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

[Sven Barth]

Am 29.02.2012 00:31, schrieb Tomas Hajny:
> On 9 Feb 12, at 23:09, Sven Barth wrote:
>> On 09.02.2012 22:14, Mark Morgan Lloyd wrote:
>>> Sven Barth wrote:
>>>> 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...).
>>>
>>> One thing I'd caution about the environment is that Debian- and probably
>>> others- predefines a significant number of shell functions, which shows
>>> up in the output of the set command.
>>>
>>
>> If OPT or CROSSOPT is set in the environment already you might have
>> problems with compiling FPC at all (because it might contain
>> incompatible options) no matter whether we use it for output or not...
>
> To let Mark (and Sven) know - I tried to add support for this to the
> compiler but I couldn't make it to work for OPT. The approach is OK
> in general (apart from the limitation that the compiler may also be
> compiled without Makefiles and potential use of whatever options
> wouldn't be visible in that case, but that scenario is probably not
> important). However, our Makefiles process these variables in very
> complex way and the result is that OPT is always empty during the
> compiler compilation (probably due to line 360 in compiler/Makefile).
> I thought that LOCALOPT might be used instead (see line 355) but that
> didn't work either. See the attachment (it's the stage when I wanted
> to try printing LOCALOPT too). Even if I use the original sample
> program from Sven and rename it to pp.pas and replace the compiler
> source file with it (and fix the warnings which are treated as errors
> due to -Sew added by the Makefile ;-) ), I only get CROSSOPT printed
> and OPT showed as empty.
>
> So I ended up by only adding the note to the help page regarding -an
> dependency on -dEXTDEBUG...

Well... thanks for trying anyways ;)

Regards,
Sven