Until we have a decent reimplementation of glr.cc, we have to use
tricks to shoehorn C++ symbols to the C engine of glr.c. Some of them
are done via #define. Unfortunately in Bison 3.6 some of these we
done in the header file, which broke valid user code.
Reported by Egor Pugin.
https://lists.gnu.org/r/bug-bison/2020-06/msg00003.html
* data/skeletons/glr.cc: Stop playing tricks with b4_pre_epilogue.
(b4_glr_cc_setup, b4_glr_cc_cleanup): New.
Much cleaner way to instal glr.cc's scaffolding around glr.c.
* data/skeletons/glr.c: Adjust to use them.
* data/skeletons/lalr1.java (Location): Make it a static class.
(Lexer.yylex, Lexer.getLVal, Lexer.getStartPos, Lexer.getEndPos):
These are not needed in push parsers.
* examples/java/calc/Calc.y: Demonstrate push parsers in the Java.
* doc/bison.texi: Push parsers have been supported for a long time,
remove incorrect statements stating the opposite.
Some people have been using that symbol. Some even have #defined it
themselves.
https://lists.gnu.org/r/bison-patches/2020-04/msg00138.html
Let's provide backward compatibility, having it point to YYUNDEF, so
that an error message is generated.
* data/skeletons/yacc.c (YYERRCODE): New, at the exact same location
it was defined before.
These are internal details. `type_get ()` is still there to ensure
backward compatibility, `kind ()` being the modern way.
* data/skeletons/c++.m4 (by_type, by_type::type): Rename as...
(by_kind, by_kind::kind_): this.
Adjust dependencies.
From
public interface Lexer {
/* Token kinds. */
/** Token number, to be returned by the scanner. */
static final int YYEOF = 0;
/** Token number, to be returned by the scanner. */
static final int YYERRCODE = 256;
/** Token number, to be returned by the scanner. */
static final int YYUNDEF = 257;
/** Token number, to be returned by the scanner. */
static final int BANG = 258;
...
/** Deprecated, use b4_symbol(0, id) instead. */
public static final int EOF = YYEOF;
to
public interface Lexer {
/* Token kinds. */
/** Token "end of file", to be returned by the scanner. */
static final int YYEOF = 0;
/** Token error, to be returned by the scanner. */
static final int YYerror = 256;
/** Token "invalid token", to be returned by the scanner. */
static final int YYUNDEF = 257;
/** Token "!", to be returned by the scanner. */
static final int BANG = 258;
...
/** Deprecated, use YYEOF instead. */
public static final int EOF = YYEOF;
* data/skeletons/java.m4 (b4_token_enum): Display the symbol's tag in
comment.
* data/skeletons/lalr1.java: Address overquotation issue.
* examples/java/calc/Calc.y, examples/java/simple/Calc.y: Use YYEOF,
not EOF.
* src/output.c (prepare_symbol_names): Don't play tricks with the
symbols, it's quite too late.
(has_translations): Move to...
* src/symtab.c: here.
(symbols_pack): Use it to enable translation for special symbols.
symbol_type::token () was removed: it returned the token kind of a
symbol. To do that, one needs to convert from the symbol kind to the
token kind, which requires a table.
This broke some users' unit tests for scanners, see
https://lists.gnu.org/r/bug-bison/2020-01/msg00001.htmlhttps://lists.gnu.org/r/bug-bison/2020-03/msg00020.htmlhttps://lists.gnu.org/r/help-bison/2020-04/msg00005.html
Instead of making this possible again, let's check the symbol's kind
instead. So give proper access to a symbol's kind.
That feature existed, undocumented, as 'type_get()'. Let's rename
this as 'kind()'.
* data/skeletons/c++.m4, data/skeletons/glr.cc,
* data/skeletons/lalr1.cc (type_get): Rename as...
(kind): This.
(type_get): Install a backward compatibility alias.
* doc/bison.texi (Complete Symbols): Document symbol_type and
symbol_type::kind.
* data/skeletons/c++.m4: Define the old names in terms on the new
ones, instead of the converse.
