binutils-gdb/gdbsupport/scoped_fd.h
Tom Tromey 0fa7617d84 Mark move constructors as "noexcept"
I recently learned that move constructors generally should be marked
"noexcept".  This ensures that standard containers will move objects
when possible, rather than copy them.

This patch fixes the cases I could find.  Note that implicitly-defined
or defaulted move constructors will automatically do what you'd
expect; that is, they are noexcept if all the members have noexcept
move constructors.

While doing this, I noticed a couple of odd cases where the move
constructor seemed to assume that the object being constructed could
have state requiring destruction.  I've fixed these as well.  See
completion_result and scoped_mmap.

gdb/ChangeLog
2020-04-20  Tom Tromey  <tromey@adacore.com>

	* python/python.c (struct gdbpy_event): Mark move constructor as
	noexcept.
	* python/py-tui.c (class gdbpy_tui_window_maker): Mark move
	constructor as noexcept.
	* completer.h (struct completion_result): Mark move constructor as
	noexcept.
	* completer.c (completion_result::completion_result): Use
	initialization style.  Don't call reset_match_list.

gdbsupport/ChangeLog
2020-04-20  Tom Tromey  <tromey@adacore.com>

	* scoped_mmap.h (scoped_mmap): Mark move constructor as noexcept.
	Use initialization style.  Don't call destroy.
	* scoped_fd.h (class scoped_fd): Mark move constructor as
	noexcept.
	* gdb_ref_ptr.h (class ref_ptr): Mark move constructor as
	noexcept.
2020-04-20 11:45:06 -06:00

88 lines
2.0 KiB
C++

/* scoped_fd, automatically close a file descriptor
Copyright (C) 2018-2020 Free Software Foundation, Inc.
This file is part of GDB.
This program 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 of the License, or
(at your option) any later version.
This program 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 program. If not, see <http://www.gnu.org/licenses/>. */
#ifndef COMMON_SCOPED_FD_H
#define COMMON_SCOPED_FD_H
#include <unistd.h>
#include "filestuff.h"
/* A smart-pointer-like class to automatically close a file descriptor. */
class scoped_fd
{
public:
explicit scoped_fd (int fd = -1) noexcept : m_fd (fd) {}
scoped_fd (scoped_fd &&other) noexcept
: m_fd (other.m_fd)
{
other.m_fd = -1;
}
~scoped_fd ()
{
if (m_fd >= 0)
close (m_fd);
}
scoped_fd &operator= (scoped_fd &&other)
{
if (m_fd != other.m_fd)
{
if (m_fd >= 0)
close (m_fd);
m_fd = other.m_fd;
other.m_fd = -1;
}
return *this;
}
DISABLE_COPY_AND_ASSIGN (scoped_fd);
ATTRIBUTE_UNUSED_RESULT int release () noexcept
{
int fd = m_fd;
m_fd = -1;
return fd;
}
/* Like release, but return a gdb_file_up that owns the file
descriptor. On success, this scoped_fd will be released. On
failure, return NULL and leave this scoped_fd in possession of
the fd. */
gdb_file_up to_file (const char *mode) noexcept
{
gdb_file_up result (fdopen (m_fd, mode));
if (result != nullptr)
m_fd = -1;
return result;
}
int get () const noexcept
{
return m_fd;
}
private:
int m_fd;
};
#endif /* COMMON_SCOPED_FD_H */