With this change, there's no need to verify if the submodule is initialized,
because the submodules in GIT_SUBMODULES are automatically initialized and
updated if necessary before the build tasks are performed.
One downside of this change is that Google Benchmark configuration is now done
only during build. However that is minor, since now there are easy ways to
separately build different targets and program groups, so that a fail in
benchmark build doesn't really affect the other targets.
There is an issue with gbenchmark and waf on Ubuntu (15.04 and 15.10, ). Waf doesn't link pthread to gbenchmark and linking failed :
````
[1652/1652] Linking build/linux/libraries/AP_Math/benchmarks/benchmark_matrix.linux
/home/khancyr/Workspace/APM/ardupilot/build/linux/gbenchmark/lib/libbenchmark.a(benchmark.cc.o): dans la fonction « benchmark::RunSpecifiedBenchmarks(benchmark::BenchmarkReporter*) »:
benchmark.cc:(.text+0x2e21): référence indéfinie vers « pthread_create »
/usr/bin/ld generated: référence indéfinie vers « pthread_create »
collect2: error: ld returned 1 exit status
Waf: Leaving directory `/home/khancyr/Workspace/APM/ardupilot/build/linux'
Build failed
-> task in 'benchmark_matrix.linux' failed (exit status 1):
{task 139784788162576: cxxprogram benchmark_matrix.cpp.1.o -> benchmark_matrix.linux}
['/usr/lib/ccache/g++', '-Wl,--gc-sections', 'libraries/AP_Math/benchmarks/benchmark_matrix.cpp.1.o', '-o', '/home/khancyr/Workspace/APM/ardupilot/build/linux/libraries/AP_Math/benchmarks/benchmark_matrix.linux', '-Wl,-Bstatic', '-L.', '-lap', '-Wl,-Bdynamic', '-L/home/khancyr/Workspace/APM/ardupilot/build/linux/gbenchmark/lib', '-lm', '-lpthread', '-lrt', '-lbenchmark']
`````
Adding 'pthread' to env.LIB_GBENCHMARK solve the issue
see https://github.com/diydrones/ardupilot/pull/3460 and https://github.com/diydrones/ardupilot/issues/3461
The cmake checks for gbenchmark need to run some code. Calling
_configure_cmake() only during build can potentially fail build. That would
happen in some cross-compilations for example.
If there's no variant configuration, then cfg.variant will be '', which will
make bldnode be cfg.bldnode. Thus, this patch prepare gbenchmark build for
variant builds and doesn't break the current build.
We can pass a list of possible binaries to find_program. This gives us a
better output while configuring:
Checking for program 'ninja, ninja-build' : /usr/bin/ninja-build
instead of:
Checking for program 'ninja' : not found
Checking for program 'ninja-build' : /usr/bin/ninja-build
Pierre Kancir
Gustavo Jose de Sousa
pkancir
khancyr
Lucas De Marchi