440-453 and 685 failed with GCC 12.1:
```
test.cc:1814:21: required from here
/opt/local/include/gcc12/c++/bits/stl_construct.h:95:14: error: noexcept-expression evaluates to 'false' because of a call to '{anonymous}::glr_stack_item::glr_stack_item(bool)' [-Werror=noexcept]
95 | noexcept(noexcept(::new((void*)0) _Tp(std::declval<_Args>()...)))
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
test.cc:1486:5: note: but '{anonymous}::glr_stack_item::glr_stack_item(bool)' does not throw; perhaps it should be declared 'noexcept'
1486 | glr_stack_item (bool state = true)
| ^~~~~~~~~~~~~~
```
Reported by Paul Eggert.
<https://lists.gnu.org/r/bison-patches/2022-07/msg00008.html>
* data/skeletons/glr2.cc (glr_state, glr_stack_item): Declare the
default ctors noexcept.
Suggested by Don Macpherson.
<https://github.com/akimd/bison/issues/80>
* data/skeletons/c++.m4, data/skeletons/glr2.cc,
* data/skeletons/lalr1.cc, data/skeletons/stack.hh: Use YY_NOEXCEPT
where it helps constructors.
* data/skeletons/glr2.cc (semantic_option): Simplify the rule-based
constructor. This shows that it should be easy to use a symbol_kind,
instead of the kind/value/location triple.
I regret that %destructor and %printer give access to the %parse-param
in lalr1.cc, since that prevents them from being implemented as a
simple destructor and operator<<. Let's not repeat the mistake in
glr2.cc. In addition, fixes a name conflict we have currently in
tests 566 568 570 657:
calc.cc:1395:85: error: declaration shadows a field of 'calc::parser' [-Werror,-Wshadow]
void glr_state::destroy (char const* yymsg, calc::parser& yyparser, semantic_value *result, int *count, int *nerrs)
^
calc.hh:441:21: note: previous declaration is here
semantic_value *result;
^
With this commit, the whole test suite passes for glr2.cc.
* data/skeletons/glr2.cc (glr_state::destroy): Don't take the user
arguments.
Fixes several calc tests.
Tests 566 568 570 657 still fail because of a name clash when using
%parse-param:
calc.cc:1395:85: error: declaration shadows a field of 'calc::parser' [-Werror,-Wshadow]
void glr_state::destroy (char const* yymsg, calc::parser& yyparser, semantic_value *result, int *count, int *nerrs)
^
calc.hh:441:21: note: previous declaration is here
semantic_value *result;
^
* data/skeletons/glr2.cc: Fix indentation/trailing spaces.
In order to be able to link several glr2.cc parser together, we cannot
have glr_stack and glr_state be in no namespace. Putting them in the
unnamed namespace is not doable, since we need to fwd declare them in
the parser. Putting them in the specified namespace is not enough
either, since some users would like to be able to put several parsers
in the same name, only differing by the class name.
* data/skeletons/glr2.cc (glr_state, glr_stack): Move into yy::parser.
If we link several glr2.cc parsers together, we get linking failures
because of duplicate symbols.
* data/skeletons/glr2.cc (semantic_option::indexIn)
(semantic_option::next): Remove the useless overloads.
We don't need them in the header file.
* data/skeletons/glr2.cc (YY_EXCEPTIONS): Define only in the
implementation file.
* tests/headers.at (Several Parsers): Also check glr2.cc.
Currently glr2.cc uses three variables/struct members to denote the
symbols' kind (or state), value and location. lalr1.cc has two types
for "complete" symbols: symbol_type and stack_symbol_type. Let's use
that model in glr2.cc too.
For a start use yyla (a symbol_type) to denote the lookahead, instead
of the triple yytoken, yylval and yylloc. This will make easier the
introduction of the "context" subclass, used in parse.error=custom.
It simplifies the code in several places. For instance from:
symbol_kind_type yytoken_current = this->yytoken;]b4_variant_if([[
value_type yylval_current;
]b4_symbol_variant([this->yytoken],
[yylval_current], [move], [this->yylval])], [[
value_type yylval_current = this->yylval;]])[]b4_locations_if([
location_type yylloc_current = this->yylloc;])[
to:
symbol_type yyla_current = std::move (this->yyla);
* data/skeletons/glr2.cc (yytoken, yylval, yylloc): Replace by...
