The C, C++ and D skeletons used to show the stack right after popping
the stack during the reduction. Now that the stack is printed after
reaching a new state, that has become useless:
Entering state 1
Stack now 0 1
Reducing stack by rule 5 (line 83):
$1 = token "number" (1)
-> $$ = nterm exp (1)
Stack now 0
Entering state 8
Stack now 0 8
Remove the "Stack now 0" line.
* data/skeletons/lalr1.cc, data/skeletons/lalr1.d,
* data/skeletons/lalr1.java, data/skeletons/yacc.c:
Here.
Currently, if we have long rules and series of shift, we stack states
without showing stack. Let's be more incremental, and do how the Java
skeleton does.
* data/skeletons/lalr1.cc, data/skeletons/lalr1.d,
* data/skeletons/yacc.c:
Here.
Adjust test cases.
* tests/torture.at (AT_DATA_STACK_TORTURE): Disable stack traces: this
test produces a very large stack, and showing the stack each time we
shift a token goes quadatric.
The Java skeleton displays
Reading a token:
Next token is token "number" (1)
while the other display
Reading a token: Next token is token "number" (1)
When generating logs in the scanner, the first part is separated from
the second, and the end of the scanner logs have the second part
pasted in. So let's propagate the Java way, but with the colon.
* data/skeletons/glr.c, data/skeletons/lalr1.cc, data/skeletons/lalr1.d,
* data/skeletons/lalr1.java, data/skeletons/yacc.c: Do it.
Adjust test cases and doc.
* tests/local.at (AT_LANG_MATCH): New.
(AT_YYERROR_DECLARE(java), AT_YYERROR_DECLARE_EXTERN(java)): New.
* tests/calc.at: The grammar file for Java is quite different for the
others, and continuing to assemble it from pieces makes the grammar
file hard to understand. Let's also dispatch on the language to
assemble it, and isolate Java from the others.
Most of this comes from java.at.
AFAICT, autoboxing/unboxing was added in Java 5 (September 30, 2004).
I think we can afford to use it. It should help us merge some Java
tests with the main ones.
However, beware that != does not unbox: it compares the object
addresses.
* examples/java/Calc.y, tests/java.at: Simplify.
* examples/java/Calc.test, tests/java.at: Improve tests.
When building the test cases, emitting code in the epilogue is very
constraining. Let's make it simpler thanks to %code epilogue.
However, I don't want to document this: it is bad style to use it (we
should avoid having too many ways to write the same thing,
TI!MTOWTDI), just put your code in the true epilogue section.
* data/skeletons/glr.c, data/skeletons/lalr1.d, data/skeletons/lalr1.java,
* data/skeletons/yacc.c: Implement support for %code epilogue.
Remove useless comments.
* tests/calc.at, tests/java.at: Simplify.
We used to display the unexpected token first:
$ bison foo.y
foo.y:1.8-13: error: syntax error, unexpected %token, expecting character literal or identifier or <tag>
1 | %token %token
| ^~~~~~
GCC uses a different format:
$ gcc-mp-9 foo.c
foo.c:1:5: error: expected identifier or '(' before ')' token
1 | int()()()
| ^
and so does Clang:
$ clang-mp-9.0 foo.c
foo.c:1:5: error: expected identifier or '('
int()()()
^
1 error generated.
They display the unexpected token last (or not at all). Also, they
don't waste width with "syntax error". Let's try that. It gives, for
the same example as above:
$ bison foo.y
foo.y:1.8-13: error: expected character literal or identifier or <tag> before %token
1 | %token %token
| ^~~~~~
* src/complain.h, src/complain.c (syntax_error): New.
* src/parse-gram.y (yyreport_syntax_error): Use it.
As a test case, support translations in Bison itself.
* src/parse-gram.y: Mark the translatable tokens.
While at it, use clearer names.
* tests/input.at: Adjust expectations.
Just as the yacc.c skeleton, the lalr1.cc skeleton should reject
invalid values for parse.lac.
* data/skeletons/lalr1.cc: check validity of parse.lac
* tests/input.at: new test cases
Just as the yacc.c skeleton, the lalr1.cc skeleton should reject
invalid values for parse.lac.
* data/skeletons/lalr1.cc: check validity of parse.lac
* tests/input.at: new test cases
Some users would like to avoid having to "parse" the *.y file to find
the strings to translate. Let's issue the translatable tokens with N_
to allow "parsing" the generated parsers instead.
See
https://lists.gnu.org/archive/html/bison-patches/2019-01/msg00015.html
* src/output.c (prepare_symbol_names): Issue symbol_names with N_()
markup.
* src/output.c (escape_trigraphs, xescape_trigraphs): New.
(prepare_symbol_names): Use it.
* tests/regression.at: Check the handling of trigraphs with
parse.error = detailed.
"detailed" error messages are almost like "verbose", except that we
don't double escape them, they don't get inner quotes, we don't use
yytnamerr, and we hide the table.
"custom" is exposed with the "detailed" tokens, not the "verbose"
ones: they are not double-quoted.
Because there's a risk that some people use yytname even without
"verbose", let's keep yytname (instead of yys_name) in "simple"
parse.error.
* src/output.c (prepare_symbol_names): Be ready to output symbol names
unquoted.
(prepare_symbol_names): Output both the old tname table, and the new
symbol_names one.
* data/skeletons/bison.m4: Accept 'detailed'.
* data/skeletons/yacc.c: When parse.error is 'detailed', don't emit
yytname and yytnamerr, just yysymbol_name with the table inside.
