Since Bison 3.3, semantic values in rule actions (i.e., '$...') are
passed to the m4 backend as the symbol number. Unfortunately, when
there are unused symbols, the symbols are renumbered _after_ the
numbers were used in the rule actions. As a result, the evaluation of
the skeleton failed because it used non existing symbol numbers.
Which is the happy scenario: we could use numbers of other existing
symbols...
Reported by Balázs Scheidler.
http://lists.gnu.org/archive/html/bug-bison/2019-01/msg00044.html
Translating the rule actions after the symbol renumbering moves too
many parts in bison. Relying on the symbol identifiers is more
troublesome than it might first seem: some don't have an
identifier (tokens with only a literal string), some might have a
complex one (tokens with a literal string with characters special for
M4). Well, these are tokens, but nterms also have issues: "dummy"
nterms (for midrule actions) are named $@32 etc. which is risky for
M4.
Instead, let's simply give M4 the mapping between the old numbers and
the new ones. To avoid confusion between old and new numbers, always
emit pre-renumbering numbers as "orig NUM".
* data/README: Give details about "orig NUM".
* data/skeletons/bison.m4 (__b4_symbol, _b4_symbol): Resolve the
"orig NUM".
* src/output.c (prepare_symbol_definitions): Pass nterm_map to m4.
* src/reduce.h, src/reduce.c (nterm_map): Extract it from
nonterminals_reduce, to make it public.
(reduce_free): Free it.
* src/scan-code.l (handle_action_dollar): When referring to a nterm,
use "orig NUM".
* tests/reduce.at (Useless Parts): New, based Balázs Scheidler's
report.
It is inconvenient that we also generate the output files when we
update the grammar file, and it's somewhat unexpected. Let's not do
that.
* src/main.c (main): Skip generation when --update is passed.
* src/getargs.c (usage): Update the help message.
* doc/bison.texi (Bison Options): Likewise.
* tests/input.at: Check that we don't generate the output.
After all, this is clearly harmless.
* src/muscle-tab.c (muscle_percent_define_insert): Let equal
definitions of a %define variable be only a warning.
Adjust test cases.
* tests/input.at ("%define" backward compatibility): Don't define
twice "api.namespace", so that we don't get an error, which stops the
process too soon to see an error about the value given to
'lr.keep-unreachable-state'.
Don't repeat the name of the warning in the sub messages. E.g.,
remove the second "[-Wother]" in the following message
foo.y:2.1-27: warning: %define variable 'parse.error' redefined [-Wother]
%define parse.error verbose
^~~~~~~~~~~~~~~~~~~~~~~~~~~
foo.y:1.1-27: previous definition [-Wother]
%define parse.error verbose
^~~~~~~~~~~~~~~~~~~~~~~~~~~
* src/complain.c (error_message): Don't print the warning type when
it's indented.
Adjust test cases.
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.
Some reported by syntax-check.
* po/POTFILES.in: Add fixits.cc.
* src/muscle-tab.c: Don't cast for free.
* src/files.c: Reduce scopes.
* cfg.mk: We need the cast for free in muscle_percent_define_insert.
* doc/bison.texi: Use @kbd where appropriate.
Update ^~~~ marks for caret-errors.
* build-aux/cross-options.pl: Do not add quotes to %define's argument.
"handle_" is the prefix used in scan-code.l for instance.
* src/parse-gram.y (do_error_verbose, do_name_prefix, do_require)
(do_skeleton, do_yacc):
Rename as...
(handle_error_verbose, handle_name_prefix, handle_require)
(handle_skeleton, handle_yacc):
these.
We should use -ffixit and --update to clean files with duplicate
directives. And we should complain only once about duplicate obsolete
directives: keep only the "duplicate" warning. Let's start with %yacc.
For instance on:
%fixed-output_files
%fixed-output-files
%yacc
%%
exp:
This run of bison:
$ bison /tmp/foo.y -u
foo.y:1.1-19: warning: deprecated directive, use '%fixed-output-files' [-Wdeprecated]
%fixed-output_files
^~~~~~~~~~~~~~~~~~~
foo.y:2.1-19: warning: duplicate directive [-Wother]
%fixed-output-files
^~~~~~~~~~~~~~~~~~~
foo.y:1.1-19: previous declaration
%fixed-output_files
^~~~~~~~~~~~~~~~~~~
foo.y:3.1-5: warning: duplicate directive [-Wother]
%yacc
^~~~~
foo.y:1.1-19: previous declaration
%fixed-output_files
^~~~~~~~~~~~~~~~~~~
bison: file 'foo.y' was updated (backup: 'foo.y~')
gives:
%fixed-output-files
%%
exp:
* src/location.h, src/location.c (location_empty): New.
* src/complain.h, src/complain.c (duplicate_directive): New.
* src/getargs.h, src/getargs.c (yacc_flag): Instead of a Boolean, be
the location of the definition.
Update dependencies.
* src/scan-gram.l (%yacc, %fixed-output-files): Move the handling of
its warnings to...
* src/parse-gram.y (do_yacc): This new function.
* tests/input.at (Deprecated Directives): Adjust expectations.
* src/fixits.h, src/fixits.c (fixits_empty): New.
* src/complain.c (deprecated_directive): Register the Wdeprecated
fixits only if -Wdeprecated was enabled, so that we don't apply
updates if the user didn't ask for them.
* src/main.c (main): If there were fixits, issue a warning suggesting
running with --update.
Free uniqstrs after the fixits, since the latter use the former.
* tests/headers.at, tests/input.at: Update expectations.
* src/fixits.c (fixits_run): If erase the content of a line, also
erase the following \n.
* tests/input.at (Deprecated directives): Update expectations.
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.
Reported by Derek Clegg.
http://lists.gnu.org/archive/html/bug-bison/2019-01/msg00006.html
Clang does not like this:
template <typename D>
struct basic_symbol : D
{
basic_symbol();
};
struct by_type {};
struct symbol_type : basic_symbol<by_type>
{
symbol_type(){}
};
It gives:
$ clang++-mp-7.0 -Wundefined-func-template foo.cc -c
foo.cc:11:3: warning: instantiation of function 'basic_symbol<by_type>::basic_symbol'
required here, but no definition is available [-Wundefined-func-template]
symbol_type(){}
^
foo.cc:4:3: note: forward declaration of template entity is here
basic_symbol();
^
foo.cc:11:3: note: add an explicit instantiation declaration to suppress this warning
if 'basic_symbol<by_type>::basic_symbol' is explicitly instantiated in
another translation unit
symbol_type(){}
^
1 warning generated.
The same applies for the basic_symbol's destructor and `clear()`.
* configure.ac (warn_cxx): Add -Wundefined-func-template.
This triggered one failure in the test suite:
* tests/headers.at (Sane headers): here, where we check that we can
compile the generated headers in other compilation units than the
parser's.
Add a variant type to make sure that basic_symbol and symbol_type are
properly generated in this case.
* data/skeletons/c++.m4 (basic_symbol): Inline the definitions of the
destructor and of `clear` in the class definition.
