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.
Prompted by Rici Lake.
http://lists.gnu.org/archive/html/bug-bison/2018-10/msg00000.html
We have four classes of directives that declare symbols: %nterm,
%type, %token, and the family of %left etc. Currently not all of them
support the possibility to have several type tags (`<type>`), and not
all of them support the fact of not having any type tag at all
(%type). Let's unify this.
- %type
POSIX Yacc specifies that %type is for nonterminals only. However,
some Bison users want to use it for both tokens and nterms
(actually, Bison's own grammar does this in several places, e.g.,
CHAR). So it should accept char/string literals.
As a consequence cannot be used to declare tokens with their alias:
`%type foo "foo"` would be ambiguous (are we defining foo = "foo",
or are these two different symbols?)
POSIX specifies that it is OK to use %type without a type tag. I'm
not sure what it means, but we support it.
- %token
Accept token declarations with number and string literal:
(ID|CHAR) NUM? STRING?.
- %left, etc.
They cannot be the same as %token, because we accept to declare the
symbol with %token, and to then qualify its precedence with %left.
Then `%left foo "foo"` would also be ambiguous: foo="foo", or two
symbols.
They cannot be simply a list of identifiers, but POSIX Yacc says we
can declare token numbers here. I personally think this is a bad
idea, precedence management is tricky in itself and should not be
cluttered with token declaration issues.
We used to accept declaring a token number on a string literal here
(e.g., `%left "token" 1`). This is abnormal. Either the feature is
useful, and then it should be supported in %token, or it's useless
and we should not support it in corner cases.
- %nterm
Obviously cannot accept tokens, nor char/string literals. Does not
exist in POSIX Yacc, but since %type also works for terminals, it is
a nice option to have.
* src/parse-gram.y: Avoid relying on side effects. For instance, get
rid of current_type, rather, build the list of symbols and iterate
over it to assign the type.
It's not always possible/convenient. For instance, we still use
current_class.
Prefer "decl" to "def", since in the rest of the implementation we
actually "declare" symbols, we don't "define" them.
(token_decls, token_decls_for_prec, symbol_decls, nterm_decls): New.
Use them for %token, %left, %type and %nterm.
* src/symlist.h, src/symlist.c (symbol_list_type_set): New.
* tests/regression.at b/tests/regression.at
(Token number in precedence declaration): We no longer accept
to give a number to string literals.
After having spent quite some time on cleaning the handling of symbol
declarations in the grammar files, I believe we should keep it.
It looks like it's a duplicate of %type, but it is not. While POSIX
Yacc requires %type to apply only to nonterminal symbols, it appears
that both byacc and bison accept it for tokens too. And some
experienced users do actually expect this feature to group
symbols (terminal or not) by type ("On the other hand, it is generally
more useful IMHO to group terminals and non-terminals with the same
type tag together",
http://lists.gnu.org/archive/html/bug-bison/2018-10/msg00000.html).
Even Bison's own parser does this today (see CHAR).
Basically reverts 7928c3e6fb.
* src/scan-gram.l (%nterm): Dedeprecate, but issue a Wyacc warning.
* tests/input.at: Adjust expectations.
(Yacc warnings on symbols): New.
* src/symtab.c (symbol_class_set): Fix error introduced in
20b0746793.
I personally prefer 'non terminal', or 'non-terminal', but
'nonterminal' is the common spelling.
* data/glr.c, src/parse-gram.y, src/symtab.c, src/symtab.h,
* tests/input.at, doc/refcard.tex: here.
Currently our error messages include both "symbol redeclared" and
"symbol redefined", and they mean something different. This is
obscure, let's make this clearer.
I think the idea between 'definition' vs. 'declaration' is that in the
case of the nonterminals, the actual definition is its set of rules,
so %nterm would be about declaration. The case of %token is less
clear.
* src/symtab.c (complain_class_redefined): New.
(symbol_class_set): Use it.
Simplify the logic of this function to clearly skip its body when the
preconditions are not met.
* tests/input.at (Symbol class redefinition): New.
Revamping the handling of the symbols is the grammar is much more
delicate than I anticipated. Let's first move things around for
clarity.
* src/symtab.c (symbol_make_alias): Don't accept to alias
non-terminals.
(symbol_user_token_number_set): Don't accept user token numbers
for non-terminals.
Don't do anything in case of redefinition, instead of trying to
update. The flow is eaier to follow this way.
