OpenMP fails on iterator and range based loops in Windows debug builds

Mentzer__Stuart — Mon, 06 Jul 2026 11:59:23 GMT

Using recent (2026, 2025, & 2024) oneAPI C++ on Windows I found that OpenMP parallel for on iterator-based and range-based for loops isn't working in debug builds, but index-based loops work. For example, this demo:

#include <vector> #include <iostream> int main() { std::vector< int > v = {0,1,2,3,4,5,6,7,8,9}; // Works // #pragma omp parallel for // for ( std::vector< int >::size_type i = 0; i < v.size(); ++i ) { // ++v[i]; // } // Fails in in debug build at runtime #pragma omp parallel for for ( std::vector< int >::iterator i = v.begin(); i < v.end(); ++i ) { ++(*i); } for ( int i : v ) std::cout << i << std::endl; }

compiled with:
icx /nologo /Qopenmp /Qopenmp-simd- /EHsc /Wall /Od /MDd
builds but terminates at runtime, sometimes popping up a dialog with "ITERATOR LIST CORRUPTED". With /MD or /MT it runs fine.

It doesn't appear to be a VC++ standard library limitation because I see the same problem with my own classes, yet I believe this usage worked some years ago.

Maybe this is a known/documented limitation but I couldn't find any information on it.

sujet OpenMP fails on iterator and range based loops in Windows debug builds dans Intel® oneAPI DPC++/C++ Compiler

OpenMP fails on iterator and range based loops in Windows debug builds