise.
    * include/bits/uses_allocator.h (allocator_arg_t): Likewise.
    * libsupc++/new (nothrow_t): Likewise.
    * testsuite/17_intro/tag_type_explicit_ctor.cc: New.

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diff --git a/libstdc++-v3/include/bits/mutex.h b/libstdc++-v3/include/bits/mutex.h
index 43f5b0b..dd27989 100644
--- a/libstdc++-v3/include/bits/mutex.h
+++ b/libstdc++-v3/include/bits/mutex.h
@@ -129,14 +129,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 #endif // _GLIBCXX_HAS_GTHREADS
 
   /// Do not acquire ownership of the mutex.
-  struct defer_lock_t { };
+  struct defer_lock_t { explicit defer_lock_t() = default; };
 
   /// Try to acquire ownership of the mutex without blocking.
-  struct try_to_lock_t { };
+  struct try_to_lock_t { explicit try_to_lock_t() = default; };
 
   /// Assume the calling thread has already obtained mutex ownership
   /// and manage it.
-  struct adopt_lock_t { };
+  struct adopt_lock_t { explicit adopt_lock_t() = default; };
 
   constexpr defer_lock_t	defer_lock { };
   constexpr try_to_lock_t	try_to_lock { };
diff --git a/libstdc++-v3/include/bits/stl_pair.h b/libstdc++-v3/include/bits/stl_pair.h
index dfcd357..d6f6b86 100644
--- a/libstdc++-v3/include/bits/stl_pair.h
+++ b/libstdc++-v3/include/bits/stl_pair.h
@@ -73,7 +73,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
 #if __cplusplus >= 201103L
   /// piecewise_construct_t
-  struct piecewise_construct_t { };
+  struct piecewise_construct_t { explicit piecewise_construct_t() = default; };
 
   /// piecewise_construct
   constexpr piecewise_construct_t piecewise_construct = piecewise_construct_t();
diff --git a/libstdc++-v3/include/bits/uses_allocator.h b/libstdc++-v3/include/bits/uses_allocator.h
index f9ea7d6..a0f084d 100644
--- a/libstdc++-v3/include/bits/uses_allocator.h
+++ b/libstdc++-v3/include/bits/uses_allocator.h
@@ -36,7 +36,7 @@ namespace std _GLIBCXX_VISIBILITY(default)
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
   /// [allocator.tag]
-  struct allocator_arg_t { };
+  struct allocator_arg_t { explicit allocator_arg_t() = default; };
 
   constexpr allocator_arg_t allocator_arg = allocator_arg_t();
 
diff --git a/libstdc++-v3/libsupc++/new b/libstdc++-v3/libsupc++/new
index 0f6a05a..8621f73 100644
--- a/libstdc++-v3/libsupc++/new
+++ b/libstdc++-v3/libsupc++/new
@@ -79,7 +79,12 @@ namespace std
   };
 #endif
 
-  struct nothrow_t { };
+  struct nothrow_t
+  {
+#if __cplusplus >= 201103L
+    explicit nothrow_t() = default;
+#endif
+  };
 
   extern const nothrow_t nothrow;
 
