* C++ PATCH for c++/86063, ICE with attribute with pack expansion
@ 2018-06-06 21:18 Marek Polacek
2018-06-11 19:00 ` Jason Merrill
0 siblings, 1 reply; 6+ messages in thread
From: Marek Polacek @ 2018-06-06 21:18 UTC (permalink / raw)
To: GCC Patches, Jason Merrill
We crash on this testcase containing a bogus attribute, because
cp_check_const_attributes accessed TREE_VALUE of a tree that happened to be
expr_pack_expansion. Since here we're merely trying to evaluate constexpr
arguments, I thought we could skip such bogus arguments.
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2018-06-06 Marek Polacek <polacek@redhat.com>
PR c++/86063
* decl2.c (cp_check_const_attributes): Skip trees that are not
TREE_LISTs.
* g++.dg/cpp0x/gen-attrs-65.C: New test.
diff --git gcc/cp/decl2.c gcc/cp/decl2.c
index 2cef9c750ed..35d8e423397 100644
--- gcc/cp/decl2.c
+++ gcc/cp/decl2.c
@@ -1386,7 +1386,8 @@ cp_check_const_attributes (tree attributes)
for (attr = attributes; attr; attr = TREE_CHAIN (attr))
{
tree arg;
- for (arg = TREE_VALUE (attr); arg; arg = TREE_CHAIN (arg))
+ for (arg = TREE_VALUE (attr); arg && TREE_CODE (arg) == TREE_LIST;
+ arg = TREE_CHAIN (arg))
{
tree expr = TREE_VALUE (arg);
if (EXPR_P (expr))
diff --git gcc/testsuite/g++.dg/cpp0x/gen-attrs-65.C gcc/testsuite/g++.dg/cpp0x/gen-attrs-65.C
index e69de29bb2d..1d2b2f04e7a 100644
--- gcc/testsuite/g++.dg/cpp0x/gen-attrs-65.C
+++ gcc/testsuite/g++.dg/cpp0x/gen-attrs-65.C
@@ -0,0 +1,7 @@
+// PR c++/86063
+// { dg-do compile { target c++11 } }
+
+template <class... T>
+struct S {
+ [[foobar(alignof(T))...]] char t; // { dg-warning "attribute directive ignored" }
+};
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: C++ PATCH for c++/86063, ICE with attribute with pack expansion
2018-06-06 21:18 C++ PATCH for c++/86063, ICE with attribute with pack expansion Marek Polacek
@ 2018-06-11 19:00 ` Jason Merrill
2018-06-14 16:51 ` Marek Polacek
0 siblings, 1 reply; 6+ messages in thread
From: Jason Merrill @ 2018-06-11 19:00 UTC (permalink / raw)
To: Marek Polacek; +Cc: GCC Patches
On Wed, Jun 6, 2018 at 5:18 PM, Marek Polacek <polacek@redhat.com> wrote:
> We crash on this testcase containing a bogus attribute, because
> cp_check_const_attributes accessed TREE_VALUE of a tree that happened to be
> expr_pack_expansion. Since here we're merely trying to evaluate constexpr
> arguments, I thought we could skip such bogus arguments.
Hmm, attributes should always be a TREE_LIST, lots of places assume
that. Why isn't the pack expansion wrapped in a TREE_LIST?
Jason
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: C++ PATCH for c++/86063, ICE with attribute with pack expansion
2018-06-11 19:00 ` Jason Merrill
@ 2018-06-14 16:51 ` Marek Polacek
2018-06-14 16:59 ` Jason Merrill
0 siblings, 1 reply; 6+ messages in thread
From: Marek Polacek @ 2018-06-14 16:51 UTC (permalink / raw)
To: Jason Merrill; +Cc: GCC Patches
On Mon, Jun 11, 2018 at 03:00:04PM -0400, Jason Merrill wrote:
> On Wed, Jun 6, 2018 at 5:18 PM, Marek Polacek <polacek@redhat.com> wrote:
> > We crash on this testcase containing a bogus attribute, because
> > cp_check_const_attributes accessed TREE_VALUE of a tree that happened to be
> > expr_pack_expansion. Since here we're merely trying to evaluate constexpr
> > arguments, I thought we could skip such bogus arguments.
>
> Hmm, attributes should always be a TREE_LIST, lots of places assume
> that. Why isn't the pack expansion wrapped in a TREE_LIST?
