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.
useful ones and add a "usefulness" attribute. Discussed starting at
<http://lists.gnu.org/archive/html/bison-patches/2007-09/msg00017.html>.
* src/gram.c (grammar_rules_partial_print_xml): Remove.
(grammar_rules_print_xml): Print all rules instead of just those
useful in the grammar, and add a "usefulness" attribute.
* src/gram.h (grammar_rules_partial_print_xml): Remove prototype.
* src/print-xml.c (print_rules_useless_in_parser): Remove.
(print_grammar): Print all nonterminals instead of just useful ones,
and add a "usefulness" attribute to nonterminals and terminals.
(print_xml): Don't print a separate "reductions" or
"rules-useless-in-parser" element.
* src/reduce.c (reduce_output): Use reduce_token_unused_in_grammar.
(reduce_xml): Remove.
(reduce_token_unused_in_grammar): New.
(reduce_nonterminal_useless_in_grammar): New.
* src/reduce.h (reduce_xml): Remove prototype.
(reduce_token_unused_in_grammar): Add prototype.
(reduce_nonterminal_useless_in_grammar): Add prototype.
* data/xslt/xml2text.xsl: Update for XML changes.
* data/xslt/xml2xhtml.xsl: Update for XML changes.
* tests/reduce.at (Useless Terminals): Update output.
(Useless Rules): Update output.
(Reduced Automaton): Update output.
Say "Terminals unused in grammar" instead of "Unused terminals".
* NEWS (2.3a+): Update.
* doc/bison.texinfo (Understanding): Update example output.
* src/reduce.c (reduce_output): Implement.
* data/xslt/xml2text.xsl: Implement.
* data/xslt/xml2xhtml.xsl: Implement.
elsewhere.
* src/print-xml.c: Prefer "const" after types; that's more consistent.
(xml_printf): Indent just 1 space for level.
(e_char, xlate_char): Remove.
(xml_escape_string): Rewrite to avoid undefined behavior (used
storage that was freed from the stack).
(xml_escape_n): Don't bother checking for subscript error.
2007-09-21 Wojciech Polak <polak@gnu.org>
Add support for an -x option to generate an XML report.
It is not documented yet.
* src/print-xml.c: New file.
* src/print-xml.h: Likewise.
* lib/timevar.def (TV_XML): New var.
* src/Makefile.am (bison_SOURCES): Add print-xml.c, print-xml.h.
* src/conflicts.c: Include print-xml.h.
(solved_conflicts_xml_obstack): New var.
(log_resolution, conflicts_solve, conflicts_free):
Add support for XML report.
(conflicts_output_val): New function.
* src/conflicts.h (conflicts_output_val): New decl.
* src/files.c (spec_xml_file): New var.
(compute_output_file_names, output_file_names_free): Add XML support.
* src/files.h (spec_xml_file): New decl.
* src/getargs.c (xml_flag): New var.
(usage, short_options, long_options, getargs): Add XML support.
* src/getargs.h (xml_flag): New decl.
* src/gram.c: Include print-xml.h.
(rule_lhs_print_xml, rule_rhs_print_xml):
(grammar_rules_partial_print_xml, grammar_rules_print_xml):
New functions.
* src/gram.h: Declare external ones.
* src/main.c: Include print-xml.h.
(main): Add XML support.
* src/reduce.c: Include print-xml.h.
(reduce_xml): New function.
* src/reduce.h: Declare it.
* src/state.c: Include print-xml.h.
(state_new): Add XML support.
(state_rule_lookahead_tokens_print_xml): New function.
* src/state.h: Declare it.
(struct state): New member solved_conflicts_xml.
* src/symtab.c (symbol_class_get_string): New function.
* src/symtab.h: Declare it.
2007-09-21 Paul Eggert <eggert@cs.ucla.edu>
`destroyed'), we now sometimes examine them, and store information
related to them. Hence we need to know their number, and adjust
memory allocations.
* src/reduce.c, src/reduce.h (nuseless_nonterminals): No longer
static.
* src/LR0.c (allocate_itemsets): The memory allocated to
`symbol_count' was used for two different purpose: once to count
the number of occurrences of each symbol, and later reassigned to
`shift_symbol', containing the symbol that can be shifted from a
given state.
Deobfuscate, i.e., allocate, use and free `symbol_count' here
only, and...
(new_itemsets): Allocate `shift_symbol' here.
(allocate_itemsets): symbol_count includes useless nonterminals.
Make room for them.
(free_storage): Use `free', not `XFREE', for pointers that cannot
be null.
(reduce_output): This.
Output to OUT, passed as argument, instead of output_obstack.
(dump_grammar): Likewise.
(reduce_free): New.
Also free V1.
(reduce_grammar): No longer call reduce_output, since...
* src/print.c (print_results): do it.
* src/main.c (main): Call reduce_free;
