Re: [C++ Patch] [PR c++/88146] do not crash synthesizing inherited ctor(...)

[Christophe Lyon <christophe.lyon@linaro.org>]

On Sat, 15 Dec 2018 at 23:11, Jason Merrill <jason@redhat.com> wrote:
>
> On Fri, Dec 14, 2018 at 6:05 PM Alexandre Oliva <aoliva@redhat.com> wrote:
> >
> > On Dec 14, 2018, Jason Merrill <jason@redhat.com> wrote:
> >
> > > Let's move the initialization of "fields" inside the 'then' block here
> > > with the initialization of "cvquals", rather than clear it in the
> > > 'else'.
> >
> > We'd still have to NULL-initialize it somewhere, so I'd rather just move
> > the entire loop into the conditional, and narrow the scope of variables
> > only used within the loop, like this.  The full patch below is very hard
> > to read because of the reindentation, so here's a diff -b.
> >
> > diff --git a/gcc/cp/method.c b/gcc/cp/method.c
> > index fd023e200538..17404a65b0fd 100644
> > --- a/gcc/cp/method.c
> > +++ b/gcc/cp/method.c
> > @@ -675,12 +675,9 @@ do_build_copy_constructor (tree fndecl)
> >      }
> >    else
> >      {
> > -      tree fields = TYPE_FIELDS (current_class_type);
> >        tree member_init_list = NULL_TREE;
> > -      int cvquals = cp_type_quals (TREE_TYPE (parm));
> >        int i;
> >        tree binfo, base_binfo;
> > -      tree init;
> >        vec<tree, va_gc> *vbases;
> >
> >        /* Initialize all the base-classes with the parameter converted
> > @@ -704,15 +701,18 @@ do_build_copy_constructor (tree fndecl)
> >                                                 inh, member_init_list);
> >         }
> >
> > -      for (; fields; fields = DECL_CHAIN (fields))
> > +      if (!inh)
> > +       {
> > +         int cvquals = cp_type_quals (TREE_TYPE (parm));
> > +
> > +         for (tree fields = TYPE_FIELDS (current_class_type);
> > +              fields; fields = DECL_CHAIN (fields))
> >             {
> >               tree field = fields;
> >               tree expr_type;
> >
> >               if (TREE_CODE (field) != FIELD_DECL)
> >                 continue;
> > -         if (inh)
> > -           continue;
> >
> >               expr_type = TREE_TYPE (field);
> >               if (DECL_NAME (field))
> > @@ -742,7 +742,7 @@ do_build_copy_constructor (tree fndecl)
> >                   expr_type = cp_build_qualified_type (expr_type, quals);
> >                 }
> >
> > -         init = build3 (COMPONENT_REF, expr_type, parm, field, NULL_TREE);
> > +             tree init = build3 (COMPONENT_REF, expr_type, parm, field, NULL_TREE);
> >               if (move_p && !TYPE_REF_P (expr_type)
> >                   /* 'move' breaks bit-fields, and has no effect for scalars.  */
> >                   && !scalarish_type_p (expr_type))
> > @@ -751,6 +751,8 @@ do_build_copy_constructor (tree fndecl)
> >
> >               member_init_list = tree_cons (field, init, member_init_list);
> >             }
> > +       }
> > +
> >        finish_mem_initializers (member_init_list);
> >      }
> >  }
> > @@ -891,6 +893,7 @@ synthesize_method (tree fndecl)
> >
> >    /* Reset the source location, we might have been previously
> >       deferred, and thus have saved where we were first needed.  */
> > +  if (!DECL_INHERITED_CTOR (fndecl))
> >      DECL_SOURCE_LOCATION (fndecl)
> >        = DECL_SOURCE_LOCATION (TYPE_NAME (DECL_CONTEXT (fndecl)));
> >
> >
> > Is this OK too?  (pending regstrapping)
>
> Yes, thanks.
>

Hi,

The new test inh-ctor32.C fails on arm:
FAIL:    g++.dg/cpp0x/inh-ctor32.C  -std=c++14  (test for warnings, line 208)
FAIL:    g++.dg/cpp0x/inh-ctor32.C  -std=c++17  (test for warnings, line 208)

The log has:

/gcc/testsuite/g++.dg/cpp0x/inh-ctor32.C: In instantiation of
'constexpr derived_ctor::inherited_derived_ctor::constexpr_noninherited_ctor::bor::bor(T
...) [with T = {int, int}]':
/gcc/testsuite/g++.dg/cpp0x/inh-ctor32.C:206:13:   required from
'constexpr derived_ctor::inherited_derived_ctor::constexpr_noninherited_ctor::bar::bar(T
...) [with T = {int, int}][inherited from
derived_ctor::inherited_derived_ctor::constexpr_noninherited_ctor::bor]'
/gcc/testsuite/g++.dg/cpp0x/inh-ctor32.C:208:42:   required from here

Christophe


> Jason