Bug when using OpenMP line continuation with conditional compilation sections

[jjesse]

I've been encountering a bug that causes a compiler error when using line continuation for OpenMP directives that are nested inside of !dec$ style conditional compilation sections. I'm seeing it when using ifx 2025.1, but the issue seems to have popped up in both ifort and ifx sometime during oneAPI 2024. A minimal reproducible example along with a CMake build script has been attached.

Although !dec$ sections are failing, using C-style #ifdefs appears to be okay.

The line continuation seems to cause the compiler to lose track of the conditional so that the compiler reports that it is not closed at the end:

XXXX/main-dec.f90(34): warning #5273: Directive found when statement continuation expected. Directive ignored.
!$omp partial_sum) shared(total_sum)
-----^
XXXX/main-dec.f90(35): warning #5273: Directive found when statement continuation expected. Directive ignored.
!dec$ endif
-----^
XXXX/main-dec.f90(58): error #5174: Unterminated conditional compilation directive
end program
-----------^