CODEWITHSUNDEEP
c++c++17openmpclang++
eudoxos
eudoxos

Reputation: 19075

clang 10 & OpenMP on range-based for error (docs say should be ok)

I am testing clang 10.0 on an c++17 & OpenMP project and get errors when #pragma omp parallel for is used on range-based for.

Release notes for clang 10, in the OpenMP Support in Clang section, say quite clearly:

When I compile a MWE with clang++-10 -fopenmp -std=c++17 (see https://godbolt.org/z/fdTeMo for online compiler):

#include<vector>
#include<iostream>
int main(int argc, char** argv){
    std::vector<int> ii{0,11,22,33,44,55,66};
    #pragma omp parallel for
    for(int& i: ii){
        std::cerr<<i<<std::endl;
    }
}

I get:

<source>:6:5: error: statement after '#pragma omp parallel for' must be a for loop

    for(int& i: ii){

    ^

1 error generated.

Compiler returned: 1

What's up?

Upvotes: 1

Views: 622

Answers (1)

dfrib
dfrib

Reputation: 73196

Support for range-based for loops was added to OpenMP 5.0, and, as is also described in the Clang 10 Release Notes that you link to, you need to explicitly use the -fopenmp-version=50 option to activate support for it:

OpenMP Support in Clang

Use -fopenmp-version=50 option to activate support for OpenMP 5.0.

Thus, if we expand you compilation command to clang++-10 -fopenmp -fopenmp-version=50 -std=c++17, the OMP pragma accepts the range based for loop that follows it.

DEMO.

Upvotes: 4

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