In the following grammar, the 'exp' nonterminal is trivially useless.
So, of course, its rules are useless too.
%%
input: '0' | exp
exp: exp '+' exp | exp '-' exp | '(' exp ')'
Previously all the useless rules were reported, including those whose
left-hand side is the 'exp' nonterminal:
warning: 1 nonterminal useless in grammar [-Wother]
warning: 4 rules useless in grammar [-Wother]
2.14-16: warning: nonterminal useless in grammar: exp [-Wother]
input: '0' | exp
^^^
2.14-16: warning: rule useless in grammar [-Wother]
input: '0' | exp
^^^
! 3.6-16: warning: rule useless in grammar [-Wother]
! exp: exp '+' exp | exp '-' exp | '(' exp ')'
! ^^^^^^^^^^^
! 3.20-30: warning: rule useless in grammar [-Wother]
! exp: exp '+' exp | exp '-' exp | '(' exp ')'
! ^^^^^^^^^^^
! 3.34-44: warning: rule useless in grammar [-Wother]
! exp: exp '+' exp | exp '-' exp | '(' exp ')'
! ^^^^^^^^^^^
The interest of being so verbose is dubious. I suspect most of the
time nonterminals are not expected to be useless, so the user wants to
fix the nonterminal, not remove its rules. And even if the user
wanted to get rid of its rules, the position of these rules probably
does not help more that just having the name of the nonterminal.
This commit discard these messages, marked with '!', and keep the
others. In particular, we still report:
2.14-16: warning: rule useless in grammar [-Wother]
input: '0' | exp
^^^
All the useless rules (including the '!' ones) are still reported in
the reports (xml, text, etc.); only the diagnostics on stderr change.
* src/gram.c (grammar_rules_useless_report): Don't complain about
useless rules whose lhs is useless.
* src/reduce.h, src/reduce.c (reduce_nonterminal_useless_in_grammar):
Take a sym_content as argument.
Adjust callers.
* tests/reduce.at (Useless Rules, Underivable Rules, Reduced Automaton):
Adjust.
* origin/maint:
tests: split a large test case into several smaller ones
package: a bit of trouble shooting indications
doc: liby's main arms the internationalization
bison: avoid warnings from static code analysis
c++: fix the use of destructors when variants are enabled
style: tests: simplify the handling of some C++ tests
c++: symbols can be empty, so use it
c++: variants: don't leak the lookahead in error recovery
c++: provide a means to clear symbols
c++: clean up the handling of empty symbols
c++: comment and style changes
c++: variants: comparing addresses of typeid.name() is undefined
c++: locations: complete the API and fix comments
build: do not clean figure sources in make clean
* tests/conflicts.at (AT_CONSISTENT_ERRORS_CHECK): Move AT_SETUP/AT_CLEANUP
into it, so that we don't skip non Java tests following a test case in Java.
A static analysis tool reports that some callers of symbol_list_n_get
might get NULL and not handle it properly. This is not the case, yet
we can suppress this pattern.
Reported by Mike Sullivan.
<https://lists.gnu.org/archive/html/bug-bison/2013-12/msg00027.html>
* src/symlist.c (symbol_list_n_get): Actually it is never called
to return 0. Enforce this postcondition via aver.
(symbol_list_n_type_name_get): Simplify accordingly. In particular,
discards a (translated) useless error message.
* src/symlist.h: Adjust documentation.
* src/scan-code.l: Style change.
When using variants, destructors generate invalid code.
<http://lists.gnu.org/archive/html/bug-bison/2014-09/msg00005.html>
Reported by Michael Catanzaro.
* data/c++.m4 (~basic_symbol): b4_symbol_foreach works on yysym:
define it.
* tests/c++.at (Variants): Check it.
The previous patches ensure that symbols (symbol_type and
stack_symbol_type) can be empty, cleared, and their emptiness can be
checked. Therefore, yyempty, which codes whether yyla is empty or
not, is now useless.
