OK, thanks.
On Wed, Apr 5, 2017 at 5:49 AM, Marek Polacek <pola...@redhat.com> wrote:
> Ping.
>
> On Wed, Mar 29, 2017 at 11:32:39PM +0200, Marek Polacek wrote:
>> On Wed, Mar 29, 2017 at 02:56:51PM -0400, Jason Merrill wrote:
>> > On Wed, Mar 29, 2017 at 12:38 PM, Marek Polacek <pola...@redhat.com> wrote:
>> > > Here we have a reference initialization with NSDMI and *this. We are
>> > > crashing
>> > > because a PLACEHOLDER_EXPR crept into the gimplifier.
>> > >
>> > > This happens since r218653 where set_up_extended_ref_temp was changed to
>> > > use split_nonconstant_init. As a consequence, cp_gimplify_init_expr
>> > > might
>> > > now be receiving
>> > >
>> > > D.2051.p = (void *) &<PLACEHOLDER_EXPR struct A>
>> > >
>> > > instead of
>> > >
>> > > D.2051 = {.p = (void *) &<PLACEHOLDER_EXPR struct A>}
>> > >
>> > > where the RHS was a CONSTRUCTOR. It no longer is, so
>> > > replace_placeholders is
>> > > not called anymore. It occurred to me that we should use the same check
>> > > as in
>> > > store_init_value (i.e. check that the object to be used in the
>> > > substitution is
>> > > a class), but given what split_nonconstant_init might produce, handle
>> > > COMPONENT_REFs specially.
>> > >
>> > > Bootstrapped/regtested on x86_64-linux, ok for trunk and 6?
>> > >
>> > > 2017-03-29 Marek Polacek <pola...@redhat.com>
>> > >
>> > > PR c++/80095 - ICE with this pointer in NSDMI.
>> > > * cp-gimplify.c (cp_gimplify_init_expr): Call
>> > > replace_placeholders
>> > > when TO is a class.
>> > >
>> > > * g++.dg/cpp1y/nsdmi-aggr8.C: New test.
>> > >
>> > > diff --git gcc/cp/cp-gimplify.c gcc/cp/cp-gimplify.c
>> > > index 354ae1a..e530daf 100644
>> > > --- gcc/cp/cp-gimplify.c
>> > > +++ gcc/cp/cp-gimplify.c
>> > > @@ -496,7 +496,16 @@ cp_gimplify_init_expr (tree *expr_p)
>> > > TREE_TYPE (from) = void_type_node;
>> > > }
>> > >
>> > > - if (cxx_dialect >= cxx14 && TREE_CODE (sub) == CONSTRUCTOR)
>> > > + /* split_nonconstant_init might've produced something like
>> > > + D.2051.p = (void *) &<PLACEHOLDER_EXPR struct A>
>> > > + in which case we want to substitute the placeholder with
>> > > + D.2051. */
>> > > + tree op0 = to;
>> > > + while (TREE_CODE (op0) == COMPONENT_REF)
>> > > + op0 = TREE_OPERAND (op0, 0);
>> > > + tree type = TREE_TYPE (op0);
>> > > +
>> > > + if (cxx_dialect >= cxx14 && CLASS_TYPE_P (strip_array_types
>> > > (type)))
>> >
>> > How about doing this checking in replace_placeholders, instead? That
>> > is, if the object isn't a (member of a) class, just return.
>>
>> Sure. I also moved the C++14 check into replace_placeholders, although maybe
>> I shouldn't have.
>>
>> Bootstrapped/regtested on x86_64-linux, ok for trunk and 6?
>>
>> 2017-03-29 Marek Polacek <pola...@redhat.com>
>>
>> PR c++/80095
>> * call.c (build_over_call): Don't check cxx_dialect.
>> * cp-gimplify.c (cp_gimplify_init_expr): Don't check cxx_dialect nor
>> whether SUB is a CONSTRUCTOR.
>> * init.c (build_new_1): Don't check cxx_dialect.
>> * tree.c (replace_placeholders): Add a function comment. Return if
>> not in C++14, or if the object isn't a (member of a) class.
>> * typeck2.c (store_init_value): Don't check cxx_dialect nor whether
>> TYPE is CLASS_TYPE_P.
>>
>> * g++.dg/cpp1y/nsdmi-aggr8.C: New test.
