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Re: [PATCH] Fix PR c++/70332 (ICE due to aggregate initialization of NSDMI)
- From: Patrick Palka <patrick at parcs dot ath dot cx>
- To: Jason Merrill <jason at redhat dot com>
- Cc: Patrick Palka <patrick at parcs dot ath dot cx>, GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 23 Mar 2016 09:21:23 -0400 (EDT)
- Subject: Re: [PATCH] Fix PR c++/70332 (ICE due to aggregate initialization of NSDMI)
- Authentication-results: sourceware.org; auth=none
- References: <1458682553-20882-1-git-send-email-patrick at parcs dot ath dot cx> <56F1C07E dot 9040302 at redhat dot com> <CA+C-WL86jp0WLYrS+GikPiN5H-bH9Sa0OXmjaUZYq3qnMMAZuA at mail dot gmail dot com> <CA+C-WL9fEERNQN1gnJJarQk6ivffOmMkSKhGrBztQAn5pcFgaw at mail dot gmail dot com> <56F292FA dot 5010200 at redhat dot com>
On Wed, 23 Mar 2016, Jason Merrill wrote:
> On 03/22/2016 07:12 PM, Patrick Palka wrote:
> > On Tue, Mar 22, 2016 at 6:12 PM, Patrick Palka <patrick@parcs.ath.cx> wrote:
> > > On Tue, Mar 22, 2016 at 6:00 PM, Jason Merrill <jason@redhat.com> wrote:
> > > > On 03/22/2016 05:35 PM, Patrick Palka wrote:
> > > > >
> > > > > + if (cp_unevaluated_operand == 0
> > > >
> > > >
> > > > Why check this here?
> > >
> > > Just so that the change doesn't affect the behavior of tsubst_decl()
> > > when cp_unevaluated_operand != 0. Presumably the existing code (10
> > > lines below) handles that case just fine.
> >
> > Turns out that without the check we can trigger the cxx_dialect >=
> > cxx14 assert because in c++11 mode we can reach the assert through
> > get_defaulted_eh_spec() which increments cp_unevaluated_operand and
> > then calls get_nsdmi (..., /*in_ctor=*/false) causing
> > current_class_ref to get set to a PLACEHOLDER_EXPR.
> >
> > So for example g++.dg/cpp0x/nsdmi-template2.C regresses with an ICE.
> > So it seems the cp_unevaluated_operand != 0 check is necessary as long
> > as the assert stays.
> >
> > There are no regressions if both the cp_unevaluated_operand check and
> > the assert are removed however.
>
> I think that's my preference.
>
> Jason
>
>
>
Done. Does this version look OK to commit after bootstrap + regtesting?
gcc/cp/ChangeLog:
PR c++/70332
* pt.c (tsubst_copy) [PARM_DECL]: Handle the use of 'this' in an
NSDMI that's part of an aggregrate initialization.
gcc/testsuite/ChangeLog:
PR c++/70332
* g++.dg/cpp1y/nsdmi-aggr5.C: New test.
---
gcc/cp/pt.c | 9 ++++++---
gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr5.C | 24 ++++++++++++++++++++++++
2 files changed, 30 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr5.C
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index ebfc45b..231d112 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -13877,10 +13877,13 @@ tsubst_copy (tree t, tree args, tsubst_flags_t complain, tree in_decl)
if (r == NULL_TREE)
{
- /* We get here for a use of 'this' in an NSDMI. */
+ /* We get here for a use of 'this' in an NSDMI as part of a
+ constructor call or as part of an aggregate initialization. */
if (DECL_NAME (t) == this_identifier
- && current_function_decl
- && DECL_CONSTRUCTOR_P (current_function_decl))
+ && ((current_function_decl
+ && DECL_CONSTRUCTOR_P (current_function_decl))
+ || (current_class_ref
+ && TREE_CODE (current_class_ref) == PLACEHOLDER_EXPR)))
return current_class_ptr;
/* This can happen for a parameter name used later in a function
diff --git a/gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr5.C b/gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr5.C
new file mode 100644
index 0000000..fe377c3
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr5.C
@@ -0,0 +1,24 @@
+// PR c++/70332
+// { dg-do run { target c++14 } }
+
+template <class T>
+struct C
+{
+ T m;
+ T *n = &m;
+};
+
+C<int> c { };
+
+int
+main ()
+{
+ *c.n = 5;
+ if (c.m != 5)
+ __builtin_abort ();
+
+ C<int> d { 10 };
+ *d.n = *d.n + 1;
+ if (d.m != 11)
+ __builtin_abort ();
+}
--
2.8.0.rc3.27.gade0865