The following program doesn’t compile with NVHPC:
bad.cpp
template <int A> struct S {};
template <int... Ts> void bad() {
using F = void(*)(int);
F data[] = {[](auto) { S<Ts>(); }...};
}
int main(){
bad<1,2,3>();
return 0;
}
> nvc++ -std=c++17 bad.cpp
"bad.cpp", line 4: error: parameter pack "Ts" was referenced but not expanded
F data[] = {[](auto) { S<Ts>(); }...};
^
"bad.cpp", line 4: error: pack expansion does not make use of any argument packs
F data[] = {[](auto) { S<Ts>(); }...};
^
"bad.cpp", line 4: error: expected a "}"
F data[] = {[](auto) { S<Ts>(); }...};
^
detected during instantiation of "void bad<Ts...>() [with Ts=<1, 2, 3>]" at line 8
"bad.cpp", line 4: warning: variable "data" was declared but never referenced
F data[] = {[](auto) { S<Ts>(); }...};
^
detected during instantiation of "void bad<Ts...>() [with Ts=<1, 2, 3>]" at line 8
3 errors detected in the compilation of "bad.cpp".
This compiles without any issues since GCC 8/Clang 6 or newer, Intel ICX 2021.3 also compiled fine.
The error is reproducible on both NVHPC 21.5 and 21.9.
If I swap out the auto in the lambda parameter with the concrete type (int in this case), then it compiles.