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.
On some systems (x86_64-pc-solaris2.11), with Developer Studio 12.5's
CC, we get:
".../include/CC/Cstd/vector.cc", line 127: Error: Cannot assign const yy::parser::stack_symbol_type to yy::parser::stack_symbol_type without "yy::parser::stack_symbol_type::operator=(const yy::parser::stack_symbol_type&)";.
".../include/CC/Cstd/vector", line 475: Where: While instantiating "std::vector<yy::parser::stack_symbol_type>::__insert_aux(yy::parser::stack_symbol_type*, const yy::parser::stack_symbol_type&)".
".../include/CC/Cstd/vector", line 475: Where: Instantiated from non-template code.
1 Error(s) detected.
Don't expect __cplusplus to be always defined. If it's not, consider
this is C++98.
Reported by Nelson H. F. Beebe.
* data/c++.m4, data/lalr1.cc, examples/c++/variant.yy, tests/local.at,
* tests/testsuite.h:
An undefined __cplusplus means pre C++11.
* data/lalr1.cc: Fix oldish comment.
* data/stack.hh: Prefer typename for type names.
Use size() instead of duplicating it.
* examples/variant-11.yy, examples/variant.yy (yylex): Use int,
as this is the type of the semantic value.
Currently we emit useless code for places where we might issue user
content, but there is none. This commit avoids this. Besides, some
of the comments looked like implementation details ("Copy the first
part of user declarations"), rather than made for the reader of the
result ("First part of user prologue").
On Bison's parse-gram.c we get:
@@ -76,10 +76,6 @@
#define yynerrs gram_nerrs
-/* Copy the first part of user declarations. */
-
-#line 82 "src/parse-gram.c" /* yacc.c:339 */
-
* data/bison.m4 (b4_define_user_code): Accept a comment to document
the section.
Do not emit any code if the content is empty.
Adjust callers to not emit the comment.
Do not
* data/glr.c, data/glr.cc, data/lalr1.cc, data/lalr1.java, data/yacc.c:
Adjust.
When we introduced variants in Bison, C++ did not have the 'emplace'
functions, and we chose 'build'. Let's align with modern C++ and
promote 'emplace' rather than 'build'.
* data/lalr1.cc, data/variant.hh (emplace): New.
(build): Deprecate in favor of emplace.
* doc/bison.texi: Adjust.
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.
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.
Let's put the definition of position into location.hh, there's no real
value in keeping them separate: they are small, and share the same
requirements.
To help users transition to this new model, still generate position.hh
by default, but as a simple include to location.hh.
* data/location.cc (api.position.file): Accept only 'none' as possible
value.
(position.hh): Make it a stub.
(location.hh): Adjust.
(b4_position_define): Merge into...
(b4_location_define): this.
* data/glr.cc, data/lalr1.cc, tests/input.at, tests/output.at: Adjust.
* data/location.cc: Sort includes.
(b4_position_file, b4_location_file): New.
When there's a file for locations but not for positions, include the
definition of position in the location file.
* data/lalr1.cc (b4_shared_declarations): Include the
position/location file when it exists.
Otherwise, define the class.
* data/glr.cc: Likewise.
* tests/input.at (%define file variables): Check them.
* tests/output.at (C++ output): Check various cases with
api.position.file and api.location.file.
It was not a good idea to generate the file stack.hh. It never was.
But now we have to deal with backward compatibility: if we stop
generating it, the build system of some build system will probably
break.
So offer the user a means to (i) decide what the name of the output
file should be, and (ii) not generate this file at all (its content
will be inline where the parser is defined).
* data/lalr1.cc (b4_percent_define_check_file_complain)
(b4_percent_define_check_file): New.
* data/stack.hh: Generate the file only if api.stack.file is not
empty.
In that case, use it as file name.
* data/lalr1.cc: Adjust to include the right file, or to include
the definition of stack.
* tests/calc.at, tests/output.at: Exercise api.stack.file.
We use both styles, let's stick to a single one. Autoconf uses the
prefix one, let's do the same.
* data/bison.m4, data/c++.m4, data/c-like.m4, data/lalr1.cc,
* data/variant.hh, data/yacc.c: Rename all the b4_*_ macros
as _b4_*.
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.
Currently, in glr.cc, we emit the definitions of basic_symbol and
symbol_type, although there are not used.
* data/c++.m4 (b4_public_types_declare): Extract these definitions from
here, and move them...
(b4_symbol_type_declare): here.
(b4_public_types_declare): Also remove the definition of the symbol
constructors.
* data/lalr1.cc (b4_shared_declarations): Adjust: call
b4_symbol_type_declare and b4_symbol_constructor_declare.
