[Bug c++/103885] New: ICE in capturing lambda for certain constexpr/auto combination

[cbcode at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103885

Bug ID: 103885
   Summary: ICE in capturing lambda for certain constexpr/auto
combination
   Product: gcc
   Version: 11.2.0
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: c++
  Assignee: unassigned at gcc dot gnu.org
  Reporter: cbcode at gmail dot com
  Target Milestone: ---

ICE on the line indicated below.

void test() {
constexpr int N = 1;
constexpr auto a1 = [](auto){
static_assert(N == 1); //OK
return 2;
}(3);
constexpr auto a2 = [=](auto){
static_assert(N == 1); //OK
return 2;
}(3);
constexpr auto a3 = [&](int){
static_assert(N == 1); //OK
return 2;
}(3);
constexpr auto a4 = [&](auto){
static_assert(N == 1); //ICE in tsubst_copy, at cp/pt.c:16780
return 2;
}(3);
}

[Bug c++/103943] New: ICE building qualified name inside class with variadic CTAD

[cbcode at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103943

Bug ID: 103943
   Summary: ICE building qualified name inside class with variadic
CTAD
   Product: gcc
   Version: 11.2.0
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: c++
  Assignee: unassigned at gcc dot gnu.org
  Reporter: cbcode at gmail dot com
  Target Milestone: ---

// gcc has known problems with variadic CTAD, not sure if this is related.
// regression (was fine in v8.3.0).

template struct F0 { //OK
R(*fun_ptr)(AA...);
};
template struct F1 { //OK
R(*fun_ptr)(AA...);
F1(R(*fun_ptr)(AA...)) : fun_ptr(fun_ptr) {}
};
template struct F2 { //OK
R(*fun_ptr)(AA...);
using fun_ptr_t = decltype(fun_ptr);
F2(fun_ptr_t fun_ptr) : fun_ptr(fun_ptr) {}
};
template struct F3 {
R(*fun_ptr)(AA...);
//  using fun_ptr_t = decltype(fun_ptr); //OK as in F2
using fun_ptr_t = decltype(F3::fun_ptr); //ICE: Segmentation fault
//  using fun_ptr_t = decltype(F3::fun_ptr); //ICE: Segmentation
fault
F3(fun_ptr_t fun_ptr) : fun_ptr(fun_ptr) {}
};
template struct F4 {
static R fun_not_implemented(AA...);
//  using fun_ptr_t = decltype(&fun_not_implemented); //OK
using fun_ptr_t = decltype(&F4::fun_not_implemented); //OK with aggregate
initialization (no ctor)
//  using fun_ptr_t = decltype(&F4::fun_not_implemented); //OK with
aggregate initialization (no ctor)
fun_ptr_t fun_ptr;
};
template struct F5 { //OK
static R fun_not_implemented(AA...);
using fun_ptr_t = decltype(&fun_not_implemented);
fun_ptr_t fun_ptr;
F5(fun_ptr_t fun_ptr) : fun_ptr(fun_ptr) {}
};
template struct F6 {
static R fun_not_implemented(AA...);
//  using fun_ptr_t = decltype(&fun_not_implemented); //OK as in F5
using fun_ptr_t = decltype(&F6::fun_not_implemented); //ICE: in
build_qualified_name, at cp/tree.c:2238
//  using fun_ptr_t = decltype(&F6::fun_not_implemented); //ICE: in
build_qualified_name, at cp/tree.c:2238
fun_ptr_t fun_ptr;
F6(fun_ptr_t fun_ptr) : fun_ptr(fun_ptr) {}
};
template F0(R(*fun_ptr)(AA...)) -> F0;
template F1(R(*fun_ptr)(AA...)) -> F1;
template F2(R(*fun_ptr)(AA...)) -> F2;
template F3(R(*fun_ptr)(AA...)) -> F3;
template F4(R(*fun_ptr)(AA...)) -> F4;
template F5(R(*fun_ptr)(AA...)) -> F5;
template F6(R(*fun_ptr)(AA...)) -> F6;

int fun(int a) {
return a + 1;
}
#pragma GCC diagnostic ignored "-Wunused-but-set-variable"
void test() {
auto f0 = F0{&fun}; //OK
auto f1 = F1{&fun}; //OK
auto f2 = F2{&fun}; //OK
auto f3 = F3{&fun}; //ICE: Segmentation fault
auto f4 = F4{&fun}; //OK
auto f5 = F5{&fun}; //OK
auto f6 = F6{&fun}; //ICE: in build_qualified_name, at cp/tree.c:2238
}