* tests/calc.at: Adjust.
Be robust to newer versions of Autoconf where the package URL defaults
to https instead of http.
* configure.ac (AC_INIT): Use https.
* tests/report.at: Adjust expected output s/http/https/
to match updated URL.
Currently we get warnings with GCC 4.8 when running the
maintainer-check-g++ tests:
143. skeletons.at:85: testing Installed skeleton file names ...
../../tests/skeletons.at:120: COLUMNS=1000; export COLUMNS; bison --color=no -fno-caret --skeleton=yacc.c -o input-cmd-line.c input-cmd-line.y
../../tests/skeletons.at:121: $CC $CFLAGS $CPPFLAGS $LDFLAGS -o input-cmd-line input-cmd-line.c $LIBS
stderr:
input-cmd-line.c: In function 'int yysyntax_error(long int*, char**, const yyparse_context_t*)':
input-cmd-line.c:977:52: error: conversion to 'int' from 'long int' may alter its value [-Werror=conversion]
YYSIZEOF (yyarg) / YYSIZEOF (*yyarg));
^
cc1plus: all warnings being treated as errors
stdout:
../../tests/skeletons.at:121: exit code was 1, expected 0
and
429. calc.at:823: testing Calculator parse.error=custom %locations api.prefix={calc} ...
../../tests/calc.at:823: COLUMNS=1000; export COLUMNS; bison --color=no -fno-caret -Wno-deprecated -o calc.c calc.y
../../tests/calc.at:823: $CC $CFLAGS $CPPFLAGS $LDFLAGS -o calc calc.c $LIBS
stderr:
calc.y: In function 'int yyreport_syntax_error(const yyparse_context_t*)':
calc.y:157:58: error: conversion to 'int' from 'long unsigned int' may alter its value [-Werror=conversion]
int n = yysyntax_error_arguments (ctx, arg, sizeof arg / sizeof *arg);
^
cc1plus: all warnings being treated as errors
stdout:
../../tests/calc.at:823: exit code was 1, expected 0
We could use a cast to avoid the warning, but it becomes too
cluttered. We can also use YYPTRDIFF_T, but that forces the user to
use YYPTRDIFF_T too, although this is an array of tokens, which is
limited by YYNTOKENS, an int. So let's completely avoid this warning.
* data/skeletons/yacc.c, tests/local.at (yyreport_syntax_error): Avoid
relying on sizeof to compute the array capacity.
Enhance the calculator tests: show that passing arguments to yyerror
works.
* tests/calc.at: Add a new parse-param, nerrs, which counts the number
of syntax errors in a run.
* tests/local.at: Adjust to handle the new 'nerrs' argument, when
present.
The custom error reporting function show sees the user's additional
arguments. Let's experiment with passing them as arguments to
yyreport_syntax_error, but maybe storing them in the context would be
a bettter alternative.
* data/skeletons/yacc.c (yyreport_syntax_error): Handle the
parse-params.
* tests/calc.at, tests/local.at: Adjust.
Currently the parse-params are tested in calc.at by checking that the
global variable and the parse-params have the same value. But it does
not check that value, that could remain being 0 just as well.
* tests/calc.at: Don't define the params when they are not used.
Check the final value of result and count.
Also, do count the number of line of logs.
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 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.
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.
* data/skeletons/glr.c (YYASSERT): Rename as...
(YY_ASSERT): this, for consistency with yacc.c, and also to emphasize
the fact that this is not for the end user (YY_ prefix).
* tests/glr-regression.at: Define parse.assert.
The current code for yysyntax_error for %define parse.error verbose is
fishy (given that YYEMPTY is -2, invalid argument for yytname[]):
static int
yysyntax_error ([...])
{
YYPTRDIFF_T yysize0 = yytnamerr (YY_NULLPTR, yytname[yytoken]);
[...]
if (yytoken != YYEMPTY)
A nearby comment reports
The only way there can be no lookahead present (in yychar) is if
this state is a consistent state with a default action. Thus,
detecting the absence of a lookahead is sufficient to determine
that there is no unexpected or expected token to report. In that
case, just report a simple "syntax error".
So it _is_ possible to call yysyntax_error with yytoken == YYEMPTY,
albeit quite difficult when meaning to, so virtually impossible by
accident (after all, there was never a bug report about this).
I failed to produce a test case, but Joel E. Denny provided me with
one (added to the test suite below). The yacc.c skeleton fails on
this, and once fixed dies on a second problem. The glr.c skeleton was
also dying, but immediately of this second problem.
Indeed we were not allocating space for the error message's final \0.
This was hidden by the fact that we only had error messages with at
least an unexpected token displayed, so with at least one "%s" in the
format string, whose size (2) was included (incorrectly) in the final
size of the message (where the %s have been replaced by the actual
content).
* data/skeletons/glr.c, data/skeletons/yacc.c (yysyntax_error):
Do not invoke yytnamerr on YYEMPTY.
Clarify the computation of the length of the _final_ error message,
with the NUL terminator but without the '%s's.
* tests/conflicts.at (Syntax error in consistent error state):
New, contributed by Joel E. Denny.
Having a file named "exception" is risky: the compiler might use that
file in #include.
Reported by 马俊 <majun123@whu.edu.cn>.
* tests/local.at (AT_SKIP_IF_EXCEPTION_SUPPORT_IS_POOR): Generate
'exceptions', not 'exception'.
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.
