On Thu, May 09, 2024 at 03:47:54PM -0400, Jason Merrill wrote:
> On 5/9/24 12:04, Marek Polacek wrote:
> > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> >
> > -- >8 --
> > Here we crash on a cp_gimplify_expr/TARGET_EXPR assert:
> >
> > /* A TARGET_EXPR that expresses direct-initialization should have
> > been
> > elided by cp_gimplify_init_expr. */
> > gcc_checking_assert (!TARGET_EXPR_DIRECT_INIT_P (*expr_p));
> >
> > the TARGET_EXPR in question is created for the NSDMI in:
> >
> > class Vector { int m_size; };
> > struct S {
> > const Vector &vec{};
> > };
> >
> > where we first need to create a Vector{} temporary, and then bind the
> > vec reference to it. The temporary is represented by a TARGET_EXPR
> > and it cannot be elided. When we create an object of type S, we get
> >
> > D.2848 = {.vec=(const struct Vector &) &TARGET_EXPR <D.2840,
> > {.m_size=0}>}
> >
> > where the TARGET_EXPR is no longer direct-initializing anything.
>
> Seems like the problem is in convert_like_internal:
>
> > bool direct = CONSTRUCTOR_IS_DIRECT_INIT (expr);
> > if (abstract_virtuals_error (NULL_TREE, totype, complain))
> > return error_mark_node;
> > expr = build_value_init (totype, complain);
> > expr = get_target_expr (expr, complain);
> > if (expr != error_mark_node)
> > {
> > TARGET_EXPR_LIST_INIT_P (expr) = true;
> > => TARGET_EXPR_DIRECT_INIT_P (expr) = direct;
> > }
>
> My patch for 50930 assumed that if a CONSTRUCTOR represents syntactic
> direct-initialization, a resulting TARGET_EXPR is itself the direct
> initializer, but that isn't the case here; the temporary is
> copy-initialized.
>
> We could calculate direct-initializanity from cand->flags, but perhaps we
> can just stop trying to set TARGET_EXPR_DIRECT_INIT_P here at all? We don't
> do that for other list-initialization in ck_user, I don't know why I thought
> it was needed for {} specifically. It doesn't seem to be needed for the
> 50930 testcase.
...and it doesn't seem to be needed for any other test. Then not setting
the flag in the first place is better than resetting it later, sure.
I thought about leaving a gcc_checking_assert (!TARGET_EXPR_DIRECT_INIT_P)
in cp_build_addr_expr_1, but since we already have that assert when
gimplifying, I dropped it.
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk/branches?
-- >8 --
Here we crash on a cp_gimplify_expr/TARGET_EXPR assert:
/* A TARGET_EXPR that expresses direct-initialization should have been
elided by cp_gimplify_init_expr. */
gcc_checking_assert (!TARGET_EXPR_DIRECT_INIT_P (*expr_p));
the TARGET_EXPR in question is created for the NSDMI in:
class Vector { int m_size; };
struct S {
const Vector &vec{};
};
where we first need to create a Vector{} temporary, and then bind the
vec reference to it. The temporary is represented by a TARGET_EXPR
and it cannot be elided. When we create an object of type S, we get
D.2848 = {.vec=(const struct Vector &) &TARGET_EXPR <D.2840, {.m_size=0}>}
where the TARGET_EXPR is no longer direct-initializing anything.
Fixed by not setting TARGET_EXPR_DIRECT_INIT_P in convert_like_internal/ck_user.
PR c++/114854
gcc/cp/ChangeLog:
* call.cc (convert_like_internal) <case ck_user>: Don't set
TARGET_EXPR_DIRECT_INIT_P.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1y/nsdmi-aggr22.C: New test.
---
gcc/cp/call.cc | 6 +-----
gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr22.C | 12 ++++++++++++
2 files changed, 13 insertions(+), 5 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr22.C
diff --git a/gcc/cp/call.cc b/gcc/cp/call.cc
index e058da7735f..ed68eb3c568 100644
--- a/gcc/cp/call.cc
+++ b/gcc/cp/call.cc
@@ -8597,16 +8597,12 @@ convert_like_internal (conversion *convs, tree expr,
tree fn, int argnum,
&& TYPE_HAS_DEFAULT_CONSTRUCTOR (totype)
&& !processing_template_decl)
{
- bool direct = CONSTRUCTOR_IS_DIRECT_INIT (expr);
if (abstract_virtuals_error (NULL_TREE, totype, complain))
return error_mark_node;
expr = build_value_init (totype, complain);
expr = get_target_expr (expr, complain);
if (expr != error_mark_node)
- {
- TARGET_EXPR_LIST_INIT_P (expr) = true;
- TARGET_EXPR_DIRECT_INIT_P (expr) = direct;
- }
+ TARGET_EXPR_LIST_INIT_P (expr) = true;
return expr;
}
diff --git a/gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr22.C
b/gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr22.C
new file mode 100644
index 00000000000..a4f9ae19ca9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr22.C
@@ -0,0 +1,12 @@
+// PR c++/114854
+// { dg-do compile { target c++14 } }
+
+struct Vector {
+ int m_size;
+};
+struct S {
+ const Vector &vec{};
+};
+
+void spawn(S);
+void test() { spawn({}); }
base-commit: 0a99ad5c52caa06c113b1889bbe6634812b89be5
--
2.45.0
