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.
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.
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.
"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.
Avoid duplicate warnings about %error-verbose, once for deprecation,
another for duplicate. Keep only the duplicate warning for the second
occurrence of %error-verbose.
This will help removal fixits.
* src/scan-gram.l (%error-verbose): Return as a PERCENT_ERROR_VERBOSE
token.
* src/parse-gram.y (do_error_verbose): New.
Use it.
* src/muscle-tab.c (muscle_percent_variable_update): Handle pseudo
variables such as %error-verbose.
Currently, on
%define parser_class_name "Parser"
%define parser_class_name "Parser"
%%
exp:;
we issue:
foo.y:1.9-25: warning: deprecated directive, use '%define api.parser.class {Parser}' [-Wdeprecated]
%define parser_class_name "Parser"
^~~~~~~~~~~~~~~~~
foo.y:2.9-25: warning: deprecated directive, use '%define api.parser.class {Parser}' [-Wdeprecated]
%define parser_class_name "Parser"
^~~~~~~~~~~~~~~~~
foo.y:2.9-25: error: %define variable 'api.parser.class' redefined
%define parser_class_name "Parser"
^~~~~~~~~~~~~~~~~
foo.y:1.9-25: previous definition
%define parser_class_name "Parser"
^~~~~~~~~~~~~~~~~
Let's get rid of the second warning about the deprecated variable
parser_class_name. This is noise, but it will also be a problem with
fixits for removing duplicates, as we will first generate the update,
and then it's too late to remove it: fixits do not edit the result of
previous fixits.
So generate this instead:
foo.y:1.1-34: warning: deprecated directive, use '%define api.parser.class {Parser}' [-Wdeprecated]
%define parser_class_name "Parser"
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
foo.y:2.1-34: error: %define variable 'api.parser.class' redefined
%define parser_class_name "Parser"
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
foo.y:1.1-34: previous definition
%define parser_class_name "Parser"
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* src/muscle-tab.c (muscle_percent_variable_update): Pass the warning
to the caller, instead of issuing it.
(muscle_percent_define_insert): Issue this warning only if we don't
have to complain about a duplicate definition.
* tests/input.at: Adjust expectations.
* src/parse-gram.y: Use the location of the whole definition to record
the location of a %define variable, instead of just the name of the
variable.
Adjust tests.
Introduce proper support for fixits, instead of just printing them on
demand.
* bootstrap.conf: We need gnulib's xlists.
* src/fixits.h, src/fixits.c: New.
* src/complain.c (deprecated_directive): Use fixits_register.
* src/main.c (main): Use fixits_free.
Currently the diagnostics for %name-prefix are not precise enough. In
particular, they does not show that braces must be used instead of
quotes.
Before:
foo.y:3.1-14: warning: deprecated directive, use '%define api.prefix' [-Wdeprecated]
%name-prefix = "foo"
^^^^^^^^^^^^^^
After:
foo.y:3.1-20: warning: deprecated directive, use '%define api.prefix {foo}' [-Wdeprecated]
%name-prefix = "foo"
^^^^^^^^^^^^^^^^^^^^
To do this we need the value passed to %name-prefix, so move the
warning from the scanner to the parser.
Accuracy will be very important for the forthcoming changes.
* src/parse-gram.y (do_name_prefix): New.
(PERCENT_NAME_PREFIX): Have a semantic value: the raw source, with
possibly underscores, equal sign, and spaces. This is used to provide
a more accurate message. It does not take comments into account,
but...
* src/scan-gram.l (%name-prefix): Delegate the warnings to the parser.
* tests/headers.at, tests/input.at: Adjust expectations.
* src/muscle-tab.c (muscle_percent_variable_update): Avoid allocating
memory when it is not needed, which should be most of the time (when
there's no update to perform).
Adjust callers.
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.
Suggested by David Barto
https://lists.gnu.org/archive/html/help-bison/2015-02/msg00004.html
and Victor Zverovich.
https://lists.gnu.org/archive/html/bison-patches/2018-10/msg00121.html
This is very easy to do, thanks to work by Bruno Haible in gnulib.
See "Supporting Relocation" in gnulib's documentation.
* bootstrap.conf: We need relocatable-prog and relocatable-script (for yacc).
* src/yacc.in: New.
* configure.ac, src/local.mk: Instantiate it.
* src/main.c, src/output.c (main, pkgdatadir): Use relocatable2.
* doc/bison.texi (FAQ): Document it.