* doc/bison.texi (C++ Parser Interface): Be more extensive about
token_kind_type.
Why didn't I think about this before??? symbolName should be a method
of SymbolKind.
* data/skeletons/lalr1.java (YYParser::yysymbolName): Move as...
* data/skeletons/java.m4 (SymbolKind::getName): this.
Make the table a static final table, not a local variable.
Adjust dependencies.
* doc/bison.texi (Java Parser Interface): Document i18n.
(Java Parser Context Interface): Document SymbolKind.
* examples/java/calc/Calc.y, tests/local.at: Adjust.
The name "$end" is nice in the report, in particular it avoids that
pointed-rules (aka items) be too long. It also helps keeping them
"standard".
But it is bad in error messages, we should report "end of file" (or
maybe "end of input", this is debatable). So, unless the user already
defined the alias for the error token herself, make it "end of file".
It should even be translated if the user already translated some
tokens, so that there is now no strong reason to redefine the $end
token.
* src/output.c (prepare_symbol_names): Issue "end of file" instead of
"$end".
* data/skeletons/lalr1.java (yytnamerr_): Remove the renaming hack.
* build-aux/update-test: Accept files with names containing a "+",
such as c++.at.
* tests/actions.at, tests/c++.at, tests/conflicts.at,
* tests/glr-regression.at, tests/regression.at, tests/skeletons.at:
Adjust.
Yet, don't change the structure identifier to avoid introducing
conflicts in Vincent Imbimbo's PR (which, amusingly enough, is about
conflicts).
* src/symtab.c: here.
* tests/diagnostics.at, tests/input.at: Adjust.
yy::parser features a parse() function, not a yyparse() one.
* data/skeletons/lalr1.cc (yyreport_syntax_error)
(context::yyexpected_tokens): Rename as...
(report_syntax_error, context::expected_tokens): these.
Currently EOF is handled in an adhoc way, with a #define YYEOF 0 in
the implementation file. As a result, the user has to define her own
EOF token if she wants to use it, which is a pity.
Give the $end token a visible kind name, YYEOF. Except that in C,
where enums are not scoped, we would have collisions between all the
definitions of YYEOFs in the header files, so in C, make it
<api.PREFIX>EOF.
* data/skeletons/c.m4 (YYEOF): Override its name to avoid collisions.
Unless the user already gave it a different name.
* data/skeletons/glr.c (YYEOF): Remove.
Use ]b4_symbol(0, [id])[ instead.
Add support for "pre_epilogue", for glr.cc.
* data/skeletons/glr.cc: Remove dead code (never emitted #undefs).
* data/skeletons/yacc.c
* src/parse-gram.c
* src/reader.c
* src/symtab.c
* tests/actions.at
* tests/input.at
There are people out there that do use YYERRCODE (the token kind of
the error token). See for instance
3812012bb7/unixODBC-2.3.2/Drivers/nn/yylex.c.
Currently, YYERRCODE is defined by yacc.c in an adhoc way as a #define
in the *.c file only. It belongs with the other token kinds.
YYERRCODE is not a nice name, it does not fit in our naming scheme.
YYERROR would be more logical, but it collides with the YYERROR macro.
Shall we keep the same name in all the skeletons? Besides, to avoid
collisions in C, we need to apply the api prefix: YYERRCODE is
actually <PREFIX>ERRCODE. This is not needed in the other languages.
* data/skeletons/bison.m4 (b4_symbol_token_kind): New.
Map the error token to "YYERRCODE".
* data/skeletons/yacc.c (YYERRCODE): Don't define it, it's handled by...
* src/output.c (prepare_symbol_definitions): this.
* tests/input.at (Redefining the error token): Check it.
That's one nice benefit from using enums.
* data/skeletons/lalr1.java (YYSYMBOL_YYEMPTY): No longer define it.
Use 'null' instead.
* examples/java/calc/Calc.y, tests/local.at: Adjust.