diff --git a/libstdc++-v3/testsuite/17_intro/tag_type_explicit_ctor.cc b/libstdc++-v3/testsuite/17_intro/tag_type_explicit_ctor.cc
new file mode 100644
index 0000000..4b9d217
--- /dev/null
+++ b/libstdc++-v3/testsuite/17_intro/tag_type_explicit_ctor.cc
@@ -0,0 +1,60 @@
+// { dg-do compile }
+// { dg-options "-std=gnu++11" }
+
+// Copyright (C) 2015 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+#include <new>
+#include <utility>
+#include <memory>
+#include <mutex>
+
+void f1(std::nothrow_t);
+void f2(std::piecewise_construct_t);
+void f3(std::allocator_arg_t);
+void f4(std::defer_lock_t);
+void f5(std::try_to_lock_t);
+void f6(std::adopt_lock_t);
+
+
+int main()
+{
+  std::nothrow_t v1;
+  std::piecewise_construct_t v2;
+  std::allocator_arg_t v3;
+  std::defer_lock_t v4;
+  std::try_to_lock_t v5;
+  std::try_to_lock_t v6;
+  std::nothrow_t v7 = {}; // { dg-error "explicit" }
+  std::piecewise_construct_t v8 = {}; // { dg-error "explicit" }
+  std::allocator_arg_t v9 = {}; // { dg-error "explicit" }
+  std::defer_lock_t v10 = {}; // { dg-error "explicit" }
+  std::try_to_lock_t v11 = {}; // { dg-error "explicit" }
+  std::try_to_lock_t v12 = {}; // { dg-error "explicit" }
+  f1(std::nothrow_t{});
+  f2(std::piecewise_construct_t{});
+  f3(std::allocator_arg_t{});
+  f4(std::defer_lock_t{});
+  f5(std::try_to_lock_t{});
+  f6(std::adopt_lock_t{});
+  f1({}); // { dg-error "explicit" }
+  f2({}); // { dg-error "explicit" }
+  f3({}); // { dg-error "explicit" }
+  f4({}); // { dg-error "explicit" }
+  f5({}); // { dg-error "explicit" }
+  f6({}); // { dg-error "explicit" }
+}

Re: [v3 PATCH] LWG 2510, make the default constructors of library tag types explicit.

[Jonathan Wakely]

On 10/11/15 22:01 +0200, Ville Voutilainen wrote:
>    LWG 2510, make the default constructors of library tag types
>    explicit.
>    * include/bits/mutex.h (defer_lock_t, try_lock_t,
>    adopt_lock_t): Add an explicit default constructor.
>    * include/bits/stl_pair.h (piecewise_construct_t): Likewise.
>    * include/bits/uses_allocator.h (allocator_arg_t): Likewise.
>    * libsupc++/new (nothrow_t): Likewise.
>    * testsuite/17_intro/tag_type_explicit_ctor.cc: New.

OK for trunk, thanks.

Re: [v3 PATCH] LWG 2510, make the default constructors of library tag types explicit.

[Gerald Pfeifer]

On Thu, 12 Nov 2015, Ville Voutilainen wrote:
> Note that that's a separate problem that has nothing to do with the
> tag-type-explicit-default-ctor patch.

On Thu, 12 Nov 2015, Jonathan Wakely wrote:
> Different issue.

Sorry, I had two different libstdc++ bootstrap failures in the
last 24 hours, and misassociated this one.

> Does adding #include <errno.h> to libstdc++-v3/include/std/thread
> solve it?

Yep, that worked.

On Thu, 12 Nov 2015, Jonathan Wakely wrote:
> Committed to trunk.

Thanks!

Gerald

Re: [v3 PATCH] LWG 2510, make the default constructors of library tag types explicit.

[Jonathan Wakely]

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On 12/11/15 14:36 +0000, Jonathan Wakely wrote:
>On 12/11/15 15:23 +0100, Gerald Pfeifer wrote:
>>On Wed, 11 Nov 2015, Jonathan Wakely wrote:
>>>Fixed by this patch.
>>
>>Thanks, Jonathan!  Unfortunately bootstrap is still broken
>>(on i386-unknown-freebsd11.0 at least):
>
>Different issue.
>
>>In file included from 
>>/scratch/tmp/gerald/gcc-HEAD/libstdc++-v3/src/c++11/thread.cc:27:0:
>>/scratch/tmp/gerald/OBJ-1112-1414/i386-unknown-freebsd10.2/libstdc++-v3/include/
>>thread: In function ‘void std::this_thread::sleep_for(const std::chrono::duration<_Rep1, _Period1>&)’:
>>/scratch/tmp/gerald/OBJ-1112-1414/i386-unknown-freebsd10.2/libstdc++-v3/include/
>>thread:300:44: error: ‘errno’ was not declared in this scope
>>while (::nanosleep(&__ts, &__ts) == -1 && errno == EINTR)
>>                                          ^
>>/scratch/tmp/gerald/OBJ-1112-1414/i386-unknown-freebsd10.2/libstdc++-v3/include/
>>thread:300:53: error: ‘EINTR’ was not declared in this scope
>>while (::nanosleep(&__ts, &__ts) == -1 && errno == EINTR)
>
>Does adding #include <errno.h> to libstdc++-v3/include/std/thread
>solve it?

