The symbol DP is imported in two USE statements, which is not allowed
because it is ambiguous, and so the compiler uses neither - which
causes later errors.  Not all compilers will do the same following
the first error (double import), and so later messages will vary.

NAG Fortran Compiler Release 5.2(668)
Error: ex_08.4.5.f90, line 5: Symbol DP found both in module DOUBLE and in LAPACK
       detected at =@DP
Error: ex_08.4.5.f90, line 5: Implicit type for DP
       detected at DP@)
Error: ex_08.4.5.f90, line 5: DP is not a constant
       detected at _@DP
Warning: ex_08.4.5.f90, line 21: Symbol DP referenced but never set
         detected at MAIN@<end-of-statement>
[NAG Fortran Compiler pass 1 error termination, 3 errors, 1 warning]