v1: two host variables sharing a local name with different standard names will compile but clobber silently

[jimmielin]

Description

This is from Claude when investigating whether #772 applies to capgen-v1.

When looking at host vars imported by use ... only:, Claude found that two host variables sharing a local name with different standard names

v1 accepts this silently (exit 0, no warning) and emits a cap where the control-arg dummy shadows the use-associated host variable:

use test_host_mod, only: ncols, nthreads   ! host var, std name test_host_thread_count
...
  subroutine grp_one_run(..., nthreads, ...)
    integer, intent(in) :: nthreads         ! control arg, std name number_of_threads
    ...
    call thr_use_run(ncol=..., ni=nthreads, ...)   ! binds to the DUMMY

The scheme asked for test_host_thread_count but receives the framework's thread count. It compiles clean and runs with wrong data. I confirmed the Fortran semantics with a standalone test (dummy value 7 wins over host parameter 999), so this is a silent wrong-value bug, not a compile error.

Steps to Reproduce

commit ed284a8a4a6507f8c684839dbe2a2e2770b3a09d (HEAD, upstream/feature/capgen-v1)

see above.

Additional Context

Output

[climbfuji]

Thanks for the check. I assigned this to myself, will work on it after my PTO