nobs should autodetect Cray XC

[Former user]

Currently nobs looks for the NERSC_HOST env var to infer the cc and CC compilers as good defaults. This should be generalized to sniff out any Cray XC.

[Former user]

Wondering if @bonachea has a good idea of the best way to do this.

[Dan Bonachea]

install uses $CRAY_PRGENVGNU to detect we are on Cray XC with the right module is loaded.

It also uses $CRAY_PRGENVCRAY and $CRAY_PRGENVINTEL to blacklist those compilers.

[Paul Hargrove]

I agree with Dan that those three env vars are reliable indications that the respective PrgEnv-{gnu,cray,intel} modules are loaded.

If one wants a compiler-independent indicator, then I would suggest checking if $CRAYPE_DIR is set.

We should also consider checking $CRAYPE_NETWORK_TARGET.
This will have the value aries on Edison and Cori, and the value gemini on ORNL's Titan.
When set to gemini we can either adapt or reject - I suggest reject for now since we've not tested upc++ on Titan.

[Paul Hargrove]

FYI: we should (time permitting) be able to test any changes on ALCF's Theta system (an XC like Cori).
Scott, Dan, John and I all have accounts there.

[Former user]

Fixed issue 73. nobs uses cc/CC compilers on all Crays, not just at NERSC.

→ <<cset 6e1fc7039940>>

[Paul Hargrove]

I've just now confirmed that the following works on ALCF's Theta:

hargrove@thetalogin5:~/upcxx> export CROSS=cray-aries-alps
hargrove@thetalogin5:~/upcxx> ./