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EOF rules with multiple blocks #280

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brk opened this issue Apr 17, 2020 · 9 comments
Closed

EOF rules with multiple blocks #280

brk opened this issue Apr 17, 2020 · 9 comments

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@brk
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brk commented Apr 17, 2020

When using multiple blocks within a single function, the EOF rules in each block will (re-)define the same yyeof symbol. (This behavior applies to both 1.3 and HEAD). The resulting code cannot be compiled.

I took a quick look at the code in emit_action.cc but didn't see an obvious way of obtaining a block identifier. Hopefully this isn't a difficult patch to produce for someone more familiar with the codebase!

@trofi
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trofi commented Apr 18, 2020

Can you provide simple example of source .re code that exhibits bad code generation?

@skvadrik
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skvadrik commented Apr 18, 2020

I've come up with this example (for simplicity it doesn't do buffer refilling and YYFILL always fails, but that's irrelevant to the problem):

#include <assert.h>
#include <string.h>

static int lex(const char *str, unsigned int &count)
{
    const char *YYCURSOR = str;
    const char *YYLIMIT  = YYCURSOR + strlen(str);
    count = 0;
    /*!re2c
        re2c:define:YYCTYPE = char;
        re2c:define:YYFILL = "false"; // always failed
        re2c:define:YYFILL:naked = 1;
        re2c:eof = 0;

        wsp   = [ \n]+;
        char1 = [a-zA-Z_];
        char  = char1 | [0-9];
        word  = char1 char+;
    */
loop:
    /*!re2c
        *          { return 1; }
        $          { return 0; }
        "" / char1 { goto word; }
        wsp        { goto loop; }
    */
word:
    /*!re2c
        *    { return 2; }
        $    { return 0; }
        word { ++count; goto loop; }
    */
}

int main()
{
    unsigned int count;
    assert(lex("aa bb cc", count) == 0 && count == 3);
    assert(lex("aa 1b cc", count) == 1);
    assert(lex("aa b cc", count) == 2);
    return 0;
}

To be run as:

re2c -W example.re -oexample.cpp && g++ -Wall example.cpp -oexample && ./example

skvadrik added a commit that referenced this issue Apr 18, 2020
This allows to use EOF rule with multiple blocks in the same function
(previously re2c generated duplicate EOF labels, so the code did not
compile).

This fixes bug #280: "EOF rules with multiple blocks", reported by brk.
@skvadrik
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skvadrik commented Apr 18, 2020

Fix: 1503a74.

@brk

I took a quick look at the code in emit_action.cc but didn't see an obvious way of obtaining a block identifier.

Re2c doesn't yet have a concept of named blocks, so I added "block ID" to the label. The number does not represent re2c block, just some inner program block, so it is quite meaningless. But EOF labels are not part of the stable API exposed to the users, so re2c will generate more beautiful labels in future.

Also, as @trofi pointed out, it is good to provide an example (this time it was easy for me to construct one, but user examples are more versatile and make better tests).

@brk
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brk commented Apr 18, 2020

I apologize for not providing a reduced testcase from the start.

Thank you very much for the rapid fix!

@jinscoe123
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jinscoe123 commented Jun 27, 2020

Hey, I am still experiencing this issue (using re2c compiled at HEAD), but with a slightly more complicated example, involving the use of conditions and the EOF rule:

#include <assert.h>
#include <string.h>


/*!types:re2c */

int lex(const char* cur)
{
    const char* lim;
    const char* mrk;

    char yych;

    int condition = yycinit;

    lim = cur + strlen(cur);
loop:
    mrk = cur;

    /*!re2c
        re2c:define:YYCTYPE = char;
        re2c:define:YYLIMIT  = lim;
        re2c:define:YYCURSOR = cur;
        re2c:define:YYMARKER = mrk;
        re2c:variable:yych  = yych;
        re2c:yych:emit = 0;
        re2c:define:YYGETCONDITION = 'condition';
        re2c:define:YYGETCONDITION:naked = 1;
        re2c:define:YYSETCONDITION = 'condition = @@;';
        re2c:define:YYSETCONDITION:naked = 1;
        re2c:yyfill:enable = 0;
        re2c:eof = 0;

