Binutils with MCST patches
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Pedro Alves c053b65441 Initialize gdb::optional empty payload to quiet false -Wmaybe-uninitialized warnings
Commit ecfb656c37 ("dwarf2read.c: Make dir_index and
file_name_index strong typedefs") added a use of gdb::optional that
triggers bogus -Wmaybe-uninitialized warnings:

GCC trunk is complaining like this:

  ../../binutils-gdb/gdb/dwarf2read.c: In function void read_formatted_entries(bfd*, const gdb_byte**, line_header*, const comp_unit_head*, void (*)(line_header*, const char*, dir_index, unsigned int, unsigned int)):
  ../../binutils-gdb/gdb/dwarf2read.c:17779:65: error: fe.file_entry::length may be used uninitialized in this function [-Werror=maybe-uninitialized]
	 callback (lh, fe.name, fe.d_index, fe.mod_time, fe.length);
								   ^
  ../../binutils-gdb/gdb/dwarf2read.c:17779:65: error: *((void*)& fe +8) may be used uninitialized in this function [-Werror=maybe-uninitialized]
  ../../binutils-gdb/gdb/dwarf2read.c:17779:65: error: fe.file_entry::mod_time may be used uninitialized in this function [-Werror=maybe-uninitialized]
  ../../binutils-gdb/gdb/dwarf2read.c:17779:65: error: fe.file_entry::name may be used uninitialized in this function [-Werror=maybe-uninitialized]

While some older GCCs are complaining like this:

  ../../binutils-gdb/gdb/dwarf2read.c: In function void read_formatted_entries(bfd*, const gdb_byte**, line_header*, const comp_unit_head*, void (*)(line_header*, const char*, dir_index, unsigned int, unsigned int)):
  ../../binutils-gdb/gdb/dwarf2read.c:17779:65: error: uint may be used uninitialized in this function [-Werror=maybe-uninitialized]
	 callback (lh, fe.name, fe.d_index, fe.mod_time, fe.length);

Looking around the web, I see that boost's optional implementation
triggers this kind of issue often too.  See:

  http://www.boost.org/doc/libs/1_63_0/libs/optional/doc/html/boost_optional/tutorial/gotchas/false_positive_with__wmaybe_uninitialized.html

I noticed that replacing the gdb::optional uses with real C++17
std::optional uses against GCC 7/trunk makes the warnings go away.
Looking at the implementation, AFAICS, libstdc++ always initializes
its "empty" union payload member (_M_empty, which is defined as an
empty class, like ours).  I.e., all payload types have this ctor:

    struct _Optional_payload.....
    {
      constexpr _Optional_payload()
	: _M_empty() {}

The constexpr makes a diference too.  Without it, GCC7 still warns.

So I'm applying the same treatment to our gdb::optional.