Benchmarks show that it is more efficient to keep this copy
constructor, rather than forcing the use of the default constructor
and then assignment.
This reverts commit 7ab25ad020.
Reported by Brooks Moses <bmoses@google.com>
http://lists.gnu.org/archive/html/bison-patches/2018-02/msg00000.html
* data/lalr1.cc (YY_EXCEPTIONS): New.
Use it to disable try/catch clauses.
* doc/bison.texi (C++ Parser Interface): Document it.
* configure.ac (CXXFLAGS_NO_EXCEPTIONS): New.
* tests/atlocal.in: Receive it.
* tests/local.at (AT_FULL_COMPILE, AT_LANG_COMPILE):
Accept a new argument, extra compiler flags.
* tests/calc.at: Run the C++ calculator with exception support disabled.
Reported by Jannick.
http://lists.gnu.org/archive/html/bug-bison/2017-05/msg00001.html
"Amusingly" enough, we have the same problem with %defines when the
parser file name has backslashes or quotes: we generate #includes with
an incorrect C string.
* src/output.c (prepare_symbol_definitions): Escape properly the file
names before passing them to M4.
* data/bison.m4, data/lalr1.cc: Don't simply put the file name between
two quotes (that should have been strong enough a smell...), expect
the string to be properly quoted.
* tests/synclines.at: New tests to check this.
In 0931d14728 I removed too many
initializations from some ctors: some were not about base ctors, but
about member variables. In fact, more of them were missing to please
GCC 8.
While at it, generate more natural code for C++ without variant:
instead of
template <typename Base>
parser::basic_symbol<Base>::basic_symbol (const basic_symbol& other)
: Base (other)
, value ()
{
value = other.value
}
generate
template <typename Base>
parser::basic_symbol<Base>::basic_symbol (const basic_symbol& other)
: Base (other)
, value (other.value)
{}
* data/c++.m4 (basic_symbol::basic_symbol): Always initialize 'value',
it might be a POD without a ctor.
* data/lalr1.cc (stack_symbol_type::stack_symbol_type): Likewise.
* data/variant.hh (variant::variant): Default initialize the buffer too.
We currently generate copy constructors such as the following
one (taken from examples/variant.yy):
parser::stack_symbol_type::stack_symbol_type (const stack_symbol_type& that)
: super_type (that.state, that.location)
{
switch (that.type_get ())
{
case 3: // TEXT
case 8: // item
value.copy< ::std::string > (that.value);
break;
case 7: // list
value.copy< ::std::vector<std::string> > (that.value);
break;
case 4: // NUMBER
value.copy< int > (that.value);
break;
default:
break;
}
}
they are actually useless: we never need it.
* data/lalr1.cc: Don't generate the stack_symbol_type copy ctor.
For instance on test 99:
In file included from @@.cc:56:
@@.hh:409:26: error: definition of implicit copy constructor for
'stack_symbol_type' is deprecated because it
has a user-declared copy assignment operator
[-Werror,-Wdeprecated]
stack_symbol_type& operator= (const stack_symbol_type& that);
^
Reported by Derek Clegg.
https://lists.gnu.org/archive/html/bison-patches/2018-05/msg00036.html
* configure.ac (warn_tests): Add -Wdeprecated.
* data/lalr1.cc (stack_symbol_type): Add an explicit copy ctor.
We cannot rely on the explicit default implementation (`= default`)
as we support C++ 98.
At least GCC 7.3, with -O1 or -O2 (but not -O0 or -O3) generates
warnings with -Wnull-dereference when using yyformat: it fails to see
yyformat cannot be null.
Reported by Frank Heckenbach, https://savannah.gnu.org/patch/?9620.
* configure.ac: Use -Wnull-dereference if supported.
* data/glr.c, data/lalr1.cc, data/yacc.c: Define yyformat in such
a way that GCC cannot not see that yyformat is defined.
Using `default: abort();` also addresses the issue, but forces
the inclusion of `stdlib.h`, which we avoid.
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.
Currently lalr1.cc makes an out-of-bound access when trying to read @1
in rules with an empty rhs (i.e., when there is no @1) that raises an
error (YYERROR).
glr.c already gracefully handles this by using @$ as initial location
for the errors. Let's do that in yacc.c and lalr1.cc.
* data/lalr1.cc, data/yacc.c: Use @$ to initialize the error location.
* tests/actions.at: Check that case.
This style appears to be more traditional, at least in C++.
For instance in the standard, [facets.examples].
There are occurrences using "unsigned int" too though.
* data/lalr1.cc, data/location.cc, data/stack.hh: here.
