[Flang][OpenMP] Improved reduction clause TODO message

[kiranchandramohan]

Summary

Provide the name of the construct and the clause info (reduction)
in the TODO mesage.

[DavidTruby]

LGTM

flang/lib/Lower/OpenMP.cpp

if (const auto &ifClause =
       untiedAttr = firOpBuilder.getUnitAttr();
     } else if (std::get_if<Fortran::parser::OmpClause::Mergeable>(&clause.u)) {
       mergeableAttr = firOpBuilder.getUnitAttr();
     } else if (const auto &priorityClause =
                    std::get_if<Fortran::parser::OmpClause::Priority>(
                        &clause.u)) {
       priorityClauseOperand = fir::getBase(converter.genExprValue(
           *Fortran::semantics::GetExpr(priorityClause->v), stmtCtx));
+    } else if (std::get_if<Fortran::parser::OmpClause::Reduction>(&clause.u)) {
+      TODO(currentLocation,
+           "Reduction in OpenMP " +
+               llvm::omp::getOpenMPDirectiveName(blockDirective.v) +
+               " construct");
     } else {
-      TODO(currentLocation, "OpenMP Block construct clauses");
+      TODO(converter.getCurrentLocation(), "OpenMP Block construct clause");
     }
   }
 
   for (const auto &clause :
        std::get<Fortran::parser::OmpClauseList>(endBlockDirective.t).v) {
     if (std::get_if<Fortran::parser::OmpClause::Nowait>(&clause.u))
       nowaitAttr = firOpBuilder.getUnitAttr();
   }

flang/test/Lower/OpenMP/Todo/parallel-reduction.f90

 ! RUN: %not_todo_cmd bbc -emit-fir -fopenmp -o - %s 2>&1 | FileCheck %s
 ! RUN: %not_todo_cmd %flang_fc1 -emit-fir -fopenmp -o - %s 2>&1 | FileCheck %s
 
-! CHECK: not yet implemented: OpenMP Block construct clauses
+! CHECK: not yet implemented: Reduction in OpenMP parallel construct
 subroutine reduction_parallel
   integer :: x
   !$omp parallel reduction(+:x)
   x = x + i
   !$omp end parallel
   print *, x
 end subroutine