It seems to me that clang has some problems when using omp collapse in template function.
I've attached a minimal example. Clang (9, 10, 11) can't compile it, while gcc compiles it just fine. Is this a compiler error or is my code doing something illegal? Making this function non template or dropping the collapse clause makes it compile just fine.
#include <vector>
#include <iostream>
template <typename T>
void test(const std::vector<int> begin_vec) {
#pragma omp parallel for collapse(2)
for (int n = begin_vec.at(0); n < 0; n++) {
for (int h = begin_vec.at(1); h < 1; h++) {
for (int w = begin_vec.at(2); w < 2; w++) {
std::cout << n + h + w << std::endl;
}}}
}
int main() {
test<int>({0,0,0});
}
To compile clang++-10 -fopenmp test.cpp
For me, clang produces the following error
test.cpp:9:16: error: 'this' argument to member function 'at' has type 'const std::vector<int>', but function is not marked const
for (int h = begin_vec.at(1); h < 1; h++) {
^~~~~~~~~
test.cpp:16:3: note: in instantiation of function template specialization 'test<int>' requested here
test<int>({0,0,0});
^
/usr/bin/../lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/bits/stl_vector.h:1092:7: note: 'at' declared here
at(size_type __n)
^
(I've also tried to use libc++, but it didn't change anything)