Committed to trunk.



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commit ede84363f2a4374b0d16ffda19fbcffdc44221c3
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Nov 12 15:21:24 2015 +0000

    	* include/std/thread: Include <cerrno> for EINTR.

diff --git a/libstdc++-v3/include/std/thread b/libstdc++-v3/include/std/thread
index 5940e6e..8c01feb 100644
--- a/libstdc++-v3/include/std/thread
+++ b/libstdc++-v3/include/std/thread
@@ -38,6 +38,7 @@
 #include <chrono>
 #include <functional>
 #include <memory>
+#include <cerrno>
 #include <bits/functexcept.h>
 #include <bits/functional_hash.h>
 #include <bits/gthr.h>

Re: [v3 PATCH] LWG 2510, make the default constructors of library tag types explicit.

[Jonathan Wakely]

On 12/11/15 15:23 +0100, Gerald Pfeifer wrote:
>On Wed, 11 Nov 2015, Jonathan Wakely wrote:
>>Fixed by this patch.
>
>Thanks, Jonathan!  Unfortunately bootstrap is still broken
>(on i386-unknown-freebsd11.0 at least):

Different issue.

>In file included from 
>/scratch/tmp/gerald/gcc-HEAD/libstdc++-v3/src/c++11/thread.cc:27:0:
>/scratch/tmp/gerald/OBJ-1112-1414/i386-unknown-freebsd10.2/libstdc++-v3/include/
>thread: In function ‘void std::this_thread::sleep_for(const std::chrono::duration<_Rep1, _Period1>&)’:
>/scratch/tmp/gerald/OBJ-1112-1414/i386-unknown-freebsd10.2/libstdc++-v3/include/
>thread:300:44: error: ‘errno’ was not declared in this scope
> while (::nanosleep(&__ts, &__ts) == -1 && errno == EINTR)
>                                           ^
>/scratch/tmp/gerald/OBJ-1112-1414/i386-unknown-freebsd10.2/libstdc++-v3/include/
>thread:300:53: error: ‘EINTR’ was not declared in this scope
> while (::nanosleep(&__ts, &__ts) == -1 && errno == EINTR)

Does adding #include <errno.h> to libstdc++-v3/include/std/thread
solve it?

Re: [v3 PATCH] LWG 2510, make the default constructors of library tag types explicit.

[Ville Voutilainen]

On 12 November 2015 at 16:23, Gerald Pfeifer <gerald@pfeifer.com> wrote:
> On Wed, 11 Nov 2015, Jonathan Wakely wrote:
>>
>> Fixed by this patch.
>
>
> Thanks, Jonathan!  Unfortunately bootstrap is still broken
> (on i386-unknown-freebsd11.0 at least):
>
> In file included from
> /scratch/tmp/gerald/gcc-HEAD/libstdc++-v3/src/c++11/thread.cc:27:0:
> /scratch/tmp/gerald/OBJ-1112-1414/i386-unknown-freebsd10.2/libstdc++-v3/include/
> thread: In function ‘void std::this_thread::sleep_for(const
> std::chrono::duration<_Rep1, _Period1>&)’:
> /scratch/tmp/gerald/OBJ-1112-1414/i386-unknown-freebsd10.2/libstdc++-v3/include/
> thread:300:44: error: ‘errno’ was not declared in this scope
>  while (::nanosleep(&__ts, &__ts) == -1 && errno == EINTR)
>                                            ^
> /scratch/tmp/gerald/OBJ-1112-1414/i386-unknown-freebsd10.2/libstdc++-v3/include/
> thread:300:53: error: ‘EINTR’ was not declared in this scope
>  while (::nanosleep(&__ts, &__ts) == -1 && errno == EINTR)


Note that that's a separate problem that has nothing to do with the
tag-type-explicit-default-ctor
patch.

Re: [v3 PATCH] LWG 2510, make the default constructors of library tag types explicit.

[Gerald Pfeifer]

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On Wed, 11 Nov 2015, Jonathan Wakely wrote:
> Fixed by this patch.