In C skeletons (e.g., yacc.c), the fact that the lookahead is empty is
coded by "yychar = YYEMPTY", which is exactly what this patch
restores, since yychar/yytoken corresponds to yyla.type.
* data/lalr1.cc (yyempty): Remove.
Rather, depend on yyla.empty ().
During error recovery, when discarding the lookeahead, we don't
destroy it, which is caught by parse.assert assertions.
Reported by Antonio Silva Correia.
With an analysis and suggested patch from Michel d'Hooge.
<http://savannah.gnu.org/support/?108481>
* tests/c++.at (Variants): Strengthen the test to try syntax errors
with discarded lookahead.
The symbol destructor is currently the only means to clear a symbol.
Unfortunately during error recovery we might have to clear the
lookahead, which is a local variable (yyla) that has not yet reached
its end of scope.
Rather that duplicating the code to destroy a symbol, or rather than
destroying and recreating yyla, let's provide a means to clear a
symbol.
Reported by Antonio Silva Correia, with an analysis from Michel d'Hooge.
<http://savannah.gnu.org/support/?108481>
* data/c++.m4, data/lalr1.cc (basis_symbol::clear, by_state::clear)
(by_type::clear): New.
(basic_symbol::~basic_symbol): Use clear.
Instead of storing and comparing pointers to names of types, store
pointers to the typeids, and compares the typeids.
Reported by Thomas Jahns.
<http://lists.gnu.org/archive/html/bug-bison/2014-03/msg00001.html>
* data/variant.hh (yytname_): Replace with...
(yytypeid_): this.
There are no support for += between locations, and some comments are wrong.
Reported by Alexandre Duret-Lutz.
* data/location.cc: Fix.
* doc/bison.texi: Document.
* tests/c++.at: Check.
* origin/maint:
build: don't try to generate docs when cross-compiling
package: fix a reporter's name
%union: fix the support for named %union
package: bump to 2015
flex: don't trust YY_USER_INIT
yacc.c: fix broken union when api.value.type=union and %defines are used
doc: fix missing xref
gnulib: update
location: remove some ugly debugging code traces
build: use abort to pacify compiler errors
package: bump to 2014
doc: specify documentation encoding
Bison supports a union tag, for obscure reasons. But it does a poor
job at it, especially since Bison 3.0.
Reported by Stephen Cameron and Tobias Frost.
It did not ensure that the name was not given several times. An easy
way to do this is to make the %union tag be handled as a %define
variable, as they cannot be defined several times.
Since Bison 3.0, the synclines were wrongly placed, resulting in
invalid code. Addressing this issue, because of the way the union tag
was stored (as a code muscle), would have been tedious. Unless we
rather define the %union tag as a %percent variable, whose synclines
are easier to manipulate.
So replace the b4_union_name muscle by the api.value.union.name
%define variable, document, and check.
* data/bison.m4: Make sure that api.value.union.name has a keyword value.
* data/c++.m4: Make sure that api.value.union.name is not defined.
* data/c.m4 (b4_union_name): No longer use it, use api.value.union.name.
* doc/bison.texi (%define Summary): Document it.
* src/parse-gram.y (union_name): No longer define b4_uion_name, but
api.value.union.name.
* tests/input.at (Redefined %union name): New.
* tests/synclines.at (%union name syncline): New.
* tests/types.at: Check named %unions.
Reported by Rich Wilson.
* data/c.m4 (b4_symbol_type_register): Append to b4_union_members,
not b4_user_union_members.
The latter invokes the former, but it is the former which is reinitialized
to empty by b4_value_type_setup_union.
* tests/types.at: Check it.
This reveals another bug, this time in the case of glr.c parsers.
* data/glr.c: Generate the header file before the implementation file,
to be sure that the setup is run before what depends on it.
clang, with -DNDEBUG and -Werror fails on some functions that might
lack a return. This is because aver is just another assert, discarded
with -DNDEBUG. So use abort.
