[Bug c++/104623] New: [11/12 Regression] ICE in cp_parser_skip_to_pragma_eol, at cp/parser.cc:4107

[Bug c++/104623] New: [11/12 Regression] ICE in cp_parser_skip_to_pragma_eol, at cp/parser.cc:4107

[gscfq@t-online.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104623

            Bug ID: 104623
           Summary: [11/12 Regression] ICE in
                    cp_parser_skip_to_pragma_eol, at cp/parser.cc:4107
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gscfq@t-online.de
  Target Milestone: ---

Started between 20200712 and 20200719 :


$ cat z1.cc
void f ()
{
  struct __attribute__() a
  #pragma omp task
}


$ g++-12-20220220 -c z1.cc -fopenmp
z1.cc: In function 'void f()':
z1.cc:5:1: internal compiler error: in cp_parser_skip_to_pragma_eol, at
cp/parser.cc:4107
    5 | }
      | ^
0x8e6af9 cp_parser_skip_to_pragma_eol
        ../../gcc/cp/parser.cc:4107
0x8e6e12 cp_parser_skip_to_end_of_statement
        ../../gcc/cp/parser.cc:394q3
0x8fc7b4 cp_parser_gnu_attributes_opt
        ../../gcc/cp/parser.cc:28676
0x92749b cp_parser_elaborated_type_specifier
        ../../gcc/cp/parser.cc:20341
0x908cf3 cp_parser_type_specifier
        ../../gcc/cp/parser.cc:19375
0x909e06 cp_parser_decl_specifier_seq
        ../../gcc/cp/parser.cc:15911
0x90aa81 cp_parser_simple_declaration
        ../../gcc/cp/parser.cc:15159
0x90c779 cp_parser_declaration_statement
        ../../gcc/cp/parser.cc:14367
0x90ce9b cp_parser_statement
        ../../gcc/cp/parser.cc:12452
0x90def4 cp_parser_statement_seq_opt
        ../../gcc/cp/parser.cc:12856
0x90dfd7 cp_parser_compound_statement
        ../../gcc/cp/parser.cc:12808
0x934560 cp_parser_function_body
        ../../gcc/cp/parser.cc:25062
0x934560 cp_parser_ctor_initializer_opt_and_function_body
        ../../gcc/cp/parser.cc:25113
0x934bda cp_parser_function_definition_after_declarator
        ../../gcc/cp/parser.cc:31243
0x935e64 cp_parser_function_definition_from_specifiers_and_declarator
        ../../gcc/cp/parser.cc:31159
0x935e64 cp_parser_init_declarator
        ../../gcc/cp/parser.cc:22584
0x90abe2 cp_parser_simple_declaration
        ../../gcc/cp/parser.cc:15286
0x93d40e cp_parser_declaration
        ../../gcc/cp/parser.cc:14972
0x93df8d cp_parser_translation_unit
        ../../gcc/cp/parser.cc:5012
0x93df8d c_parse_file()
        ../../gcc/cp/parser.cc:48051

[Bug c++/104623] [11/12 Regression] ICE in cp_parser_skip_to_pragma_eol, at cp/parser.cc:4107

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104623

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |11.3

[Bug c++/104623] [11/12 Regression] ICE in cp_parser_skip_to_pragma_eol, at cp/parser.cc:4107

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104623

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2

[Bug c++/104623] [11/12 Regression] ICE in cp_parser_skip_to_pragma_eol, at cp/parser.cc:4107

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104623

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2022-02-22
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
                 CC|                            |mpolacek at gcc dot gnu.org

--- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Started with r11-2106-gf0d0be62db5ba030283fa8189211830d09dfb467

[Bug c++/104623] [11/12 Regression] ICE in cp_parser_skip_to_pragma_eol, at cp/parser.cc:4107

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104623

--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Looks like a missing CPP_PRAGMA_EOL.

[Bug c++/104623] [11/12 Regression] ICE in cp_parser_skip_to_pragma_eol, at cp/parser.cc:4107

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104623

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 52607
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52607&action=edit
gcc12-pr104623.patch

The problem is that the function purges the tokens, from the token after
CPP_PRAGMA until CPP_PRAGMA_EOL (the latter inclusive).  But CPP_PRAGMA is not
purged.  So, next time we tentatively parse it we ICE because CPP_PRAGMA isn't
followed by CPP_PRAGMA_EOL anymore (because purged tokens are ignored).
I have tried various things, purging also the pragma_tok token or changing
second argument of cp_parser_skip_to_pragma_eol to NULL in
cp_parser_skip_to_end_of_statement and
cp_parser_skip_to_end_of_block_or_statement but both regressed various
testcases.
This at least in quick check-g++ testing didn't regress anything.

[Bug c++/104623] [11/12 Regression] ICE in cp_parser_skip_to_pragma_eol, at cp/parser.cc:4107

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104623

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:efd1582926f3278a5e57ebab7d87fc870f06ecea

commit r12-7652-gefd1582926f3278a5e57ebab7d87fc870f06ecea
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue Mar 15 09:15:27 2022 +0100

    c++: Fix up cp_parser_skip_to_pragma_eol [PR104623]

    We ICE on the following testcase, because we tentatively parse it multiple
    times and the erroneous attribute syntax results in
    cp_parser_skip_to_end_of_statement, which when seeing CPP_PRAGMA (can be
    any deferred one, OpenMP/OpenACC/ivdep etc.) it calls
    cp_parser_skip_to_pragma_eol, which calls cp_lexer_purge_tokens_after.
    That call purges all the tokens from CPP_PRAGMA until CPP_PRAGMA_EOL,
    excluding the initial CPP_PRAGMA though (but including the final
    CPP_PRAGMA_EOL).  This means the second time we parse this, we see
    CPP_PRAGMA with no tokens after it from the pragma, most importantly
    not the CPP_PRAGMA_EOL, so either if it is the last pragma in the TU,
    we ICE, or if there are other pragmas we treat everything in between
    as a pragma.

    I've tried various things, including making the CPP_PRAGMA token
    itself also purged, or changing the cp_parser_skip_to_end_of_statement
    (and cp_parser_skip_to_end_of_block_or_statement) to call it with
    NULL instead of token, so that this purging isn't done there,
    but each patch resulted in lots of regressions.
    But removing the purging altogether surprisingly doesn't regress anything,
    and I think it is the right thing, if we e.g. parse tentatively, why can't
    we parse the pragma multiple times or at least skip over it?

    2022-03-15  Jakub Jelinek  <jakub@redhat.com>

            PR c++/104623
            * parser.cc (cp_parser_skip_to_pragma_eol): Don't purge any tokens.

            * g++.dg/gomp/pr104623.C: New test.

[Bug c++/104623] [11 Regression] ICE in cp_parser_skip_to_pragma_eol, at cp/parser.cc:4107

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104623

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[11/12 Regression] ICE in   |[11 Regression] ICE in
                   |cp_parser_skip_to_pragma_eo |cp_parser_skip_to_pragma_eo
                   |l, at cp/parser.cc:4107     |l, at cp/parser.cc:4107

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Fixed on the trunk so far.
It is ice-on-invalid-code, so I'm a hesistant to backport this.

[Bug c++/104623] [11 Regression] ICE in cp_parser_skip_to_pragma_eol, at cp/parser.cc:4107

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104623

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|11.3                        |11.4

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 11.3 is being released, retargeting bugs to GCC 11.4.

[Bug c++/104623] [11 Regression] ICE in cp_parser_skip_to_pragma_eol, at cp/parser.cc:4107

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104623

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|11.4                        |11.5

--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 11.4 is being released, retargeting bugs to GCC 11.5.