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Tom de Vries 866b34a12d [gdb/build] Fix Wmaybe-uninitialized in gdb_optional.h
When building with CFLAGS/CXXFLAGS="-O2 -g -Wall", we run into:
...
In file included from src/gdb/exceptions.h:23,
                 from src/gdb/utils.h:24,
                 from src/gdb/defs.h:630,
                 from src/gdb/record-btrace.c:22:
src/gdb/ui-out.h: In function 'void btrace_insn_history(ui_out*, \
  const btrace_thread_info*, const btrace_insn_iterator*, \
  const btrace_insn_iterator*, gdb_disassembly_flags)':
src/gdb/ui-out.h:352:18: warning: \
  'asm_list.ui_out_emit_type<ui_out_type_list>::m_uiout' may be used \
  uninitialized in this function [-Wmaybe-uninitialized]
  352 |     m_uiout->end (Type);
      |     ~~~~~~~~~~~~~^~~~~~
src/gdb/record-btrace.c:795:35: note: \
  'asm_list.ui_out_emit_type<ui_out_type_list>::m_uiout' was declared here
  795 |   gdb::optional<ui_out_emit_list> asm_list;
      |                                   ^~~~~~~~
...

This is reported as PR gcc/80635 - "[8/9/10/11 regression] std::optional and
bogus -Wmaybe-uninitialized warning".

Silence the warning by using the workaround suggested here (
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80635#c53 ):
...
   union
   {
     struct { } m_dummy;
     T m_item;
+    volatile char dont_use; // Silences -Wmaybe-uninitialized warning.
   };
...

Build on x86_64-linux.

gdbsupport/ChangeLog:

2020-07-28  Tom de Vries  <tdevries@suse.de>

	PR build/26281
	* gdb_optional.h (class optional): Add volatile member to union
	contaning m_dummy and m_item.
2020-07-28 15:07:44 +02:00
bfd PR25022 testcase segfault for generic ELF linker targets 2020-07-28 16:56:14 +09:30
binutils PKG_CHECK_MODULES: Check if $pkg_cv_[]$1[]_LIBS works 2020-07-28 03:56:34 -07:00
config PKG_CHECK_MODULES: Check if $pkg_cv_[]$1[]_LIBS works 2020-07-28 03:56:34 -07:00
contrib
cpu Add markers for binutils 2.35 branch 2020-07-04 10:16:22 +01:00
elfcpp Add markers for binutils 2.35 branch 2020-07-04 10:16:22 +01:00
etc
gas x86: Handle {disp32} for (%bp)/(%ebp)/(%rbp) 2020-07-28 03:55:53 -07:00
gdb PKG_CHECK_MODULES: Check if $pkg_cv_[]$1[]_LIBS works 2020-07-28 03:56:34 -07:00
gdbserver Don't unnecessarily redefine 'socklen_t' type in MinGW builds. 2020-07-26 19:35:48 +03:00
gdbsupport [gdb/build] Fix Wmaybe-uninitialized in gdb_optional.h 2020-07-28 15:07:44 +02:00
gnulib
gold [GOLD] Power10 stub selection 2020-07-27 22:31:37 +09:30
gprof Update Turkish translation in the gprof sub-directory 2020-07-09 14:25:11 +01:00
include libctf, link: tie in the deduplicating linker 2020-07-22 18:02:19 +01:00
intl
ld More just-syms changes 2020-07-28 13:09:20 +09:30
libctf libctf: compilation failure on MinGW due to missing errno values 2020-07-26 16:11:36 -07:00
libdecnumber
libiberty Sync config, include and libiberty with GCC 2020-06-24 16:52:48 -07:00
opcodes Updated German translation for the opcodes sub-directory 2020-07-24 10:14:22 +01:00
readline Update readline/README to mention patchlevel 2020-06-30 15:17:07 -06:00
sim sim/igen: Fix linker error with -fno-common 2020-07-03 21:03:47 +02:00
texinfo
zlib
.cvsignore
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ChangeLog PKG_CHECK_MODULES: Check if $pkg_cv_[]$1[]_LIBS works 2020-07-28 03:56:34 -07:00
compile
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configure config/debuginfod.m4: Use PKG_CHECK_MODULES 2020-07-24 15:16:20 -04:00
configure.ac config/debuginfod.m4: Use PKG_CHECK_MODULES 2020-07-24 15:16:20 -04:00
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		   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.