Files
bison/tests/atlocal.in
Akim Demaille f19ecae3b2 lalr1.cc: support move semantics
Modern C++ (i.e., C++11 and later) introduced "move only" types: types such
as std::unique_ptr<T> that can never be duplicated.  They must never be
copied (by assignments and constructors), they must be "moved".  The
implementation of lalr1.cc used to copy symbols (including their semantic
values).  This commit ensures that values are only moved in modern C++, yet
remain compatible with C++98/C++03.

Suggested by Frank Heckenbach, who provided a full implementation on
top of C++17's std::variant.
See http://lists.gnu.org/archive/html/bug-bison/2018-03/msg00002.html,
and https://lists.gnu.org/archive/html/bison-patches/2018-04/msg00002.html.

Symbols (terminal/non terminal) are handled by several functions that used
to take const-refs, which resulted eventually in a copy pushed on the stack.
With modern C++ (C++11 and later) the callers must use std::move, and the
callees must take their arguments as rvalue refs (foo&&).  In order to avoid
duplicating these functions to support both legacy C++ and modern C++, let's
introduce macros (YY_MOVE, YY_RVREF, etc.)  that rely on copy-semantics for
C++98/03, and move-semantics for modern C++.

That's easy for inner types, when the parser's functions pass arguments to
each other.  Functions facing the user (make_NUMBER, make_STRING, etc.)
should support both rvalue-refs (for instance to support move-only types:
make_INT (std::make_unique<int> (1))), and lvalue-refs (so that we can pass
a variable: make_INT (my_int)).  To avoid the multiplication of the
signatures (there is also the location), let's take the argument by value.

See:
https://lists.gnu.org/archive/html/bison-patches/2018-09/msg00024.html.

* data/c++.m4 (b4_cxx_portability): New.
(basic_symbol): In C++11, replace copy-ctors with move-ctors.
In C++11, replace copies with moves.
* data/lalr1.cc (stack_symbol_type, yypush_): Likewise.
Use YY_MOVE to avoid useless copies.
* data/variant.hh (variant): Support move-semantics.
(make_SYMBOL): In C++11, in order to support both read-only lvalues,
and rvalues, take the argument as a copy.
* data/stack.hh (yypush_): Use rvalue-refs in C++11.
* tests/c++.at: Use move semantics.

* tests/headers.at: Adjust to the new macros (YY_MOVE, etc.).

* configure.ac (CXX98_CXXFLAGS, CXX11_CXXFLAGS, CXX14_CXXFLAGS)
(CXX17_CXXFLAGS, ENABLE_CXX11): New.
* tests/atlocal.in: Receive them.

* examples/variant.yy: Don't define things in std.
* examples/variant-11.test, examples/variant-11.yy: New.
Check the support of move-only types.
* examples/README, examples/local.mk: Adjust.
2018-09-13 19:01:33 +02:00

