String literals as tokens serve two distinct purposes: freeing from
having to implement the keyword matching in the scanner, and improving
error messages. Most of the time both can be achieved at the same
time, but on occasions, it does not work so well.
We promote their use for error messages. We will also still support
the former case, but it is _not_ the recommended approach.
* doc/bison.texi (Tokens from Literals): Clearly state that we don't
recommend looking up the token types in the list of token names.
String literals, which allow for better error messages, are (too)
liberally accepted by Bison, which might result in silent errors. For
instance
%type <exVal> cond "condition"
does not define “condition” as a string alias to 'cond' (nonterminal
symbols do not have string aliases). It is rather equivalent to
%nterm <exVal> cond
%token <exVal> "condition"
i.e., it gives the type 'exVal' to the "condition" token, which was
clearly not the intention.
Introduce -Wdangling-alias to catch this.
* src/complain.h, src/complain.c: Add support for -Wdangling-alias.
(argmatch_warning_args): Sort.
* src/symtab.c (symbol_check_defined): Complain about dangling
aliases.
* doc/bison.texi: Document it.
* tests/input.at (Dangling aliases): New test.
On
%token TOKEN1
%type <ival> TOKEN1 TOKEN2 't'
%token TOKEN2
%%
expr:
bison -Wyacc gives
input.y:2.15-20: warning: POSIX yacc reserves %type to nonterminals [-Wyacc]
2 | %type <ival> TOKEN1 TOKEN2 't'
| ^~~~~~
input.y:2.29-31: warning: POSIX yacc reserves %type to nonterminals [-Wyacc]
2 | %type <ival> TOKEN1 TOKEN2 't'
| ^~~
input.y:2.22-27: warning: POSIX yacc reserves %type to nonterminals [-Wyacc]
2 | %type <ival> TOKEN1 TOKEN2 't'
| ^~~~~~
The messages appear to be out of order, but they are emitted when the
error is found.
* src/symtab.h (symbol_class): Add pct_type_sym, used to denote
symbols appearing in %type.
* src/symtab.c (complain_pct_type_on_token): New.
(symbol_class_set): Check that %type is not applied to tokens.
(symbol_check_defined): pct_type_sym also means undefined.
* src/parse-gram.y (symbol_decl.1): Set the class to pct_type_sym.
* src/reader.c (grammar_current_rule_begin): pct_type_sym also means
undefined.
* tests/input.at (Yacc's %type): New.
As an extension to POSIX Yacc, Bison's %type accepts tokens.
Unfortunately with string literals as implicit tokens, this is
misleading, and led some users to write
%type <exVal> cond "condition"
believing that "condition" would be associated to the 'cond'
nonterminal (see https://github.com/apache/httpd/pull/72).
* doc/bison.texi: Promote %nterm rather than %type to declare the type
of nonterminals.
* README: A few fixes.
Explain how to install color support.
* README-hacking: Rename as...
* README-hacking.md: this, and convert to Markdown.
Improve typography.
Improve explanations about update-test.
* tests/diagnostics.at (Locations from M4, Tabulations and multibyte
characters from M4): These tests are actually checking a message
coming from C, not from M4. Replace with...
(Complaints from M4): This.
We still have a few old C casts in lalr1.cc, let's get rid of them.
Reported by Frank Heckenbach.
Actually, let's monitor all our casts using easy to grep macros.
Let's use these macros to use the C++ standard casts when we are in
C++.
* data/skeletons/c.m4 (b4_cast_define): New.
* data/skeletons/glr.c, data/skeletons/glr.cc,
* data/skeletons/lalr1.cc, data/skeletons/stack.hh,
* data/skeletons/yacc.c:
Use it and/or its casts.
* tests/actions.at, tests/cxx-type.at,
* tests/glr-regression.at, tests/headers.at, tests/torture.at,
* tests/types.at:
Use YY_CAST instead of C casts.
* configure.ac (warn_cxx): Add -Wold-style-cast.
* doc/bison.texi: Disable it.
* data/skeletons/location.cc: Remove the u (for unsigned) suffix from
the initial line and column.
* NEWS: AFAICT, only C++ backends have their location types changed.
We have too many global variables, adding structure would help. For a
start, let's hide some of the variables closer to their usage.
* src/getargs.c, src/files.h (current_file): Move to...
* src/scan-gram.c: here.
* src/scan-gram.h (gram_in, gram__flex_debug): Remove, make them
private to the scanner.
* src/reader.h, src/reader.c (reader): Take a grammar file as argument.
