It turned out that a compiler built without offloading support
and one with can produce slightly different diagnostic.
Offloading support implies ENABLE_OFFLOAD which implies that
g->have_offload is set when offloading is actually needed.
In cgraphunit.c, the latter causes flag_generate_offload = 1,
which in turn affects tree.c's free_lang_data.
The result is that the front-end specific diagnostic gets reset
('tree_diagnostics_defaults (global_dc)'), which affects in this
case 'Warning' vs. 'warning' via the Fortran frontend.
Result: 'Warning:' vs. 'warning:'.
Side note: Other FE also override the diagnostic, leading to
similar differences, e.g. the C++ FE outputs mangled function
names differently, cf. patch thread.
libgomp/ChangeLog:
* testsuite/libgomp.oacc-fortran/par-reduction-2-1.f:
Use [Ww]arning in dg-bogus as FE diagnostic and default
diagnostic differ and the result depends on ENABLE_OFFLOAD.
* testsuite/libgomp.oacc-fortran/par-reduction-2-2.f: Likewise.
* testsuite/libgomp.oacc-fortran/parallel-dims.f90: Likewise.
* testsuite/libgomp.oacc-fortran/parallel-reduction.f90: Likewise.
gcc/testsuite/ChangeLog:
* gfortran.dg/goacc/classify-serial.f95:
Use [Ww]arning in dg-bogus as FE diagnostic and default
diagnostic differ and the result depends on ENABLE_OFFLOAD.
* gfortran.dg/goacc/kernels-decompose-2.f95: Likewise.
* gfortran.dg/goacc/routine-module-mod-1.f90: Likewise.
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