        <init> *                                        { return -1; }
        <init> $                                        { return  0; }

        <init> [/][/] .*                                { goto loop; }
        <init> [/][*]                   :=> comment

        <init> [ \t]+                                   { goto loop; }

        <init, comment> [\n]+                           { goto loop; }

        <comment> [^*\n]+ [*]*          :=> comment
        <comment> [^*\n]* [*]+          :=> comment
        <comment> [^*\n]* [*]+ [/]       => init        { goto loop; }

        <comment> *                     :=> comment
        <comment> $                                     { return -1; }
    */
}


int main(void)
{
    assert(!lex("/* hello, */ // world !"));

    return 0;
}

Compile:

re2c -W -Werror -c -o bug.c bug.re && gcc -o bug bug.c

@skvadrik
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skvadrik commented Jun 27, 2020

Are you talking about duplicate yyeof1 labels that are causing compilation error?

$ re2c -W -Werror -c -o bug.c bug.re && gcc -o bug bug.c
bug.re: In function ‘lex’:
bug.c:155:1: error: duplicate label ‘yyeof1’
  155 | yyeof1:
      | ^~~~~~
bug.c:98:1: note: previous definition of ‘yyeof1’ was here
   98 | yyeof1:
      | ^~~~~~

I fixed this: 5033918. Thanks for reporting.

Note that this is a different issue from the bug discussed above.

@jinscoe123
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jinscoe123 commented Jun 27, 2020

Wow, that was fast! And yes, the duplicate yyeof1 labels was the bug I was referring to.

Thank you!

@skvadrik
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skvadrik commented Jun 27, 2020

Note that this is a different issue from the bug discussed above.

@jinscoe123 Please ignore my comment, I myself got confused and thought this was a different bug. :)

@jinscoe123
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jinscoe123 commented Jun 27, 2020

No worries :)

netbsd-srcmastr pushed a commit to NetBSD/pkgsrc that referenced this issue Sep 20, 2020
2.0.3 (2020-08-22)
~~~~~~~~~~~~~~~~~~

- Fix issues when building re2c as a CMake subproject
  (`#302 <https://github.com/skvadrik/re2c/pull/302>`_:

- Final corrections in the SIMPA article "RE2C: A lexer generator based on
  lookahead-TDFA", https://doi.org/10.1016/j.simpa.2020.100027

2.0.2 (2020-08-08)
~~~~~~~~~~~~~~~~~~

- Enable re2go building by default.

- Package CMake files into release tarball.

2.0.1 (2020-07-29)
~~~~~~~~~~~~~~~~~~

- Updated version for CMake build system (forgotten in release 2.0).

- Added a short article about re2c for the Software Impacts journal.

2.0 (2020-07-20)
~~~~~~~~~~~~~~~~

- Added new code generation backend for Go and a new ``re2go`` program
  (`#272 <https://github.com/skvadrik/re2c/issues/272>`_: Go support).
  Added option ``--lang <c | go>``.

- Added CMake build system as an alternative to Autotools
  (`#275 <https://github.com/skvadrik/re2c/pull/275>`_:
  Add a CMake build system (thanks to ligfx),
  `#244 <https://github.com/skvadrik/re2c/issues/244>`_: Switching to CMake).

- Changes in generic API:

  + Removed primitives ``YYSTAGPD`` and ``YYMTAGPD``.
  + Added primitives ``YYSHIFT``, ``YYSHIFTSTAG``, ``YYSHIFTMTAG``
    that allow to express fixed tags in terms of generic API.
  + Added configurations ``re2c:api:style`` and ``re2c:api:sigil``.
  + Added named placeholders in interpolated configuration strings.

