library-to-library dependencies

[descampsa]

See arduino/Arduino#3877 for previous discussion.
The problem is that a library is not recompiled when the include list of the main sketch (or of another library) has changed, despite the compilation option (include paths) are modified.

Note that when library-to-library dependencies will be completely supported (#12), i think it will be harder to find a reasonnable case where it is really noticeable. The only one i can think of is the one suggested by matthijskooijman, with the conflicting secondary header files.

I still think however that the proposed solution (each library generates its own dependency list) would make more sense and avoid bad surprises in some corner cases.

[ffissore]

@descampsa can you provide an example sketch + libraries, even fake libraries?

[descampsa]

Sure, here you have a (very) minimal example:
https://app.box.com/s/jkk2bk01l2y3omfdcakdbyhnk8kfj72w

1. compile with #include <SoftwareSerial.h> commented in the sketch -> fail to find SoftwareSerial.h in Foo.cpp
2. uncomment #include <SoftwareSerial.h> -> compile fine
3. comment again -> still compile fine, because the library is not recompiled

If you want a real lib where this happened to me, see https://github.com/descampsa/ardyno.
You will have to replace the hacky #include <../../libraries/SoftwareSerial/SoftwareSerial.h> in DynamixelInterface.cpp to reproduce the same issue.

[ffissore]

Uhm I see. I'm looking for a clean solution. In the meanwhile, move #include <SoftwareSerial.h> to Foo.h as that will leverage current library to library dependency discovery

[ffissore]

Note to self: while this issue is still valid, it's not reproducible anymore with the given sketch, because arduino-builder is now able to discover SoftwareSerial dependency specified in Foo.cpp

[ffissore]

@descampsa while I couldn't replicate this any more thanks to the smarter dependency discovery algorithm, I've also added a step that DELETES previously compiled libraries files IF those libraries are no longer used. Fix will be available with next hourly build http://www.arduino.cc/en/Main/Software#hourly