Thanks, Jonathan!  Unfortunately bootstrap is still broken
(on i386-unknown-freebsd11.0 at least):

In file included from 
/scratch/tmp/gerald/gcc-HEAD/libstdc++-v3/src/c++11/thread.cc:27:0:
/scratch/tmp/gerald/OBJ-1112-1414/i386-unknown-freebsd10.2/libstdc++-v3/include/
thread: In function ‘void std::this_thread::sleep_for(const std::chrono::duration<_Rep1, _Period1>&)’:
/scratch/tmp/gerald/OBJ-1112-1414/i386-unknown-freebsd10.2/libstdc++-v3/include/
thread:300:44: error: ‘errno’ was not declared in this scope
  while (::nanosleep(&__ts, &__ts) == -1 && errno == EINTR)
                                            ^
/scratch/tmp/gerald/OBJ-1112-1414/i386-unknown-freebsd10.2/libstdc++-v3/include/
thread:300:53: error: ‘EINTR’ was not declared in this scope
  while (::nanosleep(&__ts, &__ts) == -1 && errno == EINTR)

Gerald

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commit 97c2da9d4cc11bd5dae077ccb5fda4e72f7c34d5
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Wed Nov 11 17:27:23 2015 +0000

    	* libsupc++/new_handler.cc: Fix for explicit constructor change.

diff --git a/libstdc++-v3/libsupc++/new_handler.cc b/libstdc++-v3/libsupc++/new_handler.cc
index a09012c..4da48b3 100644
--- a/libstdc++-v3/libsupc++/new_handler.cc
+++ b/libstdc++-v3/libsupc++/new_handler.cc
@@ -34,7 +34,7 @@ namespace
 }
 #endif
 
-const std::nothrow_t std::nothrow = { };
+const std::nothrow_t std::nothrow = std::nothrow_t{ };
 
 using std::new_handler;
 namespace

Re: [v3 PATCH] LWG 2510, make the default constructors of library tag types explicit.

[Jonathan Wakely]

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On 11/11/15 18:17 +0100, Dominique d'Humières wrote:
>Revision r230175
>
>> 2015-11-10  Ville Voutilainen  <ville.voutilainen@gmail.com>
>>
>>     LWG 2510, make the default constructors of library tag types
>>     explicit.
>>     * include/bits/mutex.h (defer_lock_t, try_lock_t,
>>     adopt_lock_t): Add an explicit default constructor.
>>     * include/bits/stl_pair.h (piecewise_construct_t): Likewise.
>>     * include/bits/uses_allocator.h (allocator_arg_t): Likewise.
>>     * libsupc++/new (nothrow_t): Likewise.
>>     * testsuite/17_intro/tag_type_explicit_ctor.cc: New.
>
> breaks bootstrap
>
>libtool: compile:  /opt/gcc/build_w/./gcc/xgcc -shared-libgcc -B/opt/gcc/build_w/./gcc -nostdinc++ -L/opt/gcc/build_w/x86_64-apple-darwin14.5.0/libstdc++-v3/src -L/opt/gcc/build_w/x86_64-apple-darwin14.5.0/libstdc++-v3/src/.libs -L/opt/gcc/build_w/x86_64-apple-darwin14.5.0/libstdc++-v3/libsupc++/.libs -B/opt/gcc/gcc6w/x86_64-apple-darwin14.5.0/bin/ -B/opt/gcc/gcc6w/x86_64-apple-darwin14.5.0/lib/ -isystem /opt/gcc/gcc6w/x86_64-apple-darwin14.5.0/include -isystem /opt/gcc/gcc6w/x86_64-apple-darwin14.5.0/sys-include -I/opt/gcc/work/libstdc++-v3/../libgcc -I/opt/gcc/build_w/x86_64-apple-darwin14.5.0/libstdc++-v3/include/x86_64-apple-darwin14.5.0 -I/opt/gcc/build_w/x86_64-apple-darwin14.5.0/libstdc++-v3/include -I/opt/gcc/work/libstdc++-v3/libsupc++ -D_GLIBCXX_SHARED -fno-implicit-templates -Wall -Wextra -Wwrite-strings -Wcast-qual -Wabi -fdiagnostics-show-location=once -fvisibility-inlines-hidden -ffunction-sections -fdata-sections -frandom-seed=new_handler.lo -g -O2 -std=gnu++11 -c ../../../../work/libstdc++-v3/libsupc++/new_handler.cc  -fno-common -DPIC -D_GLIBCXX_SHARED -o new_handler.o
>../../../../work/libstdc++-v3/libsupc++/new_handler.cc:37:39: error: converting to 'std::nothrow_t' from initializer list would use explicit constructor 'constexpr std::nothrow_t::nothrow_t()'
> const std::nothrow_t std::nothrow = { };
>                                       ^
>see https://gcc.gnu.org/ml/gcc-regression/2015-11/

Fixed by this patch.


