-an and help page (Was: Re: [fpc-devel] Re: Episode 4. Addressing and it's limits Part Two)

[Sven Barth]

On 09.02.2012 18:59, Mark Morgan Lloyd wrote:
> Tomas Hajny wrote:
>
>> Yes, this is what I suggested to do above; for -an, not in general,
>> because I don't know of such dependencies myself (I wasn't aware of it
>> for
>> -an either).
>>
>>
>>> (b) having a line in the banner showing what non-default options were
>>> used during build?
>>>
>>> Free Pascal Compiler version 2.7.1 [2012/02/06] for mipsel
>>> Copyright (c) 1993-2011 by Florian Klaempfl and others
>>> Built with EXTDEBUG, fvm32.
>>
>> I'm afraid that this is "a bit" more difficult _if_ we want a general
>> solution. Addressing individual options explicitly is possible (probably
>> line by line rather than as a list though). Obviously, this wouldn't be a
>> general solution. However, I'm not aware of any compiler macro
>> allowing to
>> list all conditional defines (that would be still the easier part,
>> because
>> these are obviously known within the compiler so adding a new macro
>> should
>> be possible, but it may be a long list), and even less a macro
>> allowing to
>> list just compiler defines added explicitly on the command line (rather
>> than defined internally for a particular target, implied from some other
>> command line options or defined within the respective source file)... I'd
>> wait for opinion of other core team members whether we should add support
>> for explicit "Built with EXTDEBUG" or do something else (but I'm
>> certainly
>> not the one who'd add a macro necessary for the general solution).
>
> I suppose another possibility would be to have something in the makefile
> that captured the shell/environment variables, in the same way that the
> Lazarus build captures the revision number if available. But that's not
> in the same league as putting useful info in the banner.
>
> I think a good starting point would be a line that showed any
> definitions that were known to have an effect on the interpretation of
> the options, e.g. EXTDEBUG and- in particular- the exact target CPU when
> this wasn't the default.
>

What about this (using an example application instead of the compiler):

=== source begin ===

program envtest;

const
   crossopt = {$include %CROSSOPT%};
   opt = {$include %OPT%};

begin
   Writeln('CROSSOPT: ', crossopt);
   Writeln('OPT: ', opt);
end.

=== source end ===

The Makefile used below just calls "fpc envtest.pp" for "all".

=== shell begin ===

[sven at artemis oneshots]% make all OPT="-dEXTDEBUG" CROSSOPT="-CfSSE2"
fpc envtest.pp
Free Pascal Compiler version 2.6.0 [2011/12/23] for i386
Copyright (c) 1993-2011 by Florian Klaempfl and others
Target OS: Linux for i386
Compiling envtest.pp
Linking envtest
/usr/bin/ld: warning: link.res contains output sections; did you forget -T?
10 lines compiled, 0.5 sec
[sven at artemis oneshots]% ./envtest
CROSSOPT: -CfSSE2
OPT: -dEXTDEBUG

=== shell end ===

For the explanation: make moves all variables into the environment which 
is inherited by the processes that are called by it. FPC can include the 
values of a environment variable at compile time (it will be '' if not 
set, though a warning will occur which needs to be disabled with $warn) 
and thus at least the values of OPT and CROSSOPT could be printed by the 
compiler (which should normally be sufficient...).

Regards,
Sven