- Changes in reuse mode (``-r, --reuse`` option):

  + Do not reset API-related configurations in each `use:re2c` block
    (`#291 <https://github.com/skvadrik/re2c/issues/291>`_:
    Defines in rules block are not propagated to use blocks).
  + Use block-local options instead of last block options.
  + Do not accumulate options from rules/reuse blocks in whole-program options.
  + Generate non-overlapping YYFILL labels for reuse blocks.
  + Generate start label for each reuse block in storable state mode.

- Changes in start-conditions mode (``-c, --start-conditions`` option):

  + Allow to use normal (non-conditional) blocks in `-c` mode
    (`#263 <https://github.com/skvadrik/re2c/issues/263>`_:
    allow mixing conditional and non-conditional blocks with -c,
    `#296 <https://github.com/skvadrik/re2c/issues/296>`_:
    Conditions required for all lexers when using '-c' option).
  + Generate condition switch in every re2c block
    (`#295 <https://github.com/skvadrik/re2c/issues/295>`_:
    Condition switch generated for only one lexer per file).

- Changes in the generated labels:

  + Use ``yyeof`` label prefix instead of ``yyeofrule``.
  + Use ``yyfill`` label prefix instead of ``yyFillLabel``.
  + Decouple start label and initial label (affects label numbering).

- Removed undocumented configuration ``re2c🎏o``, ``re2c🎏output``.

- Changes in ``re2c🎏t``, ``re2c🎏type-header`` configuration:
  filename is now relative to the output file directory.

- Added option ``--case-ranges`` and configuration ``re2c🎏case-ranges``.

- Extended fixed tags optimization for the case of fixed-counter repetition.

- Fixed bugs related to EOF rule:

  + `#276 <https://github.com/skvadrik/re2c/issues/276>`_:
    Example 01_fill.re in docs is broken
  + `#280 <https://github.com/skvadrik/re2c/issues/280>`_:
    EOF rules with multiple blocks
  + `#284 <https://github.com/skvadrik/re2c/issues/284>`_:
    mismatched YYBACKUP and YYRESTORE
    (Add missing fallback states with EOF rule)

- Fixed miscellaneous bugs:

  + `#286 <https://github.com/skvadrik/re2c/issues/286>`_:
    Incorrect submatch values with fixed-length trailing context.
  + `#297 <https://github.com/skvadrik/re2c/issues/297>`_:
    configure error on ubuntu 18.04 / cmake 3.10

- Changed bootstrap process (require explicit configuration flags and a path to
  re2c executable to regenerate the lexers).

- Added internal options ``--posix-prectable <naive | complex>``.

- Added debug option ``--dump-dfa-tree``.

- Major revision of the paper "Efficient POSIX submatch extraction on NFA".

----
1.3x
----

1.3 (2019-12-14)
~~~~~~~~~~~~~~~~

- Added option: ``--stadfa``.

- Added warning: ``-Wsentinel-in-midrule``.

- Added generic API primitives:

  + ``YYSTAGPD``
  + ``YYMTAGPD``

- Added configurations:

  + ``re2c:sentinel = 0;``
  + ``re2c:define:YYSTAGPD = "YYSTAGPD";``
  + ``re2c:define:YYMTAGPD = "YYMTAGPD";``

- Worked on reproducible builds
  (`#258 <https://github.com/skvadrik/re2c/pull/258>`_:
  Make the build reproducible).

----
1.2x
----

1.2.1 (2019-08-11)
~~~~~~~~~~~~~~~~~~

- Fixed bug `#253 <https://github.com/skvadrik/re2c/issues/253>`_:
  re2c should install unicode_categories.re somewhere.

- Fixed bug `#254 <https://github.com/skvadrik/re2c/issues/254>`_:
  Turn off re2c:eof = 0.

