[Bug-gnupress] Other questions about GCC

[Paul A. Crable]

First, I am struggling to get the big picture with GCC.
Perhaps you can help.

1.  At some time before GCC is executed it is configured
for a certain processor or architecture, and at the same
time certain options may be applied.

2.  The options I am editing, in 3.xx, are arguments
placed on the command line when GCC is executed.

3.  As the section is written, GCC can be invoked with no
options specified, or with one or more options specified.

4.  With rare exception, all of the arguments can be
applied to any configuratation of GCC

5.  If GCC is configured for, say, an 68010; simply by
specifying an option the user can generate the code for
any other target, such as an IBM RS/6000.

Please advise if my conception is correct.

Second, the way options are described in my section, 3.17,
is not uniform.  It appears there are three types of
options, and each option requires certain information.
These are the three types and the information each should
convey:

1.  BINARY.  A binary option is either on or off.  It is
off if the option is omitted, and on if the option is
specified.  The option is, therefore, off by default.

For these options we need to specify the normal behavior,
and the change of behavior if the option is specified.

2.  RADIO BUTTONS.  A radio button option takes one value
from a set of values; e.g., -option_A=set_of_values.

For these options we need to specify the action taken for
each acceptable value, the action taken if an inacceptable
value is specified, and the action taken if the argument
is omitted altogether (a.k.a. the default value)

3.  CONDITIONAL BINARY.  A conditional binary option takes
different values under different conditions.  Most often
this refers to the default condition, when the option is
unspecified.  For example, option -A may be the default if
a 68xxx processor is the target, and -noA otherwise.

For these types of options, we need to specify (1) the
normal, or default, operation that takes place if the
option is omitted, (2) the operation that takes place if
the option is specified, and (3) the default value under
every possible condition.

I would like to adopt this convention in the remainder of
my work on 3.17.