[PATCH] Prevent GCC 6 <cstdlib> from including /usr/include/stdlib.h

[Florian Weimer]

On 06/08/2016 10:03 PM, Carlos O'Donell wrote:
> On 06/08/2016 11:08 AM, Florian Weimer wrote:
>> Otherwise, /usr/include/stdlib.h turns up as a make dependency,
>> and an implicit rule will kick and make will try to install
>> stdlib/stdlib.h as /usr/include/stdlib.h because the target
>> is out of date.
>>
>> 2016-06-08  Florian Weimer  <fweimer@redhat.com>
>>
>> 	Prevent GCC 6 <cstdlib> from including /usr/include/stdlib.h.
>> 	* stdlib/tst-quick_exit.cc: Include <stdlib.h> before <cstdlib>.
>> 	* stdlib/tst-thread-quick_exit.cc: Likewise.
>
> OK, with source code comment explaining why 'stdlib.h' is being included.

I must have botched my initial testing.  Including <stdlib.h> first does 
not fix this problem.  It seems the only way is to use <stdlib.h> 
exclusively and drop the std:: namespace usage, and use <pthread.h> 
instead of <thread>. (<thread> indirectly pulls in 
/usr/include/c++/6.1.1/ext/string_conversions.h, which includes <cstdlib>).

 > What's going to be our long-term solution to this problem?

Merge the C and C++ run-time library implementations. :)

Various kludges are possible: List the GCC default search paths, patch 
them, and specify them along with -nostdinc.  Do not use #include_next, 
but an #include with an absolute path, where the path prefix can be 
configured with a preprocessor macro (#include arguments are subject to 
macro expansion, although this feature is used rarely).  I'll ask 
Jonathan, maybe he has some ideas.

Florian