ReFrame tutorial: missing -pthread in A Multithreaded “Hello, World!”

[akesandgren]

The initial Multithreaded “Hello, World!” most likely need a "-pthread" compiler flag. It is at least required for g++ 9.3.0.

Without it I get:

cat stage/generic/default/builtin/HelloThreadedTest/rfm_HelloThreadedTest_build.err 
/scratch/cc0LAYZw.o:hello_threads.cpp:function std::thread::thread<void (&)(int), int&, void>(void (&)(int), int&): error: undefined reference to 'pthread_create'
collect2: error: ld returned 1 exit status

[vkarak]

@akesandgren I don't know if this is a "bug." The tutorial examples are not entirely generic and need to be slightly adapted to each system. We're testing them continuously on Daint, but of course, this doesn't make them generic. Nonetheless, adding -pthread also in the examples might be harmless.

[akesandgren]

Adding -pthread would make it more (linux) generic since that's what a standard gcc requires, but it might require a comment that non-gcc (xlc, pgcc for instance) will have problem with it.

(And I didn't say it is a bug)

[vkarak]

Actually, I think the Cray wrappers do add the -pthread for you to keep things "simple" :-)