[Scons-users] Tracing the loading of SConscript files

[Stefan Seefeld]

On 23.12.2015 12:56, Bill Deegan wrote:
> Stefen,

Bill,

thanks for the quick reply !

>
> First I'd try --debug=stacktrace
> See if that yields you anything.

That shows me where the error was raised, and allowed me to inject print
statements into the FS.VariantDir() method (as well as my SConscript files).
Now, when I run `scons -n` I see:

scons: Reading SConscript files ...
invoking VariantDir(src_dir=".",
variant_dir=#/bin.SCons/libs/release/dynamic/threading-multi,
duplicate=False
VariantDir(variant-dir=threading-multi, source_dir=boost.python)
invoking VariantDir(src_dir=./build, variant_dir=./src, duplicate=False
VariantDir(variant-dir=src, source_dir=build)
Checking for C header file Python.h... (cached) yes
invoking VariantDir(src_dir=".",
variant_dir=#/bin.SCons/libs/release/static/threading-multi, duplicate=False
VariantDir(variant-dir=threading-multi, source_dir=boost.python)
invoking VariantDir(src_dir=./build, variant_dir=./src, duplicate=False
VariantDir(variant-dir=src, source_dir=build)
scons: done reading SConscript files.
...

However, when I run `scons --test -n` I get:

scons: Reading SConscript files ...
invoking VariantDir(src_dir=".",
variant_dir=#/bin.SCons/libs/release/dynamic/threading-multi,
duplicate=False
VariantDir(variant-dir=threading-multi, source_dir=boost.python)
invoking VariantDir(src_dir=./build, variant_dir=./src, duplicate=False
VariantDir(variant-dir=src, source_dir=build)
Checking for C header file Python.h... (cached) yes
invoking VariantDir(src_dir=".",
variant_dir=#/bin.SCons/libs/release/static/threading-multi, duplicate=False
VariantDir(variant-dir=threading-multi, source_dir=.)

scons: *** Source directory cannot be under variant directory.

Notice the "source_dir=." in the last VariantDir invocation, which
differs from the equivalent call of `scons -n` above (i.e., without --test`.
There is an additional SConscript file that's loaded with --test, and I
verified that if I don't read that (i.e., invoke 'Return()' above
everything else), I don't get the error. This suggests that somehow the
content of that SConscript file might have corrupted the internal state
of the build system, and I need to figure out what. (That SConscript
file is here:
https://github.com/stefanseefeld/boost.python/blob/scons/test/SConscript)

>
> Can you provide a simple set of SConstruct/SConscripts which
> reproduces this?

I may try to reduce the problem to something manageable. For now I have
checked in the full set of build scripts into my boost.python repo (the
"scons" branch), which you can find (and clone) here:
https://github.com/stefanseefeld/boost.python/tree/scons

And a related question: What is the exact semantic of the 'VariantDir'
function ? I understand the general purpose, but I'm not sure what it
specifically does, in particular if I invoke it multiple times one after
another. Is the effect accumulated (say, the variant_dir values are
concatenated) ? Or does the second override the former ?

Thanks,
        Stefan

-- 

      ...ich hab' noch einen Koffer in Berlin...