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# @configure_input@ -*- shell-script -*-
# Configurable variable values for Bison test suite.
# Copyright (C) 2000-2015, 2018 Free Software Foundation, Inc.
#
# 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/>.
# We need 'config.h' (builddir/lib), and the gnulib headers (srcdir/lib).
CPPFLAGS="-I$abs_top_srcdir/lib -I$abs_top_builddir/lib @CPPFLAGS@"
# Don't just check if $POSIXLY_CORRECT is set, as Bash, when launched
# as /bin/sh, sets the shell variable POSIXLY_CORRECT to y, but not
# the environment variable.
if env | grep '^POSIXLY_CORRECT=' >/dev/null; then
POSIXLY_CORRECT_IS_EXPORTED=true
else
POSIXLY_CORRECT_IS_EXPORTED=false
fi
## ------------------- ##
## C/C++ Compilation. ##
## ------------------- ##
: ${CC='@CC@'}
: ${CXX='@CXX@'}
# Is the compiler GCC?
GCC='@GCC@'
# Sometimes a test group needs to ignore gcc warnings, so it locally
# sets CFLAGS to this.
NO_WERROR_CFLAGS='@CFLAGS@ @WARN_CFLAGS@ @WARN_CFLAGS_TEST@'
NO_WERROR_CXXFLAGS='@CXXFLAGS@ @WARN_CXXFLAGS@ @WARN_CXXFLAGS_TEST@'
WNO_DEPRECATED_CXXFLAGS='@WNO_DEPRECATED_CXXFLAGS@'
# But most of the time, we want -Werror.
CFLAGS="$NO_WERROR_CFLAGS @WERROR_CFLAGS@"
CXXFLAGS="$NO_WERROR_CXXFLAGS @WERROR_CXXFLAGS@"
# If 'exit 77'; skip all C++ tests; otherwise ':'.
BISON_CXX_WORKS='@BISON_CXX_WORKS@'
# Compiler flags to disable exception support.
NO_EXCEPTIONS_CXXFLAGS='@NO_EXCEPTIONS_CXXFLAGS@'
# Requiring a specific C++ standard.
CXX11_CXXFLAGS='@CXX11_CXXFLAGS@'
# Be sure that the C++ compiler is not broken because of gnulib. This
# cannot be checked in configure (gnulib is not parameterized yet),
# and checking this in every C++ test in AC_COMPILE_CXX is too costly.
#
# http://lists.gnu.org/archive/html/bug-bison/2013-06/msg00001.html
#
# FIXME: Check (say 2014) whether this is still needed.
if $BISON_CXX_WORKS; then
# See AT_DATA_SOURCE_PROLOGUE.
cat >conftest.cc <<EOF
#include <config.h>
/* We don't need perfect functions for these tests. */
#undef malloc
#undef memcmp
#undef realloc
#include <iostream>
int main ()
{
std::cout << "Works\n";
}
EOF
$CXX $CXXFLAGS $CPPFLAGS $LDFLAGS $LIBS -o conftest conftest.cc
case $? in
0);;
*) BISON_CXX_WORKS="as_fn_error 77 cannot-compile-simple-program";;
esac
rm -fr conftest*
fi
# Whether the compiler supports POSIXLY_CORRECT defined.
: ${C_COMPILER_POSIXLY_CORRECT='@C_COMPILER_POSIXLY_CORRECT@'}
: ${CXX_COMPILER_POSIXLY_CORRECT='@CXX_COMPILER_POSIXLY_CORRECT@'}
if $POSIXLY_CORRECT_IS_EXPORTED; then
$C_COMPILER_POSIXLY_CORRECT ||
BISON_C_WORKS="as_fn_error 77 POSIXLY_CORRECT"
$CXX_COMPILER_POSIXLY_CORRECT ||
BISON_CXX_WORKS="as_fn_error 77 POSIXLY_CORRECT"
fi
# Handle --compile-c-with-cxx here, once CXX and CXXFLAGS are known.
if "$at_arg_compile_c_with_cxx"; then
CC_IS_CXX=1
CC=$CXX
NO_WERROR_CFLAGS=$NO_WERROR_CXXFLAGS
CFLAGS="$CXXFLAGS $WNO_DEPRECATED_CXXFLAGS"
BISON_C_WORKS=$BISON_CXX_WORKS
else
CC_IS_CXX=0
fi
## ------- ##
## Other. ##
## ------- ##
# Empty if no javac was found
CONF_JAVAC='@CONF_JAVAC@'
# Empty if no Java VM was found
CONF_JAVA='@CONF_JAVA@'
# We need egrep and perl.
: ${EGREP='@EGREP@'}
: ${PERL='@PERL@'}
# Use simple quotes (lib/quote.c).
LC_CTYPE=C
export LC_CTYPE
# Are special link options needed?
LDFLAGS='@LDFLAGS@'
# Are special libraries needed?
LIBS="$abs_top_builddir/lib/libbison.a @LIBS@ @INTLLIBS@"
# Empty if no xsltproc was found
: ${XSLTPROC='@XSLTPROC@'}
# Don't just check if $POSIXLY_CORRECT is set, as Bash, when launched
# as /bin/sh, sets the shell variable POSIXLY_CORRECT to y, but not
# the environment variable.
: ${C_COMPILER_POSIXLY_CORRECT='@C_COMPILER_POSIXLY_CORRECT@'}
if env | grep '^POSIXLY_CORRECT=' >/dev/null; then
POSIXLY_CORRECT_IS_EXPORTED=true
else
POSIXLY_CORRECT_IS_EXPORTED=false
fi