(yyla): this.
Adjust all dependencies.
(yyloc_default): Remove, unused.
* tests/c++.at, tests/glr-regression.at, tests/types.at: C++11 is
required for glr2.cc.
Adjust to changes in glr2.cc.
* data/skeletons/c++.m4: Don't define obsolete identifiers in the case
of glr2.cc. Let's not start with technical debt.
* data/skeletons/glr2.cc, data/skeletons/lalr1.cc,
* data/skeletons/variant.hh: Use token_kind_type, not token_type.
* tests/c++.at, tests/local.at: Use value_type, not semantic_type.
Reported by Dagobert Michelsen.
https://lists.gnu.org/r/bug-bison/2021-08/msg00006.html
* m4/bison-cxx-std.m4 (_BISON_CXXSTD_98_snippet): We don't need
vector::data, it was only for glr2.cc, which is C++11 anyway.
(_BISON_CXXSTD_11_snippet): We need vector::data and std::swap on
arrays.
* m4/cxx.m4 (BISON_TEST_FOR_WORKING_CXX_COMPILER): We don't need
vector::data.
* tests/local.at (AT_COMPILE_CXX): Skip when glr2.cc and no support
for C++11.
It is very helpful to be able to look at the locations in the debug
traces, let's provide the users with (i) a means to do that for their
location types, and (ii) a public macro to print locations when debug
traces are enabled.
* data/skeletons/c.m4 (b4_yy_location_print_define): Rename as...
(b4_yylocation_print_define): this.
Define YYLOCATION_PRINT instead of YY_LOCATION_PRINT.
Ensure backward compatibility for those who might have defined/used
YY_LOCATION_PRINT in spite the warnings.
Adjust dependencies.
* data/skeletons/glr2.cc: We don't use YYLOCATION_PRINT here.
* data/skeletons/glr2.cc, data/skeletons/lalr1.cc (b4_lex): Don't
refer to YYSTYPE, but to value_type.
Note that this is "symbolic" in the sense that these values are never
used by b4_function_call.
Currently glr2.cc does not use 'symbol's everywhere, in various places
it also uses yykind, yyval and yyloc "by hand". So we need two
different calls for user-defined constructors: once for ~symbol,
another for yy_destroy_. Both need to call the user destructors with
different calling conventions.
* data/skeletons/glr2.cc (b4_symbol_action): Rename as...
(b4_symbol_action_for_yyval): this.
(b4_symbol_action): New, taken from lalr1.cc.
(yy_destroy_, yy_symbol_value_print_): Use b4_symbol_action_for_yyval.
I am not aware of people subclassing the parser class, and I fail to
see how this could be useful. Rather than leaving a badly baked
feature (as in glr.cc currently), let's not support it at all, until
someone comes and explains why and how it would be useful.
* data/skeletons/glr2.cc (parser): We need no virtual function members.
It's on purpose that I keep the `this->` now. We'll see later if we
want to remove them.
* data/skeletons/glr2.cc (yygetToken): Move into...
(glr_stack::yyget_token): this.
(b4_lex): Adjust.
Currently we have two classes that actually should be fused together:
parser and glr_stack. Both carry part of the parsing: (i) parser
contains `parse`, which is the top-level of the parsing process, it
uses yygetToken, etc., and (ii) glr_stack takes care of all the
details (dealing with the stack), and also calls yygetToken.
However if we fuse them together, we would get a large parser class,
in the header file. So it is probably better to split this large
class using the pimpl idiom. But then it appears that glr_stack is
very close from being the impl of parser.
Let's improve this.
For a start...
* data/skeletons/glr2.cc (parser::parse): Move to...
(glr_stack::parse): here.
(parser::parse): Use it.
* data/skeletons/glr2.cc: We no longer play dirty tricks with
parse-params, remove the now useless dance around them.
We now have genuine objects for locations, leave the initial action
alone.
* data/skeletons/glr2.cc: Add support for api.token.constructor.
* examples/c++/glr/c++-types.yy: Use it.
* examples/c++/glr/c++-types.test: Adjust expectations for error
messages.
* data/skeletons/c++.m4 (b4_yytranslate_define): Use static_cast
rather than the YY_CAST macro.
