See e3fdc37049: in C++ we generate
explicitly the code for the default action instead of simply copying
blindly the semantic value buffer. This is important when copying
raw memory is not enough, as exemplified by move-only types.
This is currently tested by examples/c++/variant.yy and variant-11.yy.
But it is safer to also have a test in the main test suite.
* tests/local.at (AT_REQUIRE_CXX_STD): Fix.
(AT_BISON_OPTION_PUSHDEFS, AT_BISON_OPTION_POPDEFS): Define/undefine
AT_BISON_OPTIONS.
* tests/c++.at (Default action): New.
Currently, when we quote the source file, we indent it with one space,
and preserve tabulations, so there is a discrepancy and the visual
rendering is bad. One way out is to indent with a tab instead of a
space, but then this space can be used for more information. This is
what GCC9 does. Let's play copy cats.
See
https://lists.gnu.org/archive/html/bison-patches/2019-04/msg00025.htmlhttps://developers.redhat.com/blog/2019/03/08/usability-improvements-in-gcc-9/https://gcc.gnu.org/onlinedocs/gccint/Guidelines-for-Diagnostics.html#Guidelines-for-Diagnostics
* src/location.c (location_caret): Prefix quoted lines with the line
number and a pipe, fitting 8 columns.
* tests/actions.at, tests/c++.at, tests/conflicts.at,
* tests/diagnostics.at, tests/input.at, tests/java.at,
* tests/named-refs.at, tests/reduce.at, tests/regression.at,
* tests/sets.at: Adjust expectations.
Partly by "./build-aux/update-test tests/testsuite.dir/*/testsuite.log"
repeatedly, and partly by hand.
Currently the caller must specify the ./ prefix to its command. Let's
avoid that: it will be nicer to read, make it easier to have a version
that works for Java and C/C++.
* tests/local.at (AT_PARSER_CHECK): Prefix the command with ./.
Adjust callers.
Reported by Derek Clegg.
http://lists.gnu.org/archive/html/bug-bison/2019-01/msg00004.html
* configure.ac (warn_common): Add -Wimplicit-fallthrough.
This does trigger failures in the test suite.
* data/skeletons/glr.c, data/skeletons/lalr1.cc,
* data/skeletons/yacc.c, tests/c++.at:
Make fall-throws explicit.
This line:
slice<stack_symbol_type, stack_type> slice (yystack_, yylen);
triggers warnings:
parse.h:1790:11: note: shadowed declaration is here
Reported by Frank Heckenbach.
http://lists.gnu.org/archive/html/bug-bison/2019-01/msg00002.html
* configure.ac (warn_c): Move -Wshadow to...
(warn_common): here.
* data/skeletons/stack.hh (slice): Define as an inner class of stack.
* data/skeletons/lalr1.cc: Adjust.
Rename the variable as 'range' instead of 'slice'.
Commit 90a8537e62 was right, but issued
two error messages. Commit 80ef7e7639
tried to address that by mapping yychar and yytoken to empty, but that
completely breaks the invariants of glr.c. In particular, yygetToken
can be called repeatedly and is expected to return the latest result,
unless yytoken is YYEMPTY. Since the previous attempt was "recording"
that the token was coming from an exception by setting it to YYEMPTY,
instead of getting again the faulty token, we fetched another one.
Rather, revert to the first approach: map yytoken to "invalid token",
but record in yychar the fact that we come from an exception thrown in
the scanner.
* data/skeletons/glr.c (YYFAULTYTOK): New.
(yygetToken): Use it to record syntax errors from the scanner.
* tests/c++.at (Syntax error as exception): In addition to checking
syntax_error with error recovery, make sure it also behaves as
expected without.
Reported by Askar Safin.
https://lists.gnu.org/archive/html/bison-patches/2019-01/msg00000.html
* data/skeletons/glr.c (yygetToken): Return YYEMPTY when an exception
is thrown.
* data/skeletons/lalr1.cc: Log when an exception is caught.
* tests/c++.at (Syntax error as exception): Be sure to recover from
error before triggering another error.