gdb/ChangeLog:
2017-04-05  Pedro Alves  <palves@redhat.com>

	* common/gdb_optional.h (optional::optional): Make constexpr and
	initialize m_dummy.
2017-04-05 01:28:06 +01:00
bfd Automatic date update in version.in 2017-04-05 00:00:36 +00:00
binutils Support ELF SHF_GNU_MBIND and PT_GNU_MBIND_XXX 2017-04-04 09:06:04 -07:00
config picflag.m4 high bit set in comment 2017-01-05 00:02:57 +10:30
cpu Update the openrisc previous program counter (ppc) when running code in the cgen based simulator. 2017-03-20 15:33:51 +00:00
elfcpp Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
etc update-copyright.py for binutils 2017-01-05 00:03:07 +10:30
gas Support ELF SHF_GNU_MBIND and PT_GNU_MBIND_XXX 2017-04-04 09:06:04 -07:00
gdb Initialize gdb::optional empty payload to quiet false -Wmaybe-uninitialized warnings 2017-04-05 01:28:06 +01:00
gold Mips: Fix TLS LDM GOT entry. 2017-03-15 16:51:35 -07:00
gprof Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
include Support ELF SHF_GNU_MBIND and PT_GNU_MBIND_XXX 2017-04-04 09:06:04 -07:00
intl Regen intl/configure 2015-08-31 12:53:36 +09:30
ld PR ld/21233: Avoid sweeping forced-undefined symbols in section GC 2017-04-04 23:21:44 +01:00
libdecnumber Remove leading/trailing white spaces in ChangeLog 2015-07-24 04:16:47 -07:00
libiberty cplus_demangle_fill_component: Handle DEMANGLE_COMPONENT_RVALUE_REFERENCE 2017-03-27 14:18:41 +01:00
opcodes RISC-V: Resurrect GP-relative disassembly hints 2017-04-04 08:29:16 -07:00
readline Improve MinGW support in Readline 2016-09-17 11:50:37 +03:00
sim Fix bug with cmn/adds where C flag was incorrectly set. 2017-03-25 20:32:02 -07:00
texinfo
zlib Sync ZLIB with FSF GCC sources, bringing in version 1.2.11. 2017-02-20 12:52:22 +00:00
.cvsignore
.gitattributes Add a .gitattributes file for use with git-merge-changelog 2014-07-25 18:07:23 -04:00
.gitignore Add archives and make stamps to the .gitignore file. 2016-09-27 15:10:42 +01:00
COPYING
COPYING.LIB
COPYING.LIBGLOSS 2013-01-07 Jeff Johnston <jjohnstn@redhat.com> 2013-01-07 21:39:26 +00:00
COPYING.NEWLIB 2013-10-01 Jeff Johnston <jjohnstn@redhat.com> 2013-10-01 18:14:04 +00:00
COPYING3
COPYING3.LIB
ChangeLog IA16 support 2017-04-03 09:13:19 -07:00
MAINTAINERS Update description of ownership of files in include/ 2014-11-04 16:14:14 -08:00
Makefile.def Sync top-level make and configure files with FSF GCC mainline versions. 2017-01-23 11:55:48 +00:00
Makefile.in Sync top-level make and configure files with FSF GCC mainline versions. 2017-01-23 11:55:48 +00:00
Makefile.tpl Sync top-level make and configure files with FSF GCC mainline versions. 2017-01-23 11:55:48 +00:00
README
README-maintainer-mode
compile Update from upstream Automake 2014-11-16 13:43:48 +01:00
config-ml.in Sync toplevel files with GCC 2015-07-27 07:49:05 -07:00
config.guess Sync top level config files with master versions in the FSF config project. 2017-03-22 14:01:03 +00:00
config.rpath
config.sub IA16 support 2017-04-03 09:13:19 -07:00
configure Sync top-level make and configure files with FSF GCC mainline versions. 2017-01-23 11:55:48 +00:00
configure.ac Sync top-level make and configure files with FSF GCC mainline versions. 2017-01-23 11:55:48 +00:00
depcomp Update from upstream Automake 2014-11-16 13:43:48 +01:00
djunpack.bat
install-sh Update from upstream Automake 2014-11-16 13:43:48 +01:00
libtool.m4 Sync top-level btool.m4 with GCC 2016-01-12 08:44:52 -08:00
ltgcc.m4
ltmain.sh PR target/59788 2014-02-06 11:01:57 +01:00
ltoptions.m4
ltsugar.m4
ltversion.m4
lt~obsolete.m4
makefile.vms
missing Update from upstream Automake 2014-11-16 13:43:48 +01:00
mkdep
mkinstalldirs Update from upstream Automake 2014-11-16 13:43:48 +01:00
move-if-change Update `move-if-change' from gnulib 2014-11-16 17:04:02 +01:00
setup.com
src-release.sh fix gdb version parsing in src-release.sh 2016-01-17 10:01:55 +04:00
symlink-tree
ylwrap Update from upstream Automake 2014-11-16 13:43:48 +01:00

README

		   README for GNU development tools

This directory contains various GNU compilers, assemblers, linkers, 
debuggers, etc., plus their support routines, definitions, and documentation.

If you are receiving this as part of a GDB release, see the file gdb/README.
If with a binutils release, see binutils/README;  if with a libg++ release,
see libg++/README, etc.  That'll give you info about this
package -- supported targets, how to use it, how to report bugs, etc.

It is now possible to automatically configure and build a variety of
tools with one command.  To build all of the tools contained herein,
run the ``configure'' script here, e.g.:

	./configure 
	make

To install them (by default in /usr/local/bin, /usr/local/lib, etc),
then do:
	make install

(If the configure script can't determine your type of computer, give it
the name as an argument, for instance ``./configure sun4''.  You can
use the script ``config.sub'' to test whether a name is recognized; if
it is, config.sub translates it to a triplet specifying CPU, vendor,
and OS.)

If you have more than one compiler on your system, it is often best to
explicitly set CC in the environment before running configure, and to
also set CC when running make.  For example (assuming sh/bash/ksh):

	CC=gcc ./configure
	make

A similar example using csh:

	setenv CC gcc
	./configure
	make

Much of the code and documentation enclosed is copyright by
the Free Software Foundation, Inc.  See the file COPYING or
COPYING.LIB in the various directories, for a description of the
GNU General Public License terms under which you can copy the files.

REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info
on where and how to report problems.