1.2 (2019-08-02)
~~~~~~~~~~~~~~~~

- Added EOF rule ``$`` and configuration ``re2c:eof``.

- Added ``/*!include:re2c ... */`` directive and ``-I`` option.

- Added ``/*!header:re2c:on*/`` and ``/*!header:re2c:off*/`` directives.

- Added ``--input-encoding <ascii | utf8>`` option.

  + `#237 <https://github.com/skvadrik/re2c/issues/237>`_:
    Handle non-ASCII encoded characters in regular expressions
  + `#250 <https://github.com/skvadrik/re2c/issues/250>`_
    UTF8 enoding

- Added include file with a list of definitions for Unicode character classes.

  + `#235 <https://github.com/skvadrik/re2c/issues/235>`_:
    Unicode character classes

- Added ``--location-format <gnu | msvc>`` option.

  + `#195 <https://github.com/skvadrik/re2c/issues/195>`_:
    Please consider using Gnu format for error messages

- Added ``--verbose`` option that prints "success" message if re2c exits
  without errors.

- Added configurations for options:

  + ``-o --output`` (specify output file)
  + ``-t --type-header`` (specify header file)

- Removed configurations for internal/debug options.

- Extended ``-r`` option: allow to mix multiple ``/*!rules:re2c*/``,
  ``/*!use:re2c*/`` and ``/*!re2c*/`` blocks.

  + `#55 <https://github.com/skvadrik/re2c/issues/55>`_:
    allow standard re2c blocks in reuse mode

- Fixed ``-F --flex-support`` option: parsing and operator precedence.

  + `#229 <https://github.com/skvadrik/re2c/issues/229>`_:
    re2c option -F (flex syntax) broken
  + `#242 <https://github.com/skvadrik/re2c/issues/242>`_:
    Operator precedence with --flex-syntax is broken

- Changed difference operator ``/`` to apply before encoding expansion of
  operands.

  + `#236 <https://github.com/skvadrik/re2c/issues/236>`_:
    Support range difference with variable-length encodings

- Changed output generation of output file to be atomic.

  + `#245 <https://github.com/skvadrik/re2c/issues/245>`_:
    re2c output is not atomic

- Authored research paper "Efficient POSIX Submatch Extraction on NFA"
  together with Dr Angelo Borsotti.

- Added experimental libre2c library (``--enable-libs`` configure option) with
  the following algorithms:

  + TDFA with leftmost-greedy disambiguation
  + TDFA with POSIX disambiguation (Okui-Suzuki algorithm)
  + TNFA with leftmost-greedy disambiguation
  + TNFA with POSIX disambiguation (Okui-Suzuki algorithm)
  + TNFA with lazy POSIX disambiguation (Okui-Suzuki algorithm)
  + TNFA with POSIX disambiguation (Kuklewicz algorithm)
  + TNFA with POSIX disambiguation (Cox algorithm)

- Added debug subsystem (``--enable-debug`` configure option) and new debug
  options:

  + ``-dump-cfg`` (dump control flow graph of tag variables)
  + ``-dump-interf`` (dump interference table of tag variables)
  + ``-dump-closure-stats`` (dump epsilon-closure statistics)

- Added internal options:

  + ``--posix-closure <gor1 | gtop>`` (switch between shortest-path algorithms
    used for the construction of POSIX closure)

- Fixed a number of crashes found by American Fuzzy Lop fuzzer:

  + `#226 <https://github.com/skvadrik/re2c/issues/226>`_,
    `#227 <https://github.com/skvadrik/re2c/issues/227>`_,
    `#228 <https://github.com/skvadrik/re2c/issues/228>`_,
    `#231 <https://github.com/skvadrik/re2c/issues/231>`_,
    `#232 <https://github.com/skvadrik/re2c/issues/232>`_,
    `#233 <https://github.com/skvadrik/re2c/issues/233>`_,
    `#234 <https://github.com/skvadrik/re2c/issues/234>`_,
    `#238 <https://github.com/skvadrik/re2c/issues/238>`_

- Fixed handling of newlines:

  + correctly parse multi-character newlines CR LF in ``#line`` directives