Suggested by Wolfgang Thaller.
http://lists.gnu.org/archive/html/bug-bison/2018-12/msg00081.html
* data/c++.m4 (basic_symbol, by_type): Instead of provide either move
or copy constructor, always provide the copy one.
* tests/c++.at (C++ Variant-based Symbols Unit Tests): Check it.
Currently the following piece of code crashes (with parse.assert),
because we don't record that s was moved-from, and we invoke its dtor.
{
auto s = parser::make_INT (42);
auto s2 = std::move (s);
}
Reported by Wolfgang Thaller.
http://lists.gnu.org/archive/html/bug-bison/2018-12/msg00077.html
* data/c++.m4 (by_type): Provide a move-ctor.
(basic_symbol): Be sure not to read a moved-from value.
* tests/c++.at (C++ Variant-based Symbols Unit Tests): Check this case.
* tests/c++.at: Use AT_YYLEX_PROTOTYPE etc.
Which requires that we use the same argument names (lvalp, etc.).
* tests/local.at (AT_NAME_PREFIX): Fix regex.
Reported by Uxio Prego.
https://lists.gnu.org/archive/html/help-bison/2018-11/msg00031.html
We also need to move the unreachable 'goto' to a reachable place,
otherwise clang complains about the code being unreachable anyway.
See also https://bugs.llvm.org/show_bug.cgi?id=39736.
Interestingly, we don't have to apply that trick to
`#define YYCDEBUG if (false) std::cerr`, clang does not warn when the
code comes from macro expansion.
* configure.ac: Use -Wunreachable-code when supported.
* data/lalr1.cc, data/yacc.c: Pacify clang's warning about `if (0)`
by using a macro.
Another possibility was to move this statement to a reachable place.
* tests/actions.at, tests/c++.at: Avoid generating unreachable code.
In some casing, once we moved a stack symbol, we forget to mark the
source stack symbol as emptied. As a consequence, it may be destroyed
a second time.
This happens when the stack has to be resized.
* data/lalr1.cc (stack_symbol_type::stack_symbol_type): Record that
the source was emptied.
(stack_symbol_type::operator=): Likewise.
* tests/c++.at (C++ Variant-based Symbols Unit Tests): Force the stack
to be resized. Check its content.
Currently we use "<dir><api.location.file>" as \file argument, and as
base for the CPP guard. This is not nice when <dir> is absolute, in
which case it is expected that the user will use api.location.include
to get something nicer. If defined, use that name instead.
* data/location.cc (b4_location_path): New.
Use it.
* tests/c++.at (Shared locations): Check the guard and Doxygen doc.
Users may want to generate the location file elsewhere, say
$top_srcdir/include/ast/location.hh. Yet, we should not generate
`#include "$top_srcdir/include/ast/location.hh"` but probably
something like `#include <ast/location.hh>`, or `#include
"ast/location.hh", or `#include <location.hh>`. It entirely depends
on the compiler flags (-I/-isystem) that are used. Bison cannot guess
what is expected, so let's give the user a means to tell how the
location file should be included.
* data/location.cc (b4_location_file): New.
* data/glr.cc, data/lalr1.cc: Use it.
The forthcoming automove feature, to be properly checked, will require
that we can rely on the value of a moved-from string, which is not
something the C++ standard guarantees. So introduce our own wrapper.
Suggested by Frank Heckenbach.
https://lists.gnu.org/archive/html/bison-patches/2018-09/msg00111.html
* tests/c++.at (Variants): Introduce and use a new 'string' class.
The 'Variants' tests are well suited to check support for move, and in
particular for the forthcoming automove feature. But the tests were
written to show the best practice in C++98, using swap:
list "," item { std::swap ($$, $1); $$.push_back ($3); }
This cannot work with std::move. So, make this example simpler, based
on regular assignment instead of swap, which is a regression for
C++98 (as the new traces show), but will be an improvement for modern
C++ with automove.
* tests/c++.at (Variants): Stop using swap.
We don't generate a header file, so remove the 'require' code section.
