Re: Bug in coerce_template_parms (patch)

[Kriang Lerdsuwanakij <lerdsuwa at scf-fs dot usc dot edu>]

Sorry, the previous patch is broken...  I'll look at that again
tomorrow.

Kriang

Kriang Lerdsuwanakij wrote:
> 
> Martin von Loewis wrote:
> >
> > Did anybody notice problems in template parameter resolution?
> > There seems to be a problem in coerce_template_parms, exposed e.g.
> > by ttp26.C. Around line 1896, it checks whether the arglist is
> > a vector. If it isn't, it treats it as a list.
> >
> > Now, there is another check whether nargs==nparms. In ttp26.C, this is
> > not the case because there are default parameters.  So the check
> > fails, but the arguments are still passed as a vector. This goes
> > unnoticed, as the code retrieves the argument using TREE_VALUE, which
> > happens to be the right offset. I'm sure one can construct examples
> > where the code breaks, though.
> >
> 
> > I found this by putting an assertion into TREE_VALUE that the node
> > really is a TREE_LIST. I don't have a test case for this specific
> > code. If nobody can reproduce the problem, I can try to find one.  For
> > ttp26.C, the problem manifests in the 20th invocation of
> > coerce_template_parms.
> >
> > Thanks,
> > Martin
> 
> Thanks for pointing that out.  It's a bug (and my fault :( ).  Below is
> a small patch that fixes that.  When arglist is a vector with less
> elements than required, it should be handled by inside the
> 'else if (is_tmpl_parm && i < nargs)' case.  is_tmpl_parm is an
> indicator that vector may not satisfy the nargs==nparms condition.
> 
> Kriang
> 
> ===========================
> 
>         * pt.c (coerce_template_parms): Fix thinko.
> 
> *** pt.c        1998/03/10 10:01:37     1.6
> --- pt.c        1998/03/17 04:21:51
> *************** coerce_template_parms (parms, arglist, i
> *** 1904,1910 ****
>           tree arg;
>           tree parm = TREE_VEC_ELT (parms, i);
> 
> !         if (arglist)
>             {
>               arg = arglist;
>               arglist = TREE_CHAIN (arglist);
> --- 1904,1910 ----
>           tree arg;
>           tree parm = TREE_VEC_ELT (parms, i);
> 
> !         if (arglist && TREE_CODE (arglist) == TREE_LIST)
>             {
>               arg = arglist;
>               arglist = TREE_CHAIN (arglist);