Hi,
On 11 Dec 2024, at 22:27, Simon Martin wrote:
> Hi,
>
> On 29 Nov 2024, at 15:33, Simon Martin wrote:
>
>> We currently ICE upon the following code, that is valid under
>> -Wno-pointer-arith:
>>
>> === cut here ===
>> int main() {
>> decltype( [](auto) { return sizeof(void); } ) x;
>> return x.operator()(0);
>> }
>> === cut here ===
>>
>> The problem is that "fold_sizeof_expr (sizeof(void))" returns
>> size_one_node, that has a different TREE_TYPE from that of the sizeof
>> expression, which later triggers an assert in
>> cxx_eval_store_expression.
>>
>> This patch makes sure that fold_sizeof_expr always returns a tree with
>> the type requested.
>>
>> Successfully tested on x86_64-pc-linux-gnu.
> Ping.
Ping. Thanks!
Simon
>>
>> PR c++/117775
>>
>> gcc/cp/ChangeLog:
>>
>> * decl.cc (fold_sizeof_expr): Make sure the folded result has
>> the requested TREE_TYPE.
>>
>> gcc/testsuite/ChangeLog:
>>
>> * g++.dg/cpp2a/constexpr-117775.C: New test.
>>
>> ---
>> gcc/cp/decl.cc | 1 +
>> gcc/testsuite/g++.dg/cpp2a/constexpr-117775.C | 13 +++++++++++++
>> 2 files changed, 14 insertions(+)
>> create mode 100644 gcc/testsuite/g++.dg/cpp2a/constexpr-117775.C
>>
>> diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
>> index 80485f0a428..fbe1407a2d2 100644
>> --- a/gcc/cp/decl.cc
>> +++ b/gcc/cp/decl.cc
>> @@ -11686,6 +11686,7 @@ fold_sizeof_expr (tree t)
>> false, false);
>> if (r == error_mark_node)
>> r = size_one_node;
>> + r = cp_fold_convert (TREE_TYPE (t), r);
>> return r;
>> }
>>
>> diff --git a/gcc/testsuite/g++.dg/cpp2a/constexpr-117775.C
>> b/gcc/testsuite/g++.dg/cpp2a/constexpr-117775.C
>> new file mode 100644
>> index 00000000000..59fc0d332b9
>> --- /dev/null
>> +++ b/gcc/testsuite/g++.dg/cpp2a/constexpr-117775.C
>> @@ -0,0 +1,13 @@
>> +// PR c++/117775
>> +// Check that we don't ICE and have sizeof(void)==1 under
>> -Wno-pointer-arith
>> +// { dg-do run { target c++20 } }
>> +// { dg-additional-options "-Wno-pointer-arith" }
>> +
>> +int main() {
>> + struct why :
>> + decltype( [](auto) {
>> + return sizeof(void);
>> + })
>> + {} x;
>> + return 1 - x.operator()(0);
>> +}
>> --
>> 2.44.0
