[Bug modula2/108557] New: Stuck compilation for empty file

[Bug modula2/108557] New: Stuck compilation for empty file

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108557

            Bug ID: 108557
           Summary: Stuck compilation for empty file
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: modula2
          Assignee: gaius at gcc dot gnu.org
          Reporter: marxin at gcc dot gnu.org
  Target Milestone: ---

Noticed that during reduction of a test-case:

$ echo '' > x.mod
$ timeout 1 /dev/shm/objdir/./gcc/cc1gm2 x.mod
$ echo $?
124

[Bug modula2/108557] Stuck compilation for empty file

[gaius at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108557

Gaius Mulley <gaius at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2023-01-26
     Ever confirmed|0                           |1

--- Comment #1 from Gaius Mulley <gaius at gcc dot gnu.org> ---
Thanks, indeed replicated and confirmed.

[Bug modula2/108557] Stuck compilation for empty file

[gaius at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108557

Gaius Mulley <gaius at gcc dot gnu.org> changed:

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

--- Comment #2 from Gaius Mulley <gaius at gcc dot gnu.org> ---
Created attachment 54361
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=54361&action=edit
Proposed fix

I believe this fixes the bug.

PR-108557 Stuck compilation for empty file

Trying to compile an empty file causes cc1gm2 to hang.
The bug was that M2LexBuf.mod called m2flex.GetToken after
an eof token was seen which resulted in m2flex attempting
to read from stdin.  The bug fix detects eof per file and
blocks a subsequent to m2flex.GetToken.

gcc/m2/ChangeLog:

        * gm2-compiler/M2Comp.mod:  Import MetaString0.
        (ExamineCompilationUnit): New variable Message.
        Create and format error string.
        * gm2-compiler/M2LexBuf.mod: New variable SeenEof.
        (GetNonEofToken): New procedure.
        (Init): Set SeenEof to FALSE.
        (GetToken): Use GetNonEofToken instead of calls to
        m2flex.GetToken and GetToken.
        (AddTok): Detect eoftok and set SeenEof.

gcc/testsuite/ChangeLog:

        * gm2/pim/fail/empty.mod: New test.

[Bug modula2/108557] Stuck compilation for empty file

[gaius at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108557

Gaius Mulley <gaius at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|ASSIGNED                    |RESOLVED

--- Comment #3 from Gaius Mulley <gaius at gcc dot gnu.org> ---
[gcc r13-5463] PR-108557 Stuck compilation for empty file.

git pushed (and next time I'll get the PR syntax correct)