I believe you did that on purpose. There pack comes from
cp_parser_std_attribute_list. We could wrap it into a TREE_LIST, but then
tsubst_attribute would have to be tweaked to handle the pack expansion
correctly. Since this is invalid code, it didn't seem worth it. Normally
we remove the attribute in save_template_attributes:
if (processing_template_decl)
{
if (check_for_bare_parameter_packs (attributes))
return;
save_template_attributes (&attributes, decl, flags);
}
cp_check_const_attributes (attributes);
so attributes is null after calling cp_check_const_attributes. But this test
is invalid so save_template_attributes doesn't do anything and then
cp_check_const_attributes crashes on the expr_pack_expansion.
Marek
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: C++ PATCH for c++/86063, ICE with attribute with pack expansion
2018-06-14 16:51 ` Marek Polacek
@ 2018-06-14 16:59 ` Jason Merrill
2018-06-14 19:40 ` Marek Polacek
0 siblings, 1 reply; 6+ messages in thread
From: Jason Merrill @ 2018-06-14 16:59 UTC (permalink / raw)
To: Marek Polacek; +Cc: GCC Patches
On Thu, Jun 14, 2018 at 12:51 PM, Marek Polacek <polacek@redhat.com> wrote:
> On Mon, Jun 11, 2018 at 03:00:04PM -0400, Jason Merrill wrote:
>> On Wed, Jun 6, 2018 at 5:18 PM, Marek Polacek <polacek@redhat.com> wrote:
>> > We crash on this testcase containing a bogus attribute, because
>> > cp_check_const_attributes accessed TREE_VALUE of a tree that happened to be
>> > expr_pack_expansion. Since here we're merely trying to evaluate constexpr
>> > arguments, I thought we could skip such bogus arguments.
>>
>> Hmm, attributes should always be a TREE_LIST, lots of places assume
>> that. Why isn't the pack expansion wrapped in a TREE_LIST?
>
> I believe you did that on purpose. There pack comes from
> cp_parser_std_attribute_list. We could wrap it into a TREE_LIST, but then
> tsubst_attribute would have to be tweaked to handle the pack expansion
> correctly.
How so? tsubst_attribute expects to find a pack expansion in the
TREE_VALUE of a TREE_LIST.
And cp_parser_std_attribute_list puts the pack expansion in TREE_VALUE.
Jason
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: C++ PATCH for c++/86063, ICE with attribute with pack expansion
2018-06-14 16:59 ` Jason Merrill
@ 2018-06-14 19:40 ` Marek Polacek
2018-06-14 20:46 ` Jason Merrill
0 siblings, 1 reply; 6+ messages in thread
From: Marek Polacek @ 2018-06-14 19:40 UTC (permalink / raw)
To: Jason Merrill; +Cc: GCC Patches
On Thu, Jun 14, 2018 at 12:59:00PM -0400, Jason Merrill wrote:
> On Thu, Jun 14, 2018 at 12:51 PM, Marek Polacek <polacek@redhat.com> wrote:
> > On Mon, Jun 11, 2018 at 03:00:04PM -0400, Jason Merrill wrote:
> >> On Wed, Jun 6, 2018 at 5:18 PM, Marek Polacek <polacek@redhat.com> wrote:
> >> > We crash on this testcase containing a bogus attribute, because
> >> > cp_check_const_attributes accessed TREE_VALUE of a tree that happened to be
> >> > expr_pack_expansion. Since here we're merely trying to evaluate constexpr
> >> > arguments, I thought we could skip such bogus arguments.
> >>
> >> Hmm, attributes should always be a TREE_LIST, lots of places assume
> >> that. Why isn't the pack expansion wrapped in a TREE_LIST?
> >
> > I believe you did that on purpose. There pack comes from
> > cp_parser_std_attribute_list. We could wrap it into a TREE_LIST, but then
> > tsubst_attribute would have to be tweaked to handle the pack expansion
> > correctly.
>
> How so? tsubst_attribute expects to find a pack expansion in the
> TREE_VALUE of a TREE_LIST.
> And cp_parser_std_attribute_list puts the pack expansion in TREE_VALUE.