Move the handling of scanner variables to...
* src/scan-gram.l (gram_scanner_open, gram_scanner_close): here.
(gram_scanner_initialize): Remove, replaced by gram_scanner_open.
* src/main.c: Adjust.
* src/parse-gram (%initial-action): here.
(handle_skeleton): Don't depend on the current file name to look for
"local" skeletons (subject to changes coming from "#lines"): depend
only on the initial file name, the one given on the command line.
Currently there are two globals denoting the input file: grammar_file
is the one from the command line, and current_file which might change
because of #line. Use only the former.
* src/complain.c (error_message): here.
* tests/diagnostics.at: Adjust.
This skeleton uses a single stack of state structures, so it is less
likely to benefit from a stack size reduction than yacc.c (which uses
several stacks: state number, value and location). But it will reduce
the size of the LAC stack.
This skeleton was already using int for state numbers, so, contrary to
yacc.c, this brings nothing for large automata.
Overall, it is still nicer to make the skeletons alike.
* data/skeletons/lalr1.cc (state_type): Here.
Reported by Thomas Petazzoni.
https://lists.gnu.org/archive/html/bug-bison/2019-08/msg00000.html
* examples/c/reccalc/local.mk: Complete dependencies, including for
earlier versions of Automake (for sake of our CI, on top of Ubuntu
Xenial/Bionic, which feature only Automake 1.15).
(%D%/scan.c %D%/scan.h): Upgrade to the full version provided in
Automake's documentation.
See https://lists.gnu.org/archive/html/bug-bison/2019-10/msg00061.html
to https://lists.gnu.org/archive/html/bug-bison/2019-10/msg00073.html.
Paul Eggert's changes in gnulib do fix the issue for modern GCCs (7,
8, 9) on macOS. Unfortunately these warnings are back on the
CI (GNU/Linux) with GCC 4.6, 4.7, (not 4.8) and 4.9.
Disable the warning locally.
* configure.ac (warn_common, warn_tests): Remove -Wtype-limits.
* src/system.h (IGNORE_TYPE_LIMITS_BEGIN, IGNORE_TYPE_LIMITS_END): New.
* src/InadequacyList.c, src/parse-gram.c, src/parse-gram.y,
* src/symtab.c: Use it.
This is really weird: GCC points to the LHS of the assignment...
260. headers.at:184: testing Sane headers: api.pure api.push-pull=both ...
tests/headers.at:184: COLUMNS=1000; export COLUMNS; bison --color=no -fno-caret -d -o input.c input.y
tests/headers.at:184: $CC $CFLAGS $CPPFLAGS -c -o input.o input.c
stderr:
input.c: In function 'yyparse':
input.c:1276:16: error: 'yylval' may be used uninitialized in this function [-Werror=maybe-uninitialized]
1276 | yylval = *yypushed_val;
| ~~~~~~~^~~~~~~~~~~~~~~
input.c: In function 'yypull_parse':
input.c:1276:16: error: 'yylval' may be used uninitialized in this function [-Werror=maybe-uninitialized]
1276 | yylval = *yypushed_val;
| ~~~~~~~^~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
stdout:
tests/headers.at:184: exit code was 1, expected 0
See also d87c8ac79a
and 9645a2b20e.
* tests/headers.at (Several parsers, Several parsers): Disable these
warnings when in push parser.
Let's make a difference between places where Perl is required for the
test (AT_PERL_REQUIRE), and the places where it's used to run the
test, but it's not not to run the test (AT_PERL_CHECK).
* tests/local.at (AT_REQUIRE): New.
(AT_PERL_CHECK, AT_PERL_REQUIRE): New.
Use them where appropriate.
* tests/local.mk ($(TESTSUITE)): Beware not to start the line with
'-pi' if Perl is empty, as Make understands this as "it's ok to fail".
Which it is not.
My previous tests (with ./configure PERL=false) have been fooled by
configure, that managed to find perl anyway. This time, I ran this on
a Fedora in Docker, without Perl.
* tests/calc.at, tests/diagnostics.at, tests/headers.at,
* tests/input.at, tests/local.at, tests/named-refs.at,
* tests/output.at, tests/regression.at, tests/skeletons.at,
* tests/synclines.at, tests/torture.at: Don't require Perl.
Currently we face test suite failures in different environments,
because of a conflict between the definitions of isnan by gnulib, and
by the C++ library:
262. headers.at:186: testing Sane headers: %locations %debug c++ ...
