[Buildroot] buildroot still compiles C++ code when C++ compiler is unavailable

[Buildroot] buildroot still compiles C++ code when C++ compiler is unavailable

[Adam Nielsen]

Hi all,

After a successful build and changing some settings, I'm struggling to get a 
second successful build.  I had to select a newer version of GCC to avoid some 
segfaults, but now when compiling I get these errors:

checking whether to build shared libraries... yes
checking whether to build static libraries... yes
checking how to run the C++ preprocessor... /lib/cpp
configure: error: in 
`buildroot/build/gettext-0.18.2.1/gettext-runtime/libasprintf':
configure: error: C++ preprocessor "/lib/cpp" fails sanity check
See `config.log' for more details
configure: error: ./configure failed for libasprintf
configure: error: ./configure failed for gettext-runtime

According to Google it's because I don't have a C++ compiler installed, which 
is correct, I had originally compiled it, but then I deselected it in the 
buildroot config as the library was too big to fit in my device's flash memory.

I was assuming buildroot would now omit those packages that require C++, but 
it looks like I am wrong.  Is there an easy way to find out which packages 
depend on C++ and tell buildroot not to build them, now I have deselected C++ 
support?

Thanks,
Adam.

[Buildroot] buildroot still compiles C++ code when C++ compiler is unavailable

[Thomas Petazzoni]

Dear Adam Nielsen,

On Thu, 25 Apr 2013 14:46:05 +1000, Adam Nielsen wrote:

> After a successful build and changing some settings, I'm struggling
> to get a second successful build.  I had to select a newer version of
> GCC to avoid some segfaults, but now when compiling I get these
> errors:
> 
> checking whether to build shared libraries... yes
> checking whether to build static libraries... yes
> checking how to run the C++ preprocessor... /lib/cpp
> configure: error: in 
> `buildroot/build/gettext-0.18.2.1/gettext-runtime/libasprintf':
> configure: error: C++ preprocessor "/lib/cpp" fails sanity check
> See `config.log' for more details
> configure: error: ./configure failed for libasprintf
> configure: error: ./configure failed for gettext-runtime
> 
> According to Google it's because I don't have a C++ compiler
> installed, which is correct, I had originally compiled it, but then I
> deselected it in the buildroot config as the library was too big to
> fit in my device's flash memory.
> 
> I was assuming buildroot would now omit those packages that require
> C++, but it looks like I am wrong.  Is there an easy way to find out
> which packages depend on C++ and tell buildroot not to build them,
> now I have deselected C++ support?

All packages that depend on C++ have the 'depends on
BR2_INSTALL_LIBSTDCPP' dependency, so they are not selectable when C++
is not available.

However, did you do a complete 'make clean; make' cycle after disabling
C++ support? Buildroot doesn't track the configuration changes you're
making, so when you make a change as big in consequences as disabling
C++, you should do a complete rebuild.

Best regards,

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

[Buildroot] buildroot still compiles C++ code when C++ compiler is unavailable

[Adam Nielsen]

Hi Thomas,

Many thanks for your reply!

>> checking whether to build shared libraries... yes
>> checking whether to build static libraries... yes
>> checking how to run the C++ preprocessor... /lib/cpp
>> configure: error: in
>> `buildroot/build/gettext-0.18.2.1/gettext-runtime/libasprintf':
>> configure: error: C++ preprocessor "/lib/cpp" fails sanity check
>> See `config.log' for more details
>> configure: error: ./configure failed for libasprintf
>> configure: error: ./configure failed for gettext-runtime
>
> However, did you do a complete 'make clean; make' cycle after disabling
> C++ support? Buildroot doesn't track the configuration changes you're
> making, so when you make a change as big in consequences as disabling
> C++, you should do a complete rebuild.

Ahh ok, well that makes more sense, but yes, I did do a 'make clean' as part 
of trying to solve the problem.  I have just done it again to make absolutely 
sure, and I'm still getting the same error.

I've uploaded my .config here if it will help:

   http://www.shikadi.net/files/buildroot/2013-04-26.gettext_cpp_fails.config

Let me know if you can figure out what I have done wrong!

Thanks again,
Adam.