How to test for errors without line?

[Thomas Koenig via Gcc]

Hi,

I want to add a test test case for an error I want to emit for an
option for an ilp32 system.  My current attempt is

! { dg-do compile }
! { dg-options "-ffrontend-optimize -fexternal-blas64" }
! { dg-require-effective-target ilp32 }
! { dg-excess-errors "-ffrontend-optimize required for -fexternal-blas64" }
! PR 121161 - do not use -fexternal-blas64 with a 32-bit system.
subroutine foo(a,b,c,n)
  implicit none
  integer(kind=8) :: n
  real, dimension(n,n) :: a, b, c
  c = matmul(a,b)
end subroutine foo

This gives the unexpected (for me) output in the log file

XFAIL: gfortran.dg/matmul_blas_4.f90   -O  (test for excess errors)
Excess errors:
f951: Fatal Error: -fexternal-blas64 requires a 64-bit system
compilation terminated.

and finally

                === gfortran Summary ===

# of expected failures          1

I can live with that, but it seems a little strange - is there a
way to check for an error message that is not associated with
a particular line number?

Best regards

        Thomas