[flang] [llvm] [Frontend][OpenMP] Reduction modifier must be applied somewhere (PR #92160)

[Krzysztof Parzyszek via llvm-commits]

kparzysz wrote:

> @kparzysz, I'm still getting an assertion in Decomposer.cpp with my internal test even with this latest change. Are you still working on this, or should I work to create a small reproducer?

This test uses an invalid reduction modifier for this construct.  Before this fix we just silently dropped the modifier, now we will assert.  I will open a follow-up issue to have this detected in the semantic checks and emit a user-friendly error.

Does your code have this specific combination of reduction/construct?  IIRC, it asserted before any of the follow up fixes, so it's likely a different problem.  Please do create a testcase for it.

https://github.com/llvm/llvm-project/pull/92160