Hi,
On 11 Nov 2024, at 20:35, Simon Martin wrote:
> Hi,
>
> On 30 Oct 2024, at 11:46, Simon Martin wrote:
>
>> On 19 Oct 2024, at 11:09, Simon Martin wrote:
>>
>>> We currently ICE in checking mode with cxx_dialect < 17 on the
>>> following
>>> valid code
>>>
>>> === cut here ===
>>> struct X {
>>> X(const X&) {}
>>> };
>>> extern X x;
>>> void foo () {
>>> new X[1]{x};
>>> }
>>> === cut here ===
>>>
>>> The problem is that cp_gimplify_expr gcc_checking_asserts that a
>>> TARGET_EXPR is not TARGET_EXPR_ELIDING_P (or cannot be elided), while
>>> in
>>> this case with cxx_dialect < 17, it is TARGET_EXPR_ELIDING_P but we
>>> have
>>> not even tried to elide.
>>>
>>> This patch relaxes that gcc_checking_assert to not fail when using
>>> cxx_dialect < 17 and -fno-elide-constructors (I considered being more
>>> clever at setting TARGET_EXPR_ELIDING_P appropriately but it looks
>>> more
>>> risky and not worth the extra complexity for a checking assert).
>>>
>>> Successfully tested on x86_64-pc-linux-gnu.
>> Friendly ping. Thanks!
> Friendly ping. Thanks!
Ping. Thanks!
Simon
>>
>>>
>>> PR c++/114619
>>>
>>> gcc/cp/ChangeLog:
>>>
>>> * cp-gimplify.cc (cp_gimplify_expr): Relax gcc_checking_assert
>>> to support the usage of -fno-elide-constructors with c++ < 17.
>>>
>>> gcc/testsuite/ChangeLog:
>>>
>>> * g++.dg/init/no-elide3.C: New test.
>>>
>>> ---
>>> gcc/cp/cp-gimplify.cc | 7 ++++++-
>>> gcc/testsuite/g++.dg/init/no-elide3.C | 11 +++++++++++
>>> 2 files changed, 17 insertions(+), 1 deletion(-)
>>> create mode 100644 gcc/testsuite/g++.dg/init/no-elide3.C
>>>
>>> diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
>>> index 003e68f1ea7..354ea73c63b 100644
>>> --- a/gcc/cp/cp-gimplify.cc
>>> +++ b/gcc/cp/cp-gimplify.cc
>>> @@ -908,7 +908,12 @@ cp_gimplify_expr (tree *expr_p, gimple_seq
>>> *pre_p, gimple_seq *post_p)
>>> gimplify_init_ctor_preeval can materialize subobjects of a
>>> CONSTRUCTOR
>>> on the rhs of an assignment, as in constexpr-aggr1.C. */
>>> gcc_checking_assert (!TARGET_EXPR_ELIDING_P (*expr_p)
>>> - || !TREE_ADDRESSABLE (TREE_TYPE (*expr_p)));
>>> + || !TREE_ADDRESSABLE (TREE_TYPE (*expr_p))
>>> + /* If we explicitly asked not to elide and it's not
>>> + required by the standard, we can't expect elision
>>> + to have happened. */
>>> + || (cxx_dialect < cxx17
>>> + && !flag_elide_constructors));
>>> ret = GS_UNHANDLED;
>>> break;
>>>
>>> diff --git a/gcc/testsuite/g++.dg/init/no-elide3.C
>>> b/gcc/testsuite/g++.dg/init/no-elide3.C
>>> new file mode 100644
>>> index 00000000000..9377d9f0161
>>> --- /dev/null
>>> +++ b/gcc/testsuite/g++.dg/init/no-elide3.C
>>> @@ -0,0 +1,11 @@
>>> +// PR c++/114619
>>> +// { dg-do "compile" { target c++11 } }
>>> +// { dg-options "-fno-elide-constructors" }
>>> +
>>> +struct X {
>>> + X(const X&) {}
>>> +};
>>> +extern X x;
>>> +void foo () {
>>> + new X[1]{x};
>>> +}
>>> --
>>> 2.44.0