* src/muscle-tab.c, src/scan-skel.l: here.
This completes and fixes a728075710.
Reported by Valentin Tolmer.
Before it Bison used to put the properties of the symbols
(associativity, printer, etc.) in the 'symbol' structure. An
identifier-named token (FOO) and its string-named alias ("foo")
duplicated these properties, and symbol_check_alias_consistency()
checked that both had compatible properties and fused them, at the end
of the parsing of the grammar.
The commit a728075710 introduces a
sym_content structure that keeps all these properties, and ensures
that both aliases point to the same sym_content (instead of
duplicating). However, it removed symbol_check_alias_consistency,
which resulted in the non-fusion of *existing* properties:
%token FOO "foo"
%left FOO %left "foo"
was properly diagnosed as a redeclaration, but
%left FOO %left "foo"
%token FOO "foo"
was not, as the properties of FOO and "foo" were not checked before
fusion. It certainly also means that
%left "foo"
%token FOO "foo"
did not transfer properly the associativity to FOO.
The fix is simple: reintroduce symbol_check_alias_consistency (under a
better name, symbol_merge_properties) and call it where appropriate.
Also, that commit made USER_NUMBER_HAS_STRING_ALIAS useless, but left
it.
* src/symtab.h (USER_NUMBER_HAS_STRING_ALIAS): Remove, unused.
Adjust dependencies.
* src/symtab.c (symbol_merge_properties): New, based on the former
symbol_check_alias_consistency.
* tests/input.at: Re-enable tests that we now pass.
* origin/maint:
package: install the examples
package: install README and the like in docdir
diagnostics: fix the order of multiple declarations reports
symbol: provide an easy means to compare them in source order
Conflicts:
src/symtab.c
tests/input.at
* tests/input.at: Comment out a test that master currently does not
pass (because of a728075710).
Currently, we do not install the various examples extracted from the
documentation. Let's do it, as they are useful starting points.
* configure.ac: When --enable-gcc-warnings is set, enable ENABLE_GCC_WARNINGS.
* examples/extexi: No longer issue synclines by default.
* examples/local.mk: Except if ENABLE_GCC_WARNINGS.
* examples/calc++/local.mk, examples/mfcalc/local.mk,
* examples/rpcalc/local.mk: Install the example files.
* origin/maint: (43 commits)
maint: post-release administrivia
version 3.0.2
gnulib: update
output: do not generate source files when late errors are caught
output: record what generated files are source or report files
output: do not generate source files when early errors are caught
xml: also use "%empty" with html output
style: formatting changes
xml: also display %empty for empty right-hand sides
reports: display %empty in the generated pointed-rules
news: YYERROR vs variants
style: scope reduction in lalr.cc
lalr1.cc: formatting changes
lalr1.cc: fix the support of YYERROR with variants
tests: check $$'s destruction with variant, YYERROR, and no error recovery
tests: simplify useless obfuscation
skeletons: use better names when computing a "goto"
maint: post-release administrivia
version 3.0.1
aver: it is no longer "protected against NDEBUG"
...
Conflicts:
data/glr.c
Reported by Alexandre Duret-Lutz as "second problem" in:
http://lists.gnu.org/archive/html/bug-bison/2013-09/msg00015.html
* bootstrap.conf: We need the "unlink" module.
* src/files.h, src/files.c (unlink_generated_sources): New.
* src/output.c: Use it.
* tests/output.at: Check the case of late errors.
* src/files.h, src/files.c (output_file_name_check): Take an additional
argument to record whether a file is a source or report file.
* src/files.c (generated_file): New.
(file_names, file_names_count): Replace with...
(generated_files, generated_files_size): these.
* src/scan-skel.l: Adjust.
