[Scons-dev] Accommodating dependency cycles.

[Gary Oberbrunner]

On Wed, Mar 22, 2017 at 6:15 PM, William Blevins <wblevins001 at gmail.com>
wrote:

> //source.cpp
> #include "source.gen.h"
> int main() { return 0; }
>
> //SConstruct
> e = Environment()
> e.Command("source.gen.h", "source.cpp", Copy('$TARGET', '$SOURCE')) #
> "generator"
> e.Program("source.cpp")
>
> This code works fine in Scons 2.1, but Scons 2.5.1 produce error:
> scons: *** Found dependency cycle(s):
>   source.gen.h -> source.gen.h
>
> If I'm reading this correctly, I don't see a cycle.
"source" depends on source.cpp and source.gen.h.
source.gen.h depends on source.cpp.
source.cpp is a source, doesn't depend on anything.
Now source.gen.h includes itself, which is weird, but shouldn't all by
itself cause a loop as long as the scanner knows it's already seen that
file.
source.gen.h should definitely not depend on itself.

(Not saying the current code doesn't detect a cycle, just that in the
abstract there shouldn't actually be one.)


-- 
Gary
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