[PATCH] c++: zero_init_expr_p of dependent expression

[Jason Merrill]

On 6/16/20 9:06 AM, Patrick Palka wrote:
> On Thu, Apr 23, 2020 at 5:17 PM Jason Merrill <jason@redhat.com> wrote:
>>
>> On 4/23/20 4:09 PM, Patrick Palka wrote:
>>> This fixes a ICE coming from mangle.c:write_expression when compiling the
>>> ranges-v3 testsuite; the added testcase is a reduced reproducer of the ICE.
>>>
>>> Bootstrapped and regtested on x86_64-pc-linux-gnu, and also tested on the
>>> cmcstl2, fmt and range-v3 libraries.  Does this look OK to commit?
>>
>> OK.
> 
> Is it OK to backport the same patch to the 9 branch in order to resolve PR95678?

OK.

>>
>>> gcc/cp/ChangeLog:> >
>>>        * tree.c (zero_init_expr_p): Use uses_template_parms instead of
>>>        dependent_type_p.
>>>
>>> gcc/testsuite/ChangeLog:
>>>
>>>        * g++.dg/cpp0x/dependent3.C: New test.
>>> ---
>>>    gcc/cp/tree.c                           |  2 +-
>>>    gcc/testsuite/g++.dg/cpp0x/dependent3.C | 28 +++++++++++++++++++++++++
>>>    2 files changed, 29 insertions(+), 1 deletion(-)
>>>    create mode 100644 gcc/testsuite/g++.dg/cpp0x/dependent3.C
>>>
>>> diff --git a/gcc/cp/tree.c b/gcc/cp/tree.c
>>> index 090c565c093..8840932dba2 100644
>>> --- a/gcc/cp/tree.c
>>> +++ b/gcc/cp/tree.c
>>> @@ -4486,7 +4486,7 @@ bool
>>>    zero_init_expr_p (tree t)
>>>    {
>>>      tree type = TREE_TYPE (t);
>>> -  if (!type || dependent_type_p (type))
>>> +  if (!type || uses_template_parms (type))
>>>        return false;
>>>      if (zero_init_p (type))
>>>        return initializer_zerop (t);
>>> diff --git a/gcc/testsuite/g++.dg/cpp0x/dependent3.C b/gcc/testsuite/g++.dg/cpp0x/dependent3.C
>>> new file mode 100644
>>> index 00000000000..caf7e1cd4a4
>>> --- /dev/null
>>> +++ b/gcc/testsuite/g++.dg/cpp0x/dependent3.C
>>> @@ -0,0 +1,28 @@
>>> +// { dg-do compile { target c++11 } }
>>> +
>>> +template<typename c>
>>> +struct d
>>> +{
>>> +  using e = c;
>>> +};
>>> +
>>> +template<class f>
>>> +struct g
>>> +{
>>> +  using h = typename d<f>::e;
>>> +
>>> +  template<class i, class j>
>>> +  auto operator()(i, j k) -> decltype(h{k});
>>> +};
>>> +
>>> +template<class l>
>>> +void m()
>>> +{
>>> +  int a[1];
>>> +  l{}(a, a);
>>> +}
>>> +
>>> +int main()
>>> +{
>>> +  m<g<int *>>();
>>> +}
>>>
>>
>