Avoids the need to define YY_CAST in the header.
* data/skeletons/glr2.cc: Fix calls to b4_shared_declarations: pass
the type of file we are in.
Don't define YYTRANSLATE.
(parser::yytranslate_): New, as in lalr1.cc.
Adjust to use it.
* tests/glr-regression.at: Adjust.
Instead of tracking the lookahead with yychar, use yytoken. This is
consistent with lalr1.cc, saves us from calls to YYTRANSLATE (except
when calling yylex), and makes it easier to migrate to using
symbol_type.
* data/skeletons/glr2.cc: Replace all uses of `int yychar` with
`symbol_kind_type yytoken`.
(yygetToken): Don't take/return the lookahead's token-kind and
symbol-kind, just work directly on yystack's `yytoken` member.
* tests/glr-regression.at (AT_PRINT_LOOKAHEAD_DECLARE)
(AT_PRINT_LOOKAHEAD_DEFINE): New.
Adjust to the fact that we have yytoken, not yychar, in glr2.cc.
* data/skeletons/glr2.cc (b4_symbol_action): New, so that we use
`yyval` and `yyloc` rather than the `yyvaluep` and `yylocationp`
pointers.
(yy_symbol_value_print_, yy_symbol_print_, yy_destroy_): Use
references rather than pointers.
Drop support for the undocumented, obsolete, `yyoutput` variable.
Adjust callers.
(glr_state::destroy): Don't use yy_symbol_print_ when we don't have a
symbol. Rather, write dedicated code.
(Bison) Variants are extremely picky, which makes them both
annoying (lots of micro-details must be taken care of) and
precious (all the micro-details must be taken care of, in particular
object lifetime).
So (i) each time a semantic value is stored, it must be stored in a
place that exists, and (ii) each time a semantic value is discarded,
its place must have been emptied.
Example of (i)
- new (&yys.value ()) value_type (s->value ());
+ {]b4_variant_if([[
+ new (&yys.value ()) value_type ();
+ ]b4_symbol_variant([yy_accessing_symbol (s->yylrState)],
+ [yys.value ()], [copy], [s->value ()])], [[
+ new (&yys.value ()) value_type (s->value ());]])[
+ }
Example of (ii)
yyparser.yy_destroy_ ("Error: discarding",
- yytoken, &yylval]b4_locations_if([, &yylloc])[);
+ yytoken, &yylval]b4_locations_if([, &yylloc])[);]b4_variant_if([[
+ // Value type destructor.
+ ]b4_symbol_variant([[YYTRANSLATE (this->yychar)]], [[yylval]], [[template destroy]])])[
this->yychar = ]b4_namespace_ref[::]b4_parser_class[::token::]b4_symbol(empty, id)[;
However, in some places we must not be "pure". In particular:
glr_stack_item (const glr_stack_item& other) YY_NOEXCEPT YY_NOTHROW
: is_state_ (other.is_state_)
{
std::memcpy (raw_, other.raw_, union_size);
}
still must use memcpy, because the constructor would change pred, and
it must not. This constructor is used only when resizing the stack,
in which case pred (which is relative) must not be "adjusted".
The result works, but is messy. Its verbosity comes from at least two
factors:
- we don't have support for complete symbols (binding kind, value and
location), and we should at least try to have it. That simplified
lalr1.cc a lot.
- I have not tried to be smart and use 'move' when possible. As a
consequence many places have 'copy' and then 'destroy'. That kind
of clean up can be done once everything appears to be solid.
* data/skeletons/glr2.cc: Be more rigorous in object lifetime.
In particular, don't forget to discard the lookahead when we're done
with it.
Call variant routines where needed.
Deal with plenty of details.
(b4_call_merger): Add support for variants.
Use references in mergers, rather than pointers.
* examples/c++/glr/c++-types.yy: Exercise variants.
This macro is not exposed to users, make start it with 'YY_'.
* data/skeletons/bison.m4, data/skeletons/c.m4, data/skeletons/glr.c,
* data/skeletons/glr.cc, data/skeletons/glr2.cc, data/skeletons/lalr1.cc,
* src/parse-gram.c, tests/actions.at, tests/c++.at, tests/headers.at,
* tests/local.at (YYUSE): Rename as...
(YY_USE): this.