Reported by Alexandre Duret-Lutz as "second problem" in:
http://lists.gnu.org/archive/html/bug-bison/2013-09/msg00015.html
One problem is that some errors are caught early, before the
generation of output files, while others can only be detected
afterwards (since, for instance, skeletons can raise errors
themselves).
This will be addressed in two steps: early errors do not generate
source files at all, while later errors will remove the files that
have already been generated.
* src/scan-skel.l (yyout): Open to /dev/null when there are errors.
* tests/output.at (AT_CHECK_FILES): Factored out of...
(AT_CHECK_OUTPUT): this.
Fuse the "SHELLIO" argument in the "FLAGS" one.
Use $5 to denote the expected exit status.
Add a test case for early errors.
When variant are enabled, the yylhs variable (the left-hand side of
the rule being reduced, i.e. $$ and @$) is explicitly destroyed when
YYERROR is called. This is because before running the user code, $$
is initialized, so that the user can properly use it.
However, when quitting yyparse, yylhs is also reclaimed by the C++
compiler: the variable goes out of scope.
Instead of trying to be too smart, let the compiler do its job: reduce
the scope of yylhs to exactly the reduction. This way, whatever the
type of scope exit (regular, exception, return, goto...) this variable
will be properly reclaimed.
Reported by Paolo Simone Gasparello.
<http://lists.gnu.org/archive/html/bug-bison/2013-10/msg00003.html>
* data/lalr1.cc (yyparse): Reduce the scope of yylhs.
* tests/c++.at: We now pass this test.
When variant are enabled, the yylhs variable (the left-hand side of
the rule being reduced, i.e. $$ and @$) is explicitly destroyed when
YYERROR is called. This is because before running the user code, $$
is initialized, so that the user can properly use it.
However, when quitting yyparse, yylhs is also reclaimed by the C++
compiler: the variable goes out of scope.
This was not detected by the test suite because (i) the Object tracker
was too weak, and (ii) the problem does not show when there is error
recovery.
Reported by Paolo Simone Gasparello.
<http://lists.gnu.org/archive/html/bug-bison/2013-10/msg00003.html>
* tests/c++.at (Exception safety): Improve the objects logger to make
sure that we never destroy twice an object.
Also track copy-constructors.
Use a set instead of a list.
Display the logs before running the function body, this is more
useful in case of failure.
Generalize to track with and without error recovery.
* data/glr.c (yyLRgotoState): Name the symbol argument yysym, instead
of yylhs.
* data/lalr1.cc (yy_lr_goto_state_): Likewise.
* data/lalr1.java (yy_lr_goto_state_): New, modeled after the previous
two routines.
Use it.
Apply the same rules for aver as for assert: no side effects,
especially not important ones.
* src/AnnotationList.c, src/muscle-tab.c: Adjust aver uses to resist
to -DNDEBUG.
Building C++ parsers with -Wsuggest-attribute=const and
-Wsuggest-attribute=noreturn triggers warning in generated code.
* data/lalr1.cc: Call b4_attribute_define.
(debug_stream, debug_level): Flag as pure.
* tests/headers.at (Several parsers): There are now more YY macros
that "leak".
Some tests now fail when compiled with G++ 4.3 or 4.4 on MacPorts.
* tests/local.at (AT_SKIP_IF_EXCEPTION_SUPPORT_IS_POOR): New.
* tests/c++.at (Exception safety): Use it.
* configure.ac (ENABLE_YACC): New conditional.
(YACC_SCRIPT, YACC_LIBRARY): Remove.
* lib/local.mk, src/local.mk: Use the former instead of the latter.
* doc/local.mk: Use ENABLE_YACC to avoid installing yacc.1.
Currently "-Werror -Wno-error=foo" still turns "foo" warnings into errors.
Reported by Alexandre Duret-Lutz.
See http://lists.gnu.org/archive/html/bug-bison/2013-09/msg00015.html.
* src/complain.c (errority, errority_flag): New.
(complain_init): Initialize the latter.
