[Scons-users] Overriding the default compilation behavior / supporting new compilers

[Bill Deegan]

See the manpage:

Before reading the *SConstruct* file, *scons* looks for a directory named
*site_scons* in various system directories (see below) and the directory
containing the *SConstruct* file; for each of those dirs which exists,
*site_scons* is prepended to sys.path, the file *site_scons/site_init.py*,
is evaluated if it exists, and the directory *site_scons/site_tools* is
prepended to the default toolpath if it exists. See the --no-site-dir and
--site-dir options for more details.

If  you have your own tool in site_scons/site_tools and then do
env.Tool('my_special_tool'), and there's my_special_tool.py in site_tools,
it should load it.



On Wed, Sep 27, 2017 at 9:30 AM, Hua Yanghao <huayanghao at gmail.com> wrote:

> Thanks Bill.
>
> So how scons actually finds xyz-cc / xyz-ar implementation in Tools or
> site_scons/sit_tools/ folder?
>
> Is it based on string matching (e.g. CC=xyz-cc)? I had a try this way
> but it is not working for me.
>
> BR, Yanghao
>
> On Wed, Sep 27, 2017 at 6:10 PM, Bill Deegan <bill at baddogconsulting.com>
> wrote:
> > Generally the compiler and linker are implemented as different tools as
> far
> > as SCons is concerned.
> > That said migrating your more complex logic into site_scons/__init__.py
> and
> > if appropriate different tools in site_scons/site_tools is wise.
> >
> > Regardless, if you care compiling C or C++, then basing your tools or
> > modifications to existing variables would be the simplest way to use your
> > cross compilers.
> >
> >
> >
> > On Wed, Sep 27, 2017 at 11:41 AM, Hua Yanghao <huayanghao at gmail.com>
> wrote:
> >>
> >> Thanks Dan.
> >>
> >> The problem is more with a customized AR command, where the current
> >> implementation inserts an "rc" after ar (e.g. ar rc ....).
> >> I guess I can still override the ARFLAG environment variable instead
> >> of appending to it.
> >>
> >> However as there are some default FLAGS in other cases I do not want
> >> to override, so it becomes fragmented as I have to consider every and
> >> each cases and consider if I should append to it or replace and
> >> append. In the end I thought it might be cleaner if I just write an
> >> implementation of this special compiler with generate/exists calls but
> >> I am not successful so far for scons to automatically discover it in
> >> site_scons/site_tools/ folder. e.g. instead of a centrally located
> >> huge if/else I want to split the logic into separate pieces just for
> >> the sake of easier maintenance in the future.
> >>
> >> BR, Yanghao
> >>
> >> On Wed, Sep 27, 2017 at 5:20 PM, Dan Čermák
> >> <dan.cermak at cgc-instruments.com> wrote:
> >> > Hi Yanghao,
> >> >
> >> > you can override the environment variable 'CCCOM' to tell scons how
> your
> >> > compiler behaves (based on some condition).
> >> >
> >> > For example:
> >> >
> >> > env = Environment()
> >> >
> >> > env["CC"] = os.getenv("CC") or "gcc"
> >> >
> >> > if env["CC"] == "xyz-cc":
> >> >    env["CCCOM"] = '$CC -c $CFLAGS $CCFLAGS $_CCCOMCOM $SOURCES'
> >> >
> >> > You can find the documentation of all these CC-something variables
> here:
> >> > http://scons.org/doc/1.0.1/HTML/scons-user/a4754.html
> >> > (the example I gave here is more or less copy-pasted from my
> SConstruct,
> >> > which I use to build a arm cortex m4 firmware with arm-none-eabi-gcc &
> >> > TI's armcl compiler)
> >> >
> >> > Hope this is what you wanted to know.
> >> >
> >> >
> >> > Cheers,
> >> >
> >> > Dan
> >> >
> >> > Hua Yanghao <huayanghao at gmail.com> writes:
> >> >
> >> >> Dear Scons Friends,
> >> >> I looked at https://bitbucket.org/scons/scons/wiki/ToolsForFools
> which
> >> >> is a good starting point explaining how to use scons to implement
> >> >> tools. However I am missing one part how scons is actually connecting
> >> >> the CC=xyz-cc to the tools/xyz-cc.py file. For cross-compilation
> (e.g.
> >> >> CC=arm-none-eabi-gcc) it just works (I assume it is using the GCC
> >> >> command line options).
> >> >>
> >> >> Assume I have a customized C compiler called xyz-cc which uses
> >> >> completely different command line options to generate object files
> and
> >> >> a customized library archiver xyz-ar for building static libraries.
> >> >> Instead of making a new builder name (e.g. xyzObject(),
> >> >> xyzStaticLibrary), how can I change the default behaviour of the
> >> >> Object/StaticLibrary/Program builder to use my customized compilation
> >> >> tool chain?
> >> >>
> >> >> Best Regards,
> >> >> Yanghao
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