[Scons-users] Scons Implicity Dependency not found issue

[Hua Yanghao]

scons: *** [build/configs/pangu/usw/firmware/arch/pangu/test.os]
Implicit dependency
`build/configs/pangu/usw/firmware/arch/pangu/include/io.h' not found,
needed by target `build/configs/pangu/usw/firmware/arch/pangu/test.os'

I recently run into this odd problem, and it is very difficult to
reproduce. I did not explicitly enable the "implicit_cache" option
anywhere in my code. If I simply remove the build folder and then
re-build everything works as normal. the problem happens when there is
a old build, and then I pulled in some new code where this "test.c"
has included an additional header io.h and scons seems not re-scanning
the file by default.

I am using scons 3.0.1, is the implict_cache by default enabled there
and I have to disable it manually?

Thanks,
Yanghao Hua