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commit 97c2da9d4cc11bd5dae077ccb5fda4e72f7c34d5
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Wed Nov 11 17:27:23 2015 +0000

    	* libsupc++/new_handler.cc: Fix for explicit constructor change.

diff --git a/libstdc++-v3/libsupc++/new_handler.cc b/libstdc++-v3/libsupc++/new_handler.cc
index a09012c..4da48b3 100644
--- a/libstdc++-v3/libsupc++/new_handler.cc
+++ b/libstdc++-v3/libsupc++/new_handler.cc
@@ -34,7 +34,7 @@ namespace
 }
 #endif
 
-const std::nothrow_t std::nothrow = { };
+const std::nothrow_t std::nothrow = std::nothrow_t{ };
 
 using std::new_handler;
 namespace

Re: [v3 PATCH] LWG 2510, make the default constructors of library tag types explicit.

[Dominique d'Humières]

Revision r230175

> 2015-11-10  Ville Voutilainen  <ville.voutilainen@gmail.com>
>
>     LWG 2510, make the default constructors of library tag types
>     explicit.
>     * include/bits/mutex.h (defer_lock_t, try_lock_t,
>     adopt_lock_t): Add an explicit default constructor.
>     * include/bits/stl_pair.h (piecewise_construct_t): Likewise.
>     * include/bits/uses_allocator.h (allocator_arg_t): Likewise.
>     * libsupc++/new (nothrow_t): Likewise.
>     * testsuite/17_intro/tag_type_explicit_ctor.cc: New.

 breaks bootstrap

libtool: compile:  /opt/gcc/build_w/./gcc/xgcc -shared-libgcc -B/opt/gcc/build_w/./gcc -nostdinc++ -L/opt/gcc/build_w/x86_64-apple-darwin14.5.0/libstdc++-v3/src -L/opt/gcc/build_w/x86_64-apple-darwin14.5.0/libstdc++-v3/src/.libs -L/opt/gcc/build_w/x86_64-apple-darwin14.5.0/libstdc++-v3/libsupc++/.libs -B/opt/gcc/gcc6w/x86_64-apple-darwin14.5.0/bin/ -B/opt/gcc/gcc6w/x86_64-apple-darwin14.5.0/lib/ -isystem /opt/gcc/gcc6w/x86_64-apple-darwin14.5.0/include -isystem /opt/gcc/gcc6w/x86_64-apple-darwin14.5.0/sys-include -I/opt/gcc/work/libstdc++-v3/../libgcc -I/opt/gcc/build_w/x86_64-apple-darwin14.5.0/libstdc++-v3/include/x86_64-apple-darwin14.5.0 -I/opt/gcc/build_w/x86_64-apple-darwin14.5.0/libstdc++-v3/include -I/opt/gcc/work/libstdc++-v3/libsupc++ -D_GLIBCXX_SHARED -fno-implicit-templates -Wall -Wextra -Wwrite-strings -Wcast-qual -Wabi -fdiagnostics-show-location=once -fvisibility-inlines-hidden -ffunction-sections -fdata-sections -frandom-seed=new_handler.lo -g -O2 -std=gnu++11 -c ../../../../work/libstdc++-v3/libsupc++/new_handler.cc  -fno-common -DPIC -D_GLIBCXX_SHARED -o new_handler.o
../../../../work/libstdc++-v3/libsupc++/new_handler.cc:37:39: error: converting to 'std::nothrow_t' from initializer list would use explicit constructor 'constexpr std::nothrow_t::nothrow_t()'
 const std::nothrow_t std::nothrow = { };
                                       ^
see https://gcc.gnu.org/ml/gcc-regression/2015-11/

Dominique