Reported by Derek Clegg
http://lists.gnu.org/archive/html/bug-bison/2019-01/msg00021.html
aux/parser-internal.h:429:12: error: 'syntax_error' has no out-of-line virtual
method definitions; its vtable will be emitted in every translation unit
[-Werror,-Wweak-vtables]
struct syntax_error : std::runtime_error
To avoid this warning, we need syntax_error to have a virtual function
defined in a compilation unit. Let it be the destructor. To comply
with C++98, this dtor should be 'throw()'. Merely making YY_NOEXCEPT
be 'throw()' in C++98 triggers
errors (http://lists.gnu.org/archive/html/bug-bison/2019-01/msg00022.html),
so let's introduce YY_NOTHROW and flag only ~syntax_error with it.
Also, since we now have an explicit dtor, we need to provide an copy
ctor.
* configure.ac (warn_cxx): Add -Wweak-vtables.
* data/skeletons/c++.m4 (YY_NOTHROW): New.
(syntax_error): Declare the dtor, and define the copy ctor.
* data/skeletons/glr.cc, data/skeletons/lalr1.cc (~syntax_error):
Define.
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.
The previous name was historical and inconsistent.
* src/muscle-tab.c (define_directive): Use the proper value passing
syntax, based on the muscle kind.
(muscle_percent_variable_update): Use the right value passing syntax.
Migrate from parser_class_name to api.parser.class.
* data/skeletons: Migrate from parser_class_name to api.parser.class.
* doc/bison.texi (%define Summary): Document both parser_class_name
and api.parser.class.
Promote the latter over the former.
