[fpc-pascal] OT: Listing fpc options Was: Using a custom fpc.cfg

[johanns at nacs.net]

On Tue, Jul 08, 2014 at 01:21:07PM +0200, Tomas Hajny wrote:
>On Tue, July 8, 2014 12:07, Mark Morgan Lloyd wrote:
>> Tomas Hajny wrote:
>>
>>>> Incidentally, how does one get a list of fpc's 
>>>> options? I don't mean fpc -h  since that actually 
>>>> shows ppcXXX's options, but how does one get minimal 
>>>> info on fpc itself such as a reminder of the -V 
>>>> option?
>>>
>>> In trunk, fpc -h shows all options supported by either 
>>> fpc or ppcXXX (technically, ppcXXX still shows the 
>>> list, but it includes fpc specific options if invoked 
>>> from fpc). The part handled specifically by fpc should 
>>> not be of such a high interest normally, but it may be 
>>> obtained by diffing the output of both.
>>
>> I agree that it's obscure, but there was discussion of -V a few weeks
>> ago in the context of starting Lazarus and I needed a reminder
>> yesterday. Looking at 2.6.4 source, I note also -PP and -PB with the
>> apparent "health warning" that they aren't qualified by the -V parameter.
>
>I meant specifically that most users should not need to differentiate
>between options handled by fpc and options handled by ppcXXX.
>
>Anyway - if you want to find out options specific to the fpc helper
>(and/or you don't have a compiled trunk compiler readily available), you
>can also use:
>
>grep -e "^F\*" < fpcsrc/compiler/msg/errore.msg  | cut -c3- |
>sed "s/^1/-/" | sed "s/^2/ -/" | sed "s/_/   /"

Yes, I should know better than to reply here on this, but 
I am fascinated by how this one line UNIX command can 
parse the error message source file and extract the option 
information.

In general would it be more efficient to combine all the 
sed commands into one with multiple -e options, saving the 
extra pipes between commands, or would there be drawbacks?

grep -e "^F\*" < fpcsrc/compiler/msg/errore.msg  | cut -c3- |
sed -e "s/^1/-/" -e "s/^2/ -/" -e "s/_/   /"

Apologies for being off-topic.  I am interested in what it 
is safely compatible to do across various environments in 
clever compile scripts.

>(again, you need the trunk version of errore.msg as available e.g. from
>http://svn.freepascal.org/cgi-bin/viewvc.cgi/trunk/compiler/msg/errore.msg?revision=28152&view=co)
>
>That gives the following list:
>
>-P<x>   Target CPU / compiler related options:
> -PB   Show default compiler binary
> -PP   Show default target cpu
> -P<x>   Set target CPU
>(arm,i386,m68k,mips,mipsel,powerpc,powerpc64,sparc,x86_64
>-V<x>   Append '-<x>' to the used compiler binary name (e.g. for version)
> -Xp<x>   First search for the compiler binary in the directory <x>
>
>Tomas