gcc/fortran/doc/gfc-internals/command-line-options.rst

   1 ..
   2   Copyright 1988-2022 Free Software Foundation, Inc.
   3   This is part of the GCC manual.
   4   For copying conditions, see the copyright.rst file.
   5
   6 .. _command-line-options:
   7
   8 Command-Line Options
   9 ********************
  10
  11 Command-line options for :command:`gfortran` involve four interrelated
  12 pieces within the Fortran compiler code.
  13
  14 The relevant command-line flag is defined in :samp:`lang.opt`, according
  15 to the documentation in :ref:`gccint:options`.  This is then processed by the overall GCC
  16 machinery to create the code that enables :command:`gfortran` and
  17 :command:`gcc` to recognize the option in the command-line arguments and
  18 call the relevant handler function.
  19
  20 This generated code calls the ``gfc_handle_option`` code in
  21 :samp:`options.cc` with an enumerator variable indicating which option is
  22 to be processed, and the relevant integer or string values associated
  23 with that option flag.  Typically, ``gfc_handle_option`` uses these
  24 arguments to set global flags which record the option states.
  25
  26 The global flags that record the option states are stored in the
  27 ``gfc_option_t`` struct, which is defined in :samp:`gfortran.h`.
  28 Before the options are processed, initial values for these flags are set
  29 in ``gfc_init_option`` in :samp:`options.cc`; these become the default
  30 values for the options.