>>
>> diff --git gcc/cp/call.c gcc/cp/call.c
>> index 803fbd4..c15b8e4 100644
>> --- gcc/cp/call.c
>> +++ gcc/cp/call.c
>> @@ -8047,9 +8047,8 @@ build_over_call (struct z_candidate *cand, int flags,
>> tsubst_flags_t complain)
>> {
>> arg = cp_build_indirect_ref (arg, RO_NULL, complain);
>> val = build2 (MODIFY_EXPR, TREE_TYPE (to), to, arg);
>> - if (cxx_dialect >= cxx14)
>> - /* Handle NSDMI that refer to the object being initialized. */
>> - replace_placeholders (arg, to);
>> + /* Handle NSDMI that refer to the object being initialized. */
>> + replace_placeholders (arg, to);
>> }
>> else
>> {
>> diff --git gcc/cp/cp-gimplify.c gcc/cp/cp-gimplify.c
>> index 354ae1a..3f91c35 100644
>> --- gcc/cp/cp-gimplify.c
>> +++ gcc/cp/cp-gimplify.c
>> @@ -496,9 +496,8 @@ cp_gimplify_init_expr (tree *expr_p)
>> TREE_TYPE (from) = void_type_node;
>> }
>>
>> - if (cxx_dialect >= cxx14 && TREE_CODE (sub) == CONSTRUCTOR)
>> - /* Handle aggregate NSDMI. */
>> - replace_placeholders (sub, to);
>> + /* Handle aggregate NSDMI. */
>> + replace_placeholders (sub, to);
>>
>> if (t == sub)
>> break;
>> diff --git gcc/cp/init.c gcc/cp/init.c
>> index 7732795..6a70955 100644
>> --- gcc/cp/init.c
>> +++ gcc/cp/init.c
>> @@ -3373,8 +3373,7 @@ build_new_1 (vec<tree, va_gc> **placement, tree type,
>> tree nelts,
>> object being initialized, replace them now and don't try to
>> preevaluate. */
>> bool had_placeholder = false;
>> - if (cxx_dialect >= cxx14
>> - && !processing_template_decl
>> + if (!processing_template_decl
>> && TREE_CODE (init_expr) == INIT_EXPR)
>> TREE_OPERAND (init_expr, 1)
>> = replace_placeholders (TREE_OPERAND (init_expr, 1),
>> diff --git gcc/cp/tree.c gcc/cp/tree.c
>> index 2757af6..9939135 100644
>> --- gcc/cp/tree.c
>> +++ gcc/cp/tree.c
>> @@ -2813,9 +2813,23 @@ replace_placeholders_r (tree* t, int* walk_subtrees,
>> void* data_)
>> return NULL_TREE;
>> }
>>
>> +/* Replace PLACEHOLDER_EXPRs in EXP with object OBJ. SEEN_P is set if
>> + a PLACEHOLDER_EXPR has been encountered. */
>> +
>> tree
>> replace_placeholders (tree exp, tree obj, bool *seen_p)
>> {
>> + /* This is only relevant for C++14. */
>> + if (cxx_dialect < cxx14)
>> + return exp;
>> +
>> + /* If the object isn't a (member of a) class, do nothing. */
>> + tree op0 = obj;
>> + while (TREE_CODE (op0) == COMPONENT_REF)
>> + op0 = TREE_OPERAND (op0, 0);
>> + if (!CLASS_TYPE_P (strip_array_types (TREE_TYPE (op0))))
>> + return exp;
>> +
>> tree *tp = &exp;
>> replace_placeholders_t data = { obj, false };
>> if (TREE_CODE (exp) == TARGET_EXPR)
>> diff --git gcc/cp/typeck2.c gcc/cp/typeck2.c
>> index 58a01c9..67fbaea 100644
>> --- gcc/cp/typeck2.c
>> +++ gcc/cp/typeck2.c
>> @@ -836,9 +836,8 @@ store_init_value (tree decl, tree init, vec<tree,
>> va_gc>** cleanups, int flags)
>> }
>> value = cp_fully_fold (value);
>>
>> - if (cxx_dialect >= cxx14 && CLASS_TYPE_P (strip_array_types (type)))
>> - /* Handle aggregate NSDMI in non-constant initializers, too. */
>> - value = replace_placeholders (value, decl);
>> + /* Handle aggregate NSDMI in non-constant initializers, too. */
>> + value = replace_placeholders (value, decl);
>>
>> /* DECL may change value; purge caches. */
>> clear_cv_and_fold_caches ();
>> diff --git gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr8.C
>> gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr8.C
>> index e69de29..8c99ffb 100644
>> --- gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr8.C
>> +++ gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr8.C
>> @@ -0,0 +1,16 @@
>> +// PR c++/80095
>> +// { dg-do compile { target c++14 } }
>> +
>> +struct A
>> +{
>> + void* p = this;
>> +};
>> +
>> +void
>> +foo ()
>> +{
>> + const A& a = A{};
>> + A&& a2 = A{};
>> + const A& a3{};
>> + A&& a4{};
>> +}
>>
>> Marek
>
> Marek