./headers.at:186: COLUMNS=1000; export COLUMNS; bison --color=no -fno-caret -d -o input.cc input.y
./headers.at:186: $CXX $CXXFLAGS $CPPFLAGS -c -o input.o input.cc
stderr:
In file included from /usr/include/c++/4.8.2/cmath:44:0,
from /usr/include/c++/4.8.2/random:38,
from /usr/include/c++/4.8.2/bits/stl_algo.h:65,
from /usr/include/c++/4.8.2/algorithm:62,
from location.hh:41,
from input.hh:90,
from input.cc:50:
/u/cs/fac/eggert/src/gnu/bison/lib/math.h: In function 'bool isnan(double)':
/u/cs/fac/eggert/src/gnu/bison/lib/math.h:2849:1: error: new declaration 'bool isnan(double)'
_GL_MATH_CXX_REAL_FLOATING_DECL_2 (isnan, isnan, bool)
^
In file included from /usr/include/features.h:375:0,
from /usr/include/c++/4.8.2/x86_64-redhat-linux/bits/os_defines.h:39,
from /usr/include/c++/4.8.2/x86_64-redhat-linux/bits/c++config.h:2097,
from /usr/include/c++/4.8.2/cstdlib:41,
from input.hh:48,
from input.cc:50:
/usr/include/bits/mathcalls.h:235:1: error: ambiguates old declaration 'int isnan(double)'
__MATHDECL_1 (int,isnan,, (_Mdouble_ __value)) __attribute__ ((__const__));
^
There might be something to do in gnulib about this, but I believe
that gnulib should not be used in the test suite in the first place.
The test suite should work with other compilers than the one used to
compile the package. For a start, Bison sources are more
demanding (C99) than the generated parsers. Last time I tried, tcc
for example, was not able to compile Bison, yet our generated parsers
should compile cleanly with it.
Besides the problem at hand is with the C++ compiler, with is not the
one used to set up gnulib at configuration-time (config.h is mainly
built from probing the C compiler).
We should really not depend on gnulib in tests.
This was introduced in 2001 to check whether including
stdlib.h/string.h is safe thanks to STDC_HEADERS
(2ce1014469). Today, we assume at least
a C90 compiler, it should be safe enough.
* tests/local.at, tests/testsuite.h: Do not include config.h.
* tests/atlocal.in (conftest.cc): Likewise.
(CPPFLAGS): Do not expose lib/, as because of this we might picked up
gnulib replacement headers for system headers.
* tests/input.at: Use int instead of ptrdiff_t, for easier portability
(some machine on the CI did not find ptrdiff_t).
* tests/c++.at: Add missing include for getchar.
A number of portability issues with GCC 4.6 .. 4.9 (inclusive):
input.c:184:7: error: "UCHAR_MAX" is not defined [-Werror=undef]
#elif UCHAR_MAX <= INT_MAX
^
input.c:184:20: error: "INT_MAX" is not defined [-Werror=undef]
#elif UCHAR_MAX <= INT_MAX
^
input.c:202:7: error: "USHRT_MAX" is not defined [-Werror=undef]
#elif USHRT_MAX <= INT_MAX
^
input.c:202:20: error: "INT_MAX" is not defined [-Werror=undef]
#elif USHRT_MAX <= INT_MAX
^
* data/skeletons/c.m4 (b4_c99_int_type_define): Don't assume they are
defined.
Flex should not be required to build Bison or run the test suite (of
course it is needed for maintaining Bison). Yet the Automake
conditional FLEX_WORKS does not work.
* m4/flex.m4 (_AC_PROG_LEX_YYTEXT_DECL): Since this is called
conditionally, don't define LEX_IS_FLEX here, but rather...
(AC_PROG_LEX): here.
* configure.ac: Be more cautious about possibly undefined variables.
Because the checking of the grammar is made by phases after the whole
grammar was read, we sometimes have diagnostics that look weird. In
some case, within one type of checking, the entities are not checked
in the order in which they appear in the file. For instance, checking
symbols is done on the list of symbols sorted by tag:
foo.y:1.20-22: warning: symbol BAR is used, but is not defined as a token and has no rules [-Wother]
1 | %destructor {} QUX BAR
| ^~~
foo.y:1.16-18: warning: symbol QUX is used, but is not defined as a token and has no rules [-Wother]
1 | %destructor {} QUX BAR
| ^~~
Let's sort them by location instead:
foo.y:1.16-18: warning: symbol 'QUX' is used, but is not defined as a token and has no rules [-Wother]
1 | %destructor {} QUX BAR
| ^~~
foo.y:1.20-22: warning: symbol 'BAR' is used, but is not defined as a token and has no rules [-Wother]
1 | %destructor {} QUX BAR
| ^~~
* src/location.h (location_cmp): Be robust to empty file names.
