Ping. Though I reckon it may be better to defer this to 15.
On Fri, Mar 01, 2024 at 07:58:51PM -0500, Marek Polacek wrote:
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk? I don't
> claim that this has to go to 14 though.
>
> -- >8 --
> ...from another array in a mem-initializer should not be accepted.
>
> We already reject
>
> struct string {} a[1];
> string x[1](a);
>
> but
>
> struct pair {
> string s[1];
> pair() : s(a) {}
> };
>
> is wrongly accepted.
>
> It started to be accepted with r0-110915-ga034826198b771:
> <https://gcc.gnu.org/pipermail/gcc-patches/2011-August/320236.html>
> which was supposed to be a cleanup, not a deliberate change to start
> accepting the code. The build_vec_init_expr code was added in r165976:
> <https://gcc.gnu.org/pipermail/gcc-patches/2010-October/297582.html>.
>
> It appears that we do the magic copy array when we have a defaulted
> constructor and we generate code for its mem-initializer which
> initializes an array. I also see that we go that path for compound
> literals. So when initializing an array member, we can limit building
> up a VEC_INIT_EXPR to those special cases.
>
> PR c++/59465
>
> gcc/cp/ChangeLog:
>
> * init.cc (can_init_array_with_p): New.
> (perform_member_init): Check it.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/init/array62.C: New test.
> * g++.dg/init/array63.C: New test.
> * g++.dg/init/array64.C: New test.
> ---
> gcc/cp/init.cc | 27 ++++++++++++++++++++++++++-
> gcc/testsuite/g++.dg/init/array62.C | 19 +++++++++++++++++++
> gcc/testsuite/g++.dg/init/array63.C | 13 +++++++++++++
> gcc/testsuite/g++.dg/init/array64.C | 22 ++++++++++++++++++++++
> 4 files changed, 80 insertions(+), 1 deletion(-)
> create mode 100644 gcc/testsuite/g++.dg/init/array62.C
> create mode 100644 gcc/testsuite/g++.dg/init/array63.C
> create mode 100644 gcc/testsuite/g++.dg/init/array64.C
>
> diff --git a/gcc/cp/init.cc b/gcc/cp/init.cc
> index d2586fad86b..fb8c0e521fb 100644
> --- a/gcc/cp/init.cc
> +++ b/gcc/cp/init.cc
> @@ -934,6 +934,31 @@ find_uninit_fields (tree *t, hash_set<tree>
> *uninitialized, tree member)
> }
> }
>
> +/* Return true if it's OK to initialize an array from INIT. Mere mortals
> + can't copy arrays, but the compiler can do so with a VEC_INIT_EXPR in
> + certain cases. */
> +
> +static bool
> +can_init_array_with_p (tree init)
> +{
> + if (!init)
> + return true;
> +
> + /* We're called from synthesize_method, and we're processing the
> + mem-initializers of a constructor. */
> + if (DECL_DEFAULTED_FN (current_function_decl))
> + return true;
> + /* As an extension, we allow copying from a compound literal. */
> + else if (TREE_CODE (init) == TARGET_EXPR)
> + {
> + init = TARGET_EXPR_INITIAL (init);
> + if (TREE_CODE (init) == CONSTRUCTOR)
> + return CONSTRUCTOR_C99_COMPOUND_LITERAL (init);
> + }
> +
> + return false;
> +}
> +
> /* Initialize MEMBER, a FIELD_DECL, with INIT, a TREE_LIST of
> arguments. If TREE_LIST is void_type_node, an empty initializer
> list was given; if NULL_TREE no initializer was given. UNINITIALIZED
> @@ -1085,7 +1110,7 @@ perform_member_init (tree member, tree init,
> hash_set<tree> &uninitialized)
> else if (type_build_ctor_call (type)
> || (init && CLASS_TYPE_P (strip_array_types (type))))
> {
> - if (TREE_CODE (type) == ARRAY_TYPE)
> + if (TREE_CODE (type) == ARRAY_TYPE && can_init_array_with_p (init))
> {
> if (init == NULL_TREE
> || same_type_ignoring_top_level_qualifiers_p (type,
> diff --git a/gcc/testsuite/g++.dg/init/array62.C
> b/gcc/testsuite/g++.dg/init/array62.C
> new file mode 100644
> index 00000000000..6d3935d7a66
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/init/array62.C
> @@ -0,0 +1,19 @@
> +// PR c++/59465
> +// { dg-do compile }
> +
> +struct string {} a[1];
> +struct pair {
> + string s[1];
> + pair() : s(a) {} // { dg-error "array must be initialized" }
> +};
> +
> +struct S {
> + char s[10];
> + S() : s("aaa") {}
> +};
> +
> +void
> +g ()
> +{
> + string x[1](a); // { dg-error "array must be initialized" }
> +}
> diff --git a/gcc/testsuite/g++.dg/init/array63.C
> b/gcc/testsuite/g++.dg/init/array63.C
> new file mode 100644
> index 00000000000..96bc9a64b26
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/init/array63.C
> @@ -0,0 +1,13 @@
> +// PR c++/59465
> +// { dg-do compile }
> +
> +struct I {
> + const bool b;
> +};
> +struct O {
> + I a[2];
> + static I const data[2];
> + O() : a(data){} // { dg-error "array must be initialized" }
> +};
> +
> +I const O::data[2] = {true, false};
> diff --git a/gcc/testsuite/g++.dg/init/array64.C
> b/gcc/testsuite/g++.dg/init/array64.C
> new file mode 100644
> index 00000000000..bbdd70c6df8
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/init/array64.C
> @@ -0,0 +1,22 @@
> +// PR c++/59465
> +// { dg-do compile }
> +
> +static const int my_size = 10;
> +
> +class UserType
> +{
> +public:
> + UserType(): f_(){}
> +private:
> +int f_;
> +};
> +
> +typedef UserType Array[my_size];
> +
> +class Foo
> +{
> +public:
> + Foo(Array& m) : m_(m) {}; // { dg-error "array must be initialized" }
> +private:
> + Array m_;
> +};
>
> base-commit: 574fd1f17f100c7c355ad26bc525ab5a3386bb2d
> --
> 2.44.0
>
Marek