Exactly. But what tsubst_attribute gets currently is
<tree_list 0x7ffff001c280 tree_0
purpose <tree_list 0x7ffff0002f00
purpose <identifier_node 0x7fffefec7d80 gnu
normal local bindings <(nil)>>
value <identifier_node 0x7ffff0014f00 aligned
normal local bindings <(nil)>>>
value <expr_pack_expansion 0x7fffefeada20
arg:0 <tree_list 0x7ffff0002f50
value <alignof_expr 0x7ffff0015600 type <integer_type 0x7fffefecd7e0 long unsigned int>
readonly tree_0 arg:0 <template_type_parm 0x7ffff001a1f8 T>
alignas4.C:17:19 start: alignas4.C:17:19 finish: alignas4.C:17:29>>
arg:1 <tree_list 0x7ffff0002f78 value <template_type_parm 0x7ffff001a1f8 T>>>>
so if I were to wrap the expr_pack_expansion in a TREE_LIST, I would have to adjust
tsubst_attribute. But cp_check_const_attributes doesn't expect that the TREE_VALUE
of the above is a non-list. Right?
Marek
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: C++ PATCH for c++/86063, ICE with attribute with pack expansion
2018-06-14 19:40 ` Marek Polacek
@ 2018-06-14 20:46 ` Jason Merrill
0 siblings, 0 replies; 6+ messages in thread
From: Jason Merrill @ 2018-06-14 20:46 UTC (permalink / raw)
To: Marek Polacek; +Cc: GCC Patches
On Thu, Jun 14, 2018 at 3:40 PM, Marek Polacek <polacek@redhat.com> wrote:
> On Thu, Jun 14, 2018 at 12:59:00PM -0400, Jason Merrill wrote:
>> On Thu, Jun 14, 2018 at 12:51 PM, Marek Polacek <polacek@redhat.com> wrote:
>> > On Mon, Jun 11, 2018 at 03:00:04PM -0400, Jason Merrill wrote:
>> >> On Wed, Jun 6, 2018 at 5:18 PM, Marek Polacek <polacek@redhat.com> wrote:
>> >> > We crash on this testcase containing a bogus attribute, because
>> >> > cp_check_const_attributes accessed TREE_VALUE of a tree that happened to be
>> >> > expr_pack_expansion. Since here we're merely trying to evaluate constexpr
>> >> > arguments, I thought we could skip such bogus arguments.
>> >>
>> >> Hmm, attributes should always be a TREE_LIST, lots of places assume
>> >> that. Why isn't the pack expansion wrapped in a TREE_LIST?
>> >
>> > I believe you did that on purpose. There pack comes from
>> > cp_parser_std_attribute_list. We could wrap it into a TREE_LIST, but then
>> > tsubst_attribute would have to be tweaked to handle the pack expansion
>> > correctly.
>>
>> How so? tsubst_attribute expects to find a pack expansion in the
>> TREE_VALUE of a TREE_LIST.
>> And cp_parser_std_attribute_list puts the pack expansion in TREE_VALUE.
>
> Exactly. But what tsubst_attribute gets currently is
>
> <tree_list 0x7ffff001c280 tree_0
> purpose <tree_list 0x7ffff0002f00
> purpose <identifier_node 0x7fffefec7d80 gnu
> normal local bindings <(nil)>>
> value <identifier_node 0x7ffff0014f00 aligned
> normal local bindings <(nil)>>>
> value <expr_pack_expansion 0x7fffefeada20
> arg:0 <tree_list 0x7ffff0002f50
> value <alignof_expr 0x7ffff0015600 type <integer_type 0x7fffefecd7e0 long unsigned int>
> readonly tree_0 arg:0 <template_type_parm 0x7ffff001a1f8 T>
> alignas4.C:17:19 start: alignas4.C:17:19 finish: alignas4.C:17:29>>
> arg:1 <tree_list 0x7ffff0002f78 value <template_type_parm 0x7ffff001a1f8 T>>>>
>
> so if I were to wrap the expr_pack_expansion in a TREE_LIST, I would have to adjust
> tsubst_attribute. But cp_check_const_attributes doesn't expect that the TREE_VALUE
> of the above is a non-list. Right?
Ah, of course, you're already looking at the arguments, I wasn't
reading closely enough. The patch is OK.
Jason
^ permalink raw reply [flat|nested] 6+ messages in thread
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2018-06-06 21:18 C++ PATCH for c++/86063, ICE with attribute with pack expansion Marek Polacek
2018-06-11 19:00 ` Jason Merrill
2018-06-14 16:51 ` Marek Polacek
2018-06-14 16:59 ` Jason Merrill
2018-06-14 19:40 ` Marek Polacek
2018-06-14 20:46 ` Jason Merrill
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