c++: Skip unnamed bit-fields more
Commit Message
As Jason noticed in
<https://gcc.gnu.org/pipermail/gcc-patches/2021-November/583592.html>,
we shouldn't require an initializer for an unnamed bit-field, because,
as [class.bit] says, they cannot be initialized.
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
gcc/cp/ChangeLog:
* class.c (default_init_uninitialized_part): Use
next_initializable_field.
* method.c (walk_field_subobs): Skip unnamed bit-fields.
gcc/testsuite/ChangeLog:
* g++.dg/init/bitfield6.C: New test.
---
gcc/cp/class.c | 7 +++----
gcc/cp/method.c | 4 +++-
gcc/testsuite/g++.dg/init/bitfield6.C | 20 ++++++++++++++++++++
3 files changed, 26 insertions(+), 5 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/init/bitfield6.C
base-commit: d626fe77cdc40de0ae1651c8b94090eea73a719f
Comments
On 11/8/21 14:49, Marek Polacek wrote:
> As Jason noticed in
> <https://gcc.gnu.org/pipermail/gcc-patches/2021-November/583592.html>,
> we shouldn't require an initializer for an unnamed bit-field, because,
> as [class.bit] says, they cannot be initialized.
>
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
OK.
> gcc/cp/ChangeLog:
>
> * class.c (default_init_uninitialized_part): Use
> next_initializable_field.
> * method.c (walk_field_subobs): Skip unnamed bit-fields.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/init/bitfield6.C: New test.
> ---
> gcc/cp/class.c | 7 +++----
> gcc/cp/method.c | 4 +++-
> gcc/testsuite/g++.dg/init/bitfield6.C | 20 ++++++++++++++++++++
> 3 files changed, 26 insertions(+), 5 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/init/bitfield6.C
>
> diff --git a/gcc/cp/class.c b/gcc/cp/class.c
> index f16e50b9de9..bf92300a178 100644
> --- a/gcc/cp/class.c
> +++ b/gcc/cp/class.c
> @@ -5455,10 +5455,9 @@ default_init_uninitialized_part (tree type)
> if (r)
> return r;
> }
> - for (t = TYPE_FIELDS (type); t; t = DECL_CHAIN (t))
> - if (TREE_CODE (t) == FIELD_DECL
> - && !DECL_ARTIFICIAL (t)
> - && !DECL_INITIAL (t))
> + for (t = next_initializable_field (TYPE_FIELDS (type)); t;
> + t = next_initializable_field (DECL_CHAIN (t)))
> + if (!DECL_INITIAL (t) && !DECL_ARTIFICIAL (t))
> {
> r = default_init_uninitialized_part (TREE_TYPE (t));
> if (r)
> diff --git a/gcc/cp/method.c b/gcc/cp/method.c
> index 1023aefc575..935946f5eef 100644
> --- a/gcc/cp/method.c
> +++ b/gcc/cp/method.c
> @@ -2295,7 +2295,9 @@ walk_field_subobs (tree fields, special_function_kind sfk, tree fnname,
> {
> tree mem_type, argtype, rval;
>
> - if (TREE_CODE (field) != FIELD_DECL || DECL_ARTIFICIAL (field))
> + if (TREE_CODE (field) != FIELD_DECL
> + || DECL_ARTIFICIAL (field)
> + || DECL_UNNAMED_BIT_FIELD (field))
> continue;
>
> /* Variant members only affect deletedness. In particular, they don't
> diff --git a/gcc/testsuite/g++.dg/init/bitfield6.C b/gcc/testsuite/g++.dg/init/bitfield6.C
> new file mode 100644
> index 00000000000..70854ee9588
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/init/bitfield6.C
> @@ -0,0 +1,20 @@
> +// { dg-do compile { target c++11 } }
> +
> +struct A
> +{
> + int : 8;
> + int i = 42;
> +};
> +
> +constexpr A a;
> +
> +struct B : A {
> +};
> +
> +constexpr B b;
> +
> +struct C {
> + int : 0;
> +};
> +
> +constexpr C c;
>
> base-commit: d626fe77cdc40de0ae1651c8b94090eea73a719f
>
@@ -5455,10 +5455,9 @@ default_init_uninitialized_part (tree type)
if (r)
return r;
}
- for (t = TYPE_FIELDS (type); t; t = DECL_CHAIN (t))
- if (TREE_CODE (t) == FIELD_DECL
- && !DECL_ARTIFICIAL (t)
- && !DECL_INITIAL (t))
+ for (t = next_initializable_field (TYPE_FIELDS (type)); t;
+ t = next_initializable_field (DECL_CHAIN (t)))
+ if (!DECL_INITIAL (t) && !DECL_ARTIFICIAL (t))
{
r = default_init_uninitialized_part (TREE_TYPE (t));
if (r)
@@ -2295,7 +2295,9 @@ walk_field_subobs (tree fields, special_function_kind sfk, tree fnname,
{
tree mem_type, argtype, rval;
- if (TREE_CODE (field) != FIELD_DECL || DECL_ARTIFICIAL (field))
+ if (TREE_CODE (field) != FIELD_DECL
+ || DECL_ARTIFICIAL (field)
+ || DECL_UNNAMED_BIT_FIELD (field))
continue;
/* Variant members only affect deletedness. In particular, they don't
new file mode 100644
@@ -0,0 +1,20 @@
+// { dg-do compile { target c++11 } }
+
+struct A
+{
+ int : 8;
+ int i = 42;
+};
+
+constexpr A a;
+
+struct B : A {
+};
+
+constexpr B b;
+
+struct C {
+ int : 0;
+};
+
+constexpr C c;