  + consistently convert all newlines in the generated file to Unix-style LF

- Changed default tarball format from .gz to .xz.

  + `#221 <https://github.com/skvadrik/re2c/issues/221>`_:
    big source tarball

- Fixed a number of other bugs and resolved issues:

  + `#2 <https://github.com/skvadrik/re2c/issues/2>`_: abort
  + `#6 <https://github.com/skvadrik/re2c/issues/6>`_: segfault
  + `#10 <https://github.com/skvadrik/re2c/issues/10>`_:
    lessons/002_upn_calculator/calc_002 doesn't produce a useful example program
  + `#44 <https://github.com/skvadrik/re2c/issues/44>`_:
    Access violation when translating the attached file
  + `#49 <https://github.com/skvadrik/re2c/issues/49>`_:
    wildcard state \000 rules makes lexer behave weard
  + `#98 <https://github.com/skvadrik/re2c/issues/98>`_:
    Transparent handling of #line directives in input files
  + `#104 <https://github.com/skvadrik/re2c/issues/104>`_:
    Improve const-correctness
  + `#105 <https://github.com/skvadrik/re2c/issues/105>`_:
    Conversion of pointer parameters into references
  + `#114 <https://github.com/skvadrik/re2c/issues/114>`_:
    Possibility of fixing bug 2535084
  + `#120 <https://github.com/skvadrik/re2c/issues/120>`_:
    condition consisting of default rule only is ignored
  + `#167 <https://github.com/skvadrik/re2c/issues/167>`_:
    Add word boundary support
  + `#168 <https://github.com/skvadrik/re2c/issues/168>`_:
    Wikipedia's article on re2c
  + `#180 <https://github.com/skvadrik/re2c/issues/180>`_:
    Comment syntax?
  + `#182 <https://github.com/skvadrik/re2c/issues/182>`_:
    yych being set by YYPEEK () and then not used
  + `#196 <https://github.com/skvadrik/re2c/issues/196>`_:
    Implicit type conversion warnings
  + `#198 <https://github.com/skvadrik/re2c/issues/198>`_:
    no match for ‘operator!=’ in ‘i != std::vector<_Tp, _Alloc>::rend() [with _Tp = re2c::bitmap_t, _Alloc = std::allocator<re2c::bitmap_t>]()’
  + `#210 <https://github.com/skvadrik/re2c/issues/210>`_:
    How to build re2c in windows?
  + `#215 <https://github.com/skvadrik/re2c/issues/215>`_:
    A memory read overrun issue in s_to_n32_unsafe.cc
  + `#220 <https://github.com/skvadrik/re2c/issues/220>`_:
    src/dfa/dfa.h: simplify constructor to avoid g++-3.4 bug
  + `#223 <https://github.com/skvadrik/re2c/issues/223>`_:
    Fix typo
  + `#224 <https://github.com/skvadrik/re2c/issues/224>`_:
    src/dfa/closure_posix.cc: pack() tweaks
  + `#225 <https://github.com/skvadrik/re2c/issues/225>`_:
    Documentation link is broken in libre2c/README
  + `#230 <https://github.com/skvadrik/re2c/issues/230>`_:
    Changes for upcoming Travis' infra migration
  + `#239 <https://github.com/skvadrik/re2c/issues/239>`_:
    Push model example has wrong re2c invocation, breaks guide
  + `#241 <https://github.com/skvadrik/re2c/issues/241>`_:
    Guidance on how to use re2c for full-duplex command & response protocol
  + `#243 <https://github.com/skvadrik/re2c/issues/243>`_:
    A code generated for period (.) requires 4 bytes
  + `#246 <https://github.com/skvadrik/re2c/issues/246>`_:
    Please add a license to this repo
  + `#247 <https://github.com/skvadrik/re2c/issues/247>`_:
    Build failure on current Cygwin, probably caused by force-fed c++98 mode
  + `#248 <https://github.com/skvadrik/re2c/issues/248>`_:
    distcheck still looks for README
  + `#251 <https://github.com/skvadrik/re2c/issues/251>`_:
    Including what you use is find, but not without inclusion guards

- Updated documentation and website.
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