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