* src/symtab.c (symbol_cmp): Sort by location.
* tests/input.at: Adjust expectations.
From
input.y:1.17-19: warning: symbol baz is used, but is not defined as a token and has no rules [-Wother]
1 | %printer {} foo baz
| ^~~
to
input.y:1.17-19: warning: symbol 'baz' is used, but is not defined as a token and has no rules; did you mean 'bar'? [-Wother]
1 | %printer {} foo baz
| ^~~
| bar
* bootstrap.conf: We need fstrcmp.
* src/symtab.c (symbol_from_uniqstr_fuzzy): New.
(complain_symbol_undeclared): Use it.
* tests/diagnostics.at (Suggestions): New.
* data/bison-default.css (insertion): Rename as...
(fixit-insert): this, as this is what GCC uses.
* src/symtab.c (complain_symbol_undeclared): New.
Use it.
Use quote on the guilty symbol (like GCC does, and we also do
elsewhere).
* tests/input.at: Adjust.
Both are stored in a hash, and back in the days, we used to iterate
over these tables using hash_do_for_each. However, the order of
traversal was not deterministic, which was a nuisance for
deterministic output (and therefore also a problem for tests). So at
some point (83b60c97ee) we generated a
sorted list of these symbols, and symbols_do actually iterated on that
list. But we kept the constraints of using hash_do_for_each, which
requires a lot of ceremonial code, and makes it hard/unnatural to
preserve data between iterations (see the next commit).
Alas, this is C, not C++.
Let's remove this abstraction, and directly iterate on the sorted
tables.
* src/symtab.c (symbols_do): Remove.
Adjust callers to use a simple for-loop instead.
(table_sort): New.
(symbols_check_defined): Use it.
(symbol_check_defined_processor, symbol_pack_processor)
(semantic_type_check_defined_processor, symbol_translation_processor):
Remove.
Simplify the corresponding functions (that no longer need to return a
bool).
This commit adds the suggestion in green, on the line below the
caret-and-tildes.
foo.y:1.1-14: warning: deprecated directive: '%error-verbose', use '%define parse.error verbose' [-Wdeprecated]
1 | %error-verbose
| ^~~~~~~~~~~~~~
| %define parse.error verbose
The current approach, with location_caret_suggestion, is fragile:
there's a protocol of calls to the complain functions which is strict.
We should rather have a richer structure describing the diagnostics,
including with submessages such as the suggestions, passed in the end
to the routines in charge of formatting and printing them.
* src/location.h, src/location.c (location_caret_suggestion): New.
* src/complain.c (deprecated_directive): Use it.
* tests/diagnostics.at, tests/input.at: Adjust expectations.
* src/location.c (caret_set_file): New.
Store the current line's length in caret_info.line_len.
Pay attention to fseek's return value.
Extracted from...
(location_caret): here.
I no longer agree with that item, there are indeed two things to
report: lack of definition, and being useless. We could have either
one without the other, they are not directly related.
input.c: In function 'int yyparse()':
input.c: error: conversion to 'long int' from 'long unsigned int'
may change the sign of the result [-Werror=sign-conversion]
yyes_capacity = sizeof yyesa / sizeof *yyes;
^
cc1plus: all warnings being treated as errors
* data/skeletons/yacc.c: here.
GCC 4.8 reports:
input.y:57:33: error: conversion to 'int' from 'long unsigned int'
may alter its value [-Werror=conversion]
int input_elts = sizeof input / sizeof input[0];
^
* tests/local.at (AT_YYLEX_DEFINE(c)): Add a cast (sorry, Paul!).
For instance with GCC 4.9 and --enable-gcc-warnings:
25. input.at:1201: testing Torturing the Scanner ...
../../tests/input.at:1344: $CC $CFLAGS $CPPFLAGS -c -o input.o input.c
stderr:
input.c:239:18: error: "__STDC_VERSION__" is not defined [-Werror=undef]
# elif 199901 <= __STDC_VERSION__
^
input.c:256:18: error: "__STDC_VERSION__" is not defined [-Werror=undef]
# elif 199901 <= __STDC_VERSION__
^
* data/skeletons/yacc.c: Check that __STDC_VERSION__ is defined before
using it.
Akim Demaille