Compiler error C7688

'pragma omp atomic': expected an expression of scalar type

Remarks

OpenMP restricts expressions in #pragma omp atomic constructs to scalar type.

Compiler error C7688 is new in Visual Studio 2022 version 17.4. In previous compiler versions, the compiler would emit error C3048.

Example

The sample code shows diagnostics generated for non-scalar types in #pragma omp atomic constructs.

// C7688.cpp
// compile using /c /openmp:llvm
struct S { char c; };
S operator+(S, int);

void test()
{
    S s1, s2;
    #pragma omp atomic capture
    { s1 = s2; s2 = s1 + 1; }
}
/*
When built, the compiler emits:

.\C7688.cpp(10,10): error C7688: '#pragma omp atomic': expected an expression of scalar type
    { s1 = s2; s2 = s1 + 1; }
         ^
.\C7688.cpp(10,10): note: type is 'S'
*/

To resolve this issue, use scalar types in #pragma omp atomic constructs.