(warning_argmatch): Extract the loop iterating on the flag's bits.
Set and unset errority_flag here.
(warnings_argmatch): -Wno-error is not the same as -Wno-error=everything:
we must remember if category foo was explicitly turned in an error/warning
via -W(no-)error=foo.
(warning_severity): Use errority_flag.
* tests/input.at (Symbols): Just check --yacc, not -Wyacc, that's the
job of tests on -W.
(-Werror is not affected by -Wnone and -Wall): Rename as...
(-Werror combinations): this.
Tests more combinations of -W, -W(no-)error, and -W(no-)error=foo.
* tests/local.at (AT_BISON_CHECK_WARNINGS): Don't expect -Werror
to turn runs that issue warnings into runs with errors, as the
warnings might be enforced as warnings by -Wno-error=foo, in which
case -Werror does not change anything.
* doc/bison.texi (Bison Options): Try to be clearer about how
-W(no-)error and -W(no-)error=foo interact.
* origin/maint:
glr: more assertions
glr: shorten scopes
glr: formatting changes
glr: better use of tracing macros
examples: improve the output of the "variant" example
variant: remove useless assertion
tests: remove stray debugging traces
tests: do not use grep -q
build: don't require flex for ordinary builds
maint: update .gitignore
build: port to pre-5.8.7 perl
tests: minor change to make it easier to test other skeletons
uniqstr: fix assertion
The commit which introduces yyresolveLocations (commit
8710fc41aa) saves and restores the
look-ahead (type, value and location) for no clear reason. This
appears to be useless.
* data/glr.c (yyresolveLocations): Don't save/restore the current
look-ahead to call YYLLOC_DEFAULT.
Minor style changes.
We don't ship the *.txt files that are used to build the info
file.
Reported by Colin Daley.
* doc/figs/example.txt: New.
* doc/local.mk (bison.info): Depend on the txt files.
And ship them.
* tests/c++.at (Exception safety): In variant mode $$ is an instance
of Object. Assigning YY_NULL in C++98 is incorrect, but behaves ok,
as it assigns YY_NULL=0 using Object::operator= (char v). It is wrong
in C++11 as there is operator for "$$ = nullptr".
Again some issues with the fact that yylval is reported by GCC as
possibly not initialized in some cases. Here, the case at hand is the
%destructor.
I am still not convinced that it is worth going all the trouble of
using pragmas to disable temporarily some warnings, instead of just
initializing the looking symbol once for all, but that's what Paul
voted for, see
<http://lists.gnu.org/archive/html/bison-patches/2012-10/msg00050.html>.
* data/c.m4 (b4_attribute_define): Define
YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN, YY_IGNORE_MAYBE_UNINITIALIZED_END,
YY_INITIAL_VALUE here, as we will need them in the generation of the
destructor function, which is defined in yacc.c before yyparse, which
was in charge of defining these macros.
* data/yacc.c (b4_declare_scanner_communication_variables): Simplify:
trying to factor the definitions of the case pure and impure is
too complex.
Actually, it is not even clear that this macro should really exist,
as even the calls are complex.
Be careful not to issue a lone ";", as this is a statement, and C90
forbids declarations after statements ; so write
"YY_INITIAL_VALUE(Decl;)", not "YY_INITIAL_VALUE(Decl);".
There are possible conflicts between gnulib replacement functions (in
<stdio.h>) and their C++ wrappers (in <stream>). Trying to address
these in configure seems too hard, and I don't know how to fix the issue
in gnulib. Cowardly avoid the problem by skipping C++ tests when this
happens.
Reported by Stefano Lattarini.
http://lists.gnu.org/archive/html/bug-bison/2013-06/msg00001.html
* tests/atlocal.in (BISON_CXX_WORKS): Also set it to "skip" if we can't
compile a simple program using <stream>.
* tests/local.at: Comment changes.
Akim Demaille