This commit brings all the changes made by running gdb/copyright.py
as per GDB's Start of New Year Procedure.
For the avoidance of doubt, all changes in this commits were
performed by the script.
Say we use a gcc version that (while supporting c++11) does not support c++11
by default, and needs an -std setting to enable it.
If gdb would use the default AX_CXX_COMPILE_STDCXX from autoconf-archive, then
we'd have:
...
CXX="g++ -std=gnu++11"
...
That mechanism however has the following problem (quoting from commit
0bcda68539):
...
the top level Makefile passes CXX down to subdirs, and that overrides whatever
gdb/Makefile may set CXX to. The result would be that a make invocation from
the build/gdb/ directory would use "g++ -std=gnu++11" as expected, while a
make invocation at the top level would not.
...
Commit 0bcda68539 fixes this by using a custom AX_CXX_COMPILE_STDCXX which
does:
...
CXX=g++
CXX_DIALECT=-std=gnu++11
...
The problem reported in PR28318 is that using the custom instead of the
default AX_CXX_COMPILE_STDCXX makes the configure test for std::thread
support fail.
We could simply add $CXX_DIALECT to the test for std::thread support, but
that would have to be repeated for each added c++ support test.
Instead, fix this by doing:
...
CXX="g++ -std=gnu++11"
CXX_DIALECT=-std=gnu++11
...
This is somewhat awkward, since it results in -std=gnu++11 occuring twice in
some situations:
...
$ touch src/gdb/dwarf2/read.c
$ ( cd build/gdb; make V=1 dwarf2/read.o )
g++-4.8 -std=gnu++11 -x c++ -std=gnu++11 ...
...
However, both settings are needed:
- the switch in CXX for the std::thread tests (and other tests)
- the switch in CXX_DIALECT so it can be appended in Makefiles, to
counteract the fact that the top-level Makefile overrides CXX
The code added in gdb/ax_cxx_compile_stdcxx.m4 is copied from the default
AX_CXX_COMPILE_STDCXX from autoconf-archive.
Tested on x86_64-linux.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=28318
This commits the result of running gdb/copyright.py as per our Start
of New Year procedure...
gdb/ChangeLog
Update copyright year range in copyright header of all GDB files.
This commit applies all changes made after running the gdb/copyright.py
script.
Note that one file was flagged by the script, due to an invalid
copyright header
(gdb/unittests/basic_string_view/element_access/char/empty.cc).
As the file was copied from GCC's libstdc++-v3 testsuite, this commit
leaves this file untouched for the time being; a patch to fix the header
was sent to gcc-patches first.
gdb/ChangeLog:
Update copyright year range in all GDB files.
This file provides the AX_CXX_COMPILE_STDCXX macro. In the context of
the following patch, I wanted to build and test GDB in c++17 mode. The
version of the macro we have in the repo does not support detecting
c++17 compilers, but the upstream version has been updated to do so.
Since we have local modifications to the file, I had to reconcile our
modifications and the updated upstream version (which was relatively
straightforward).
gdb/ChangeLog:
* ax_cxx_compile_stdcxx.m4: Sync with upstream.
* configure: Re-generate.
This applies the second part of GDB's End of Year Procedure, which
updates the copyright year range in all of GDB's files.
gdb/ChangeLog:
Update copyright year range in all GDB files.
Use AX_CXX_COMPILE_STDCXX to detect if the compiler supports C++11,
and if -std=xxx switches are necessary to enable C++11.
We need to tweak AX_CXX_COMPILE_STDCXX a bit though. Pristine
upstream AX_CXX_COMPILE_STDCXX appends -std=gnu++11 to CXX directly.
That doesn't work for us, because the top level Makefile passes CXX
down to subdirs, and that overrides whatever gdb/Makefile may set CXX
to. The result would be that a make invocation from the build/gdb/
directory would use "g++ -std=gnu++11" as expected, while a make
invocation at the top level would not.
So instead of having AX_CXX_COMPILE_STDCXX set CXX directly, tweak it
to AC_SUBST a separate variable -- CXX_DIALECT -- and use '$(CXX)
(CXX_DIALECT)' to compile/link.
Confirmed that this enables C++11 starting with gcc 4.8, the first gcc
release with full C++11 support.
Also confirmed that configure errors out gracefully with older GCC
releases:
checking whether /opt/gcc-4.7/bin/g++ supports C++11 features by default... no
checking whether /opt/gcc-4.7/bin/g++ supports C++11 features with -std=gnu++11... no
checking whether /opt/gcc-4.7/bin/g++ supports C++11 features with -std=gnu++0x... no
checking whether /opt/gcc-4.7/bin/g++ supports C++11 features with -std=c++11... no
checking whether /opt/gcc-4.7/bin/g++ supports C++11 features with -std=c++0x... no
checking whether /opt/gcc-4.7/bin/g++ supports C++11 features with +std=c++11... no
checking whether /opt/gcc-4.7/bin/g++ supports C++11 features with -h std=c++11... no
configure: error: *** A compiler with support for C++11 language features is required.
Makefile:9451: recipe for target 'configure-gdb' failed
make[1]: *** [configure-gdb] Error 1
make[1]: Leaving directory '/home/pedro/brno/pedro/gdb/mygit/cxx-convertion/build-gcc-4.7'
If we need to revert back to making C++11 optional, all that's
necessary is to change the "mandatory" to "optional" in configure.ac
and regenerate configure (both gdb and gdbserver).
gdb/ChangeLog:
2016-10-28 Pedro Alves <palves@redhat.com>
* Makefile.in (CXX_DIALECT): Get from configure.
(COMPILE.pre, CC_LD): Append $(CXX_DIALECT).
(FLAGS_TO_PASS): Pass CXX_DIALECT.
* acinclude.m4: Include ax_cxx_compile_stdcxx.m4.
* ax_cxx_compile_stdcxx.m4: Add FSF copyright header. Set and
AC_SUBST CXX_DIALECT instead of changing CXX/CXXCPP.
* configure.ac: Call AX_CXX_COMPILE_STDCXX.
* config.in: Regenerate.
* configure: Regenerate.
gdb/gdbserver/ChangeLog:
2016-10-28 Pedro Alves <palves@redhat.com>
* Makefile.in (CXX_DIALECT): Get from configure.
(COMPILE.pre, CC_LD): Append $(CXX_DIALECT).
* acinclude.m4: Include ../ax_cxx_compile_stdcxx.m4.
* configure.ac: Call AX_CXX_COMPILE_STDCXX.
* config.in: Regenerate.
* configure: Regenerate.
This macro throws C++11 code at the compiler in order to check whether
it supports C++11. final/override, rvalue references, static_assert,
decltype, auto, constexpr, etc., and adds -std=gnu++11 to CXX if
necessary.
Nothing uses the macro yet. Simply adding it as separate preliminary
step because we'll need local changes.
gdb/ChangeLog
2016-10-28 Pedro Alves <palves@redhat.com>
* ax_cxx_compile_stdcxx.m4: New file.
