Task and taskloop array-element reductions can introduce both a
reduction block argument and an implicit firstprivate block argument for
the base array. Sequential symbol binding can then select the wrong
argument for references in the construct body.
Reject these cases until lowering can distinguish the reduction element
from other uses of the base array. Keep supported array-element reduction
coverage in the existing test and move the unsupported task forms to
focused TODO tests.
Assisted-by: Codex
Tom Eccles
75415b1b18