Adjust expectations.
The code was already using midrule only, never mid_rule. This is
simpler to remember, and matches a similar change we made from
look-ahead to lookahead.
* NEWS, doc/bison.texi, src/reader.c, src/scan-code.h, src/scan-code.l
* tests/actions.at, tests/c++.at, tests/existing.at: here.
This is much of course more efficient than in the matrix of the CI (or
on our own machines), but a bit more tedious.
* configure.ac (CXX03_CXXFLAGS, CXX11_CXXFLAGS, CXX14_CXXFLAGS)
(CXX17_CXXFLAGS, CXX2A_CXXFLAGS, STDCXX_FLAGS): New.
* tests/atlocal.in: Receive them.
* tests/local.at (AT_FOR_EACH_CXX): New.
* tests/c++.at: Use AT_FOR_EACH_CXX.
Reported by Frank Heckenbach.
http://lists.gnu.org/archive/html/bug-bison/2018-03/msg00002.html
Actually the assignment operator should never be needed: the C++98
requirements for vector::push_back is CopyInsertable, which does not require
an assignment operator. However, libstdc++ shipped with GCC up to (and
including) 6 uses the assignment operator (which affects Clang on top of
libstdc++, but also ICC). So let's keep it for legacy C++.
See https://gcc.godbolt.org/z/q0XXmC.
* data/lalr1.cc (stack_symbol_type::operator=): Remove.
* data/c++.m4 (basic_symbol::operator=): Ditto.
* tests/c++.at (C++ Variant-based Symbols Unit Tests): Adjust.
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.
With recent compilers:
input.yy:49:5: error: definition of implicit copy assignment
operator for 'Object' is deprecated because
it has a user-declared destructor
[-Werror,-Wdeprecated]
~Object ()
^
input.yy:130:35: note: in implicit copy assignment operator for
'Object' first required here
{ yylhs.value.as< Object > () = yystack_[0].value.as< Object > (); }
* tests/c++.at (Object): Add missing assignment operator.
Sometimes `inline` would be used in *.cc files on symbols that are not
exported (useless but harmless), and sometimes on exported symbols
such as the constructor of syntax_error (harmful: linking fails).
Reported several times, including:
- by Dennis T
http://lists.gnu.org/archive/html/bug-bison/2016-03/msg00002.html
- by Frank Heckenbach
https://savannah.gnu.org/patch/?9616
* data/c++.m4 (b4_inline): New: expands to `inline` or nothing.
Use it where appropriate.
* data/lalr1.cc: Use it where appropriate.
* tests/c++.at (Syntax error as exception): Put the scanner in another
compilation unit to exercise the constructor of syntax_error.
* data/lalr1.cc, doc/bison.texi, etc/bench.pl.in, examples/variant.yy,
* tests/actions.at, tests/atlocal.in, tests/c++.at, tests/headers.at,
* tests/local.at, tests/types.at:
Don't use std::endl, it flushes uselessly, and is considered bad
style.
Sun C 5.13 SunOS_sparc 2014/10/20 reports errors on tests 430-432.
Reported by Dennis Clarke.
<http://lists.gnu.org/archive/html/bug-bison/2015-01/msg00087.html>
* tests/c++.at (Variants): Be sure to emit operator<< before using it:
use "%code top" rather than "%code".
Prefer std::vector to std::list.
Do not define anything in std::, to avoid undefined behavior.
This is consistent with what is done with yacc.c and glr.c. Because
it also avoids that the stack needs to be resized very soon, it should
help keeping tests about destructors more reliable.
Indeed, if the stack is created too small, very soon the C++ library
needs to enlarge it, which means creating a new one, copying the
elements from the initial one onto it, and then destroy the elements
of the initial stack: that would be a spurious call to a destructor.
Reported by Thomas Jahns.
http://lists.gnu.org/archive/html/bug-bison/2015-01/msg00059.html
* data/stack.hh (stack::stack): Reserve 200 slots.
* tests/c++.at: Remove traces of stack expansions.
