flang-new requires -cpp flag for preprocessing, unlike other compilers

[gha3mi]

Description

When using fpm with flang-new, the -cpp flag must be passed manually for preprocessing to work. This is not required with other compilers.

Test case:

program check
#if defined(TEST)
   print *, "This is a test"
#endif
end program

Running:

fpm test --compiler flang-new --flag "-DTEST"

results in:

./test/check.f90:2:12: error: excess characters after expression
  #if defined(TEST)
             ^^^^^^
<ERROR> Compilation failed for object " test_check.f90.o "
<ERROR> stopping due to failed compilation
STOP 1

However, this works as expected:

fpm test --compiler flang-new --flag "-cpp -DTEST"

Expected Behaviour

As suggested here by @perazz, including -cpp by default for flang-new should resolve this issue.

fpm test --compiler flang-new --flag "-DTEST"

Version of fpm

0.12.0, alpha

Platform and Architecture

Tested on Linux

Additional Information

No response