Re: [PATCH] xcoffread.c: Fix -Werror=dangling-pointer= issue with main_subfile.

[Mark Wielaard <mark@klomp.org>]

Hi Simon,

On Mon, May 01, 2023 at 09:53:39AM -0400, Simon Marchi wrote:
> > Fix this by making main_subfile file static that is allocated and
> > deallocated together with inclTable and allocate_include_entry and
> > xcoff_symfile_finish. Adjust the use of main_subfile in
> > process_linenos to take a pointer to the struct subfile.
> 
> I'm not familiar at all with this code, but your change looks reasonable
> to me.

I am also not familiar with this code, but noticed that the
fedora-latest and suse-tumbleweed buildbots started failing when they
upgraded to GCC 13.1. The simplest solution seemed to be to give both
structures the same lifetime. I didn't see any regressions with this
fix (but don't actually know if the testsuite triggers this code).

> Some style comments:
> 
> > ---
> >  gdb/xcoffread.c | 24 +++++++++++++-----------
> >  1 file changed, 13 insertions(+), 11 deletions(-)
> > 
> > diff --git a/gdb/xcoffread.c b/gdb/xcoffread.c
> > index d71127b40f6..db6f2df6c0a 100644
> > --- a/gdb/xcoffread.c
> > +++ b/gdb/xcoffread.c
> > @@ -498,6 +498,9 @@ static int inclIndx;		/* last entry to table */
> >  static int inclLength;		/* table length */
> >  static int inclDepth;		/* nested include depth */
> >  
> > +/* subfile structure for the main compilation unit.  */
> > +static struct subfile *main_subfile;
> 
> Remove "struct".

OK.
 
> > @@ -548,6 +551,7 @@ allocate_include_entry (void)
> >        inclTable = XCNEWVEC (InclTable, INITIAL_INCLUDE_TABLE_LENGTH);
> >        inclLength = INITIAL_INCLUDE_TABLE_LENGTH;
> >        inclIndx = 0;
> > +      main_subfile = new (struct subfile);
> 
> "new subfile" would be enough.

OK.

> >    for (int ii = 0; ii < inclIndx; ++ii)
> >      {
> > -      if (inclTable[ii].subfile != ((struct subfile *) &main_subfile)
> > +      if (inclTable[ii].subfile != ((struct subfile *) main_subfile)
> 
> Since you touch this line, I think you could remove the cast.
> main_subfile is already of the right type.

Right.

Will sent v2 with those changes.

Thanks,

Mark