* data/skeletons/bison.m4, data/skeletons/c++.m4, data/skeletons/c.m4,
* data/skeletons/glr.cc, data/skeletons/lalr1.cc,
* data/skeletons/lalr1.d, data/skeletons/lalr1.java:
Refer to the "kind" of a symbol, not its "type", where appropriate.
The Java enums are very different from the C model. As a consequence,
one cannot "build" an enum directly from an integer, we must retrieve
it. That's the purpose of the SymbolType.get class method.
* data/skeletons/java.m4 (b4_symbol_enum, b4_case_code_symbol)
(b4_declare_symbol_enum): New.
* data/skeletons/lalr1.java: Use SymbolType,
SymbolType.YYSYMBOL_YYEMPTY, etc.
* examples/java/calc/Calc.y, tests/local.at: Adjust.
This is not only cleaner, it also protects us from mixing signed
values (YYEMPTY is #defined as -2) with unsigned types (the
yysymbol_type_t enum is typically compiled as a small unsigned).
For instance GCC 9:
input.c: In function 'yyparse':
input.c:1107:7: error: conversion to 'unsigned int' from 'int'
may change the sign of the result
[-Werror=sign-conversion]
1107 | yyn += yytoken;
| ^~
input.c:1107:10: error: conversion to 'int' from 'unsigned int'
may change the sign of the result
[-Werror=sign-conversion]
1107 | yyn += yytoken;
| ^~~~~~~
input.c:1108:47: error: comparison of integer expressions of
different signedness:
'yytype_int8' {aka 'const signed char'} and
'yysymbol_type_t' {aka 'enum yysymbol_type_t'}
[-Werror=sign-compare]
1108 | if (yyn < 0 || YYLAST < yyn || yycheck[yyn] != yytoken)
| ^~
input.c:702:25: error: operand of ?: changes signedness from 'int'
to 'unsigned int' due to unsignedness of
other operand [-Werror=sign-compare]
702 | #define YYEMPTY (-2)
| ^~~~
input.c:1220:33: note: in expansion of macro 'YYEMPTY'
1220 | yytoken = yychar == YYEMPTY ? YYEMPTY : YYTRANSLATE (yychar);
| ^~~~~~~
input.c:1220:41: error: unsigned conversion from 'int' to
'unsigned int' changes value
from '-2' to '4294967294'
[-Werror=sign-conversion]
1220 | yytoken = yychar == YYEMPTY ? YYEMPTY : YYTRANSLATE (yychar);
| ^
Eventually, it might be interesting to move away from -2 (which is the
only possible negative symbol number) and use the next available
number, to save bits. We could actually even simply use "0" and shift
the rest, which would allow to write "!yytoken" to mean really
"yytoken != YYEMPTY".
* data/skeletons/c.m4 (b4_declare_symbol_enum): Define YYSYMBOL_YYEMPTY.
* data/skeletons/yacc.c: Use it.
* src/parse-gram.y (yyreport_syntax_error): Use YYSYMBOL_YYEMPTY, not
YYEMPTY, when dealing with a symbol.
* tests/regression.at: Adjust.
There's a number of advantage in exposing the symbol (internal)
numbers:
- custom error messages can use them to decide how to represent a
given symbol, or a set of symbols.
- we need something similar in uses of yyexpected_tokens. For
instance, currently, bistromathic's completion() reads:
int ntokens = expected_tokens (line, tokens, YYNTOKENS);
[...]
for (int i = 0; i < ntokens; ++i)
if (tokens[i] == YYTRANSLATE (TOK_VAR))
[...]
else if (tokens[i] == YYTRANSLATE (TOK_FUN))
[...]
else
[...]
- now that it's a compile-time expression, we can easily build static
tables, switch, etc.
- some users depended on the ability to get the token number from a
symbol to write test cases for their scanners. But Bison 3.5
removed the table this feature depended upon (a reverse
yytranslate). Now they can check against the actual symbol number,
without having pay (space and time) a conversion.
See https://lists.gnu.org/r/bug-bison/2020-01/msg00001.html, and
https://lists.gnu.org/archive/html/bug-bison/2020-03/msg00015.html.
- it helps us clearly separate the internal symbol numbers from the
external token numbers, whose difference is sometimes blurred in the
code when values coincide (e.g. "yychar = yytoken = YYEOF").
- it allows us to get rid of ugly macros with inconsistent names such
as YYUNDEFTOK and YYTERROR, and to group related definitions
together.
- similarly it provides a clean access to the $accept symbol (which
proves convenient in a current experimentation of mine with several
%start symbols).
Let's declare this type as a private type (in the *.c file, not
the *.h one). So it does not need to be influenced by the api prefix.
* data/skeletons/bison.m4 (b4_symbol_sid): New.
(b4_symbol): Use it.
* data/skeletons/c.m4 (b4_symbol_enum, b4_declare_symbol_enum): New.
* data/skeletons/yacc.c: Use b4_declare_symbol_enum.
(YYUNDEFTOK, YYTERROR): Remove.
Use the corresponding symbol enum instead.
* upstream/maint:
maint: post-release administrivia
version 3.5.3
news: update for 3.5.3
yacc.c: make sure we properly propagated the user's number for error
diagnostics: don't crash because of repeated definitions of error
style: initialize some struct members
diagnostics: beware of zero-width characters
diagnostics: be sure to close the styling when lines are too short
muscles: fix incorrect decoding of $
code: be robust to reference with invalid tags
build: fix typo
doc: update recommandation for libtextstyle
style: comment changes
examples: use consistently the GFDL header for readmes
style: remove useless declarations
typo: succesful -> successful
README: point to tests/bison, and document --trace
gnulib: update
maint: post-release administrivia
Currently pstate_new does not set up its variables, this task is left
to yypush_parse. This was probably to share more code with usual pull
parsers, where these (local) variables are indeed initialized by
yyparse.
But as a consequence yyexpected_tokens crashes at the very beginning
of the parse, since, for instance, the stacks are not even set up.
See https://lists.gnu.org/r/bison-patches/2020-03/msg00001.html.
The fix could have very simple, but the documentation actually makes
it very clear that we can reuse a pstate for several parses:
After yypush_parse returns a status other than YYPUSH_MORE, the
parser instance yyps may be reused for a new parse.
so we need to restore the parser to its pristine state so that (i) it
is ready to run the next parse, (ii) it properly supports
yyexpected_tokens for the next run.
* data/skeletons/yacc.c (b4_initialize_parser_state_variables): New,
extracted from the top of yyparse/yypush_parse.
(yypstate_clear): New.
(yypstate_new): Use it when push parsers are enabled.
Define after the yyps macros so that we can use the same code as the
regular pull parsers.
(yyparse): Use it when push parsers are _not_ enabled.
* examples/c/bistromathic/bistromathic.test: Check the completion on
the beginning of the line.
These macros have been extremely useful when we had to support K&R C,
which we dropped long ago. Now, they merely make the code uselessly
hard to read.
* data/skeletons/c.m4, data/skeletons/glr.c, data/skeletons/glr.cc,
* data/skeletons/yacc.c:
Stop using b4_function_define.
Since Bison 2.7, output was indented four spaces for explanatory
statements. For example:
input.y:2.7-13: error: %type redeclaration for exp
input.y:1.7-11: previous declaration
Since the introduction of caret-diagnostics, it became less clear.
Remove the indentation and display submessages as in GCC:
input.y:2.7-13: error: %type redeclaration for exp
2 | %type <float> exp
| ^~~~~~~
input.y:1.7-11: note: previous declaration
1 | %type <int> exp
| ^~~~~
* src/complain.h (SUB_INDENT): Remove.
(warnings): Add "note" to the enum.
* src/complain.h, src/complain.c (complain_indent): Replace by...
(subcomplain): this.
Adjust all dependencies.
* tests/actions.at, tests/diagnostics.at, tests/glr-regression.at,
* tests/input.at, tests/named-refs.at, tests/regression.at:
Adjust expectations.
