Provide users with a means to query for the currently allowed tokens.
Could be used for autocompletion for instance.
* data/skeletons/yacc.c (yyexpected_tokens): New, extracted from
yysyntax_error_arguments.
* examples/c/calc/calc.y (PRINT_EXPECTED_TOKENS): New.
Use it.
We use a different format to check parse.error custom. Compute the
"verbose" one from it instead of forcing the test author to provide
the various formats of expected error messages.
* tests/calc.at (_AT_CHECK_CALC_ERROR): Handle this transformation
when needed.
Simplify callers.
* tests/local.at (AT_ERROR_CUSTOM_IF, AT_ERROR_VERBOSE_IF)
(AT_ERROR_SIMPLE_IF): New.
(AT_YYERROR_DEFINE(c)): Generate yyreport_syntax_error.
* tests/calc.at (_AT_CHECK_CALC_ERROR): Accept custom error messages
as additional test case.
Use it.
Add a new test case for %define parse.error custom.
When parse.error is custom, let users define a yyreport_syntax_error
function, and use it.
* data/skeletons/bison.m4 (b4_error_verbose_if): Accept 'custom'.
* data/skeletons/yacc.c: Implement it.
* examples/c/calc/calc.y: Experiment with it.
That allows users to cover more cases, such as easily filtering some
arguments they don't want to expose. But they now have to call
yysymbol_name explicitly.
* data/skeletons/yacc.c (yysyntax_error_arguments, yysyntax_error):
Deal with symbol numbers instead of symbol names.
Isolate a function that returns the list of expected and unexpected
tokens. It will be exposed to users willing to customize their error
messages.
* data/skeletons/yacc.c (yyparse_context_t): New.
(yyerror_message_arguments): New, extracted from yysyntax_error.
When not empty, AT_PARSE_PARAMS was guaranteed to end with a comma.
Remove the trailing comma, so that we can use AT_PARSE_PARAMS at the
end of the arguments, not only at the beginning.
* tests/local.at: here.
Unfortunately, m4_append relies on the macro not being defined whereas
we would have preferred it to check for emptiness. So use
m4_define/m4_undefine instead of m4_pushdef/m4_popdef.
Let's have C be the reference, and match it elsewhere. Maybe C is too
verbose and some adjustments are needed, but then that would be done
in another batch of patches.
* data/skeletons/lalr1.cc: Print the stack once we popped after
YYERROR, and before emptying the stack at the end of parsing.
Currently the C and C++ parse traces differ in the order in which the
stack is displayed: bottom up in C, top down in C++. Let's stick to
the C order.
* data/skeletons/stack.hh (stack::iterator, stack::const_iterator)
(begin, end): Be forward, not backward.
Provide the users with a public API to get the name of the tokens. A
thin wrapper around yytname.
* data/skeletons/yacc.c (yysymbol_name): New.
Use it.
I was hoping it would help us catch warnings when char is
unsigned (see 78bb152a63), but it does
not seem to help. It's a pity that the compiler is the same all over
the place, I would have preferred testing others.
* .travis.yml: here.
Supporting YYERROR_VERBOSE via cpp is a nuisance: m4 is in charge of
handling alternatives. When adding more options for %define
parse.error, supporting both CPP and M4 is too complex. Anyway,
YYERROR_VERBOSE was deprecated long ago.
* data/skeletons/yacc.c: Use m4 only to handle verbose/simple error
messages.
I would like to offer new ways to build the error message. As a first
step, let's simplify yysyntax_error whose first loop does two things
at the same time: (i) collect the tokens to be reported in the error
message, and (ii) accumulate their sizes and possibly return
"overflow". Let's pull (ii) in a second step.
Then test 525 (regression.at:1193: parse.error=verbose overflow)
failed. This test checks that we correctly report "memory overflow"
when the error message is too large. However the test is mistaken: it
is triggered in a place where there are five (large) expected tokens,
so anyway we would not display them, so there is no (memory) overflow
here! Transform this test to (i) check that indeed there is no
overflow, and (ii) create syntax_error3 which does check the intended
behavior, but with four expected tokens.
* data/skeletons/yacc.c (yysyntax_error): First compute the list of
arguments, then compute yysize.
* tests/regression.at (parse.error=verbose overflow): Enhance and fix.
GCC's -Wchar-subscripts may report issues on platforms where char is
unsigned. Unfortunately the current CI does not reproduce the
problem. But that would allow contributors to report issues if the
warning appears somewhere.
See 139d065594.
Problem reported by Andy Fiddaman in:
https://lists.gnu.org/r/bug-bison/2019-12/msg00021.html
* configure.ac (warn_common): Add -Wchar-subscripts.
Problem reported by Andy Fiddaman in:
https://lists.gnu.org/r/bug-bison/2019-12/msg00021.html
* data/skeletons/yacc.c (yy_reduce_print, yy_lac, yysyntax_error)
(yyreturn): If I might be a char, write a[+I] instead of a[I],
so that ‘gcc -Wchar-subscripts’ does not complain.
Another breakage revealed by vcsn.
* data/skeletons/c++.m4 (yytranslate_): Do not hard code "yy" and
"parser", both can be changed by the user.
Actually, since we are in the parser itself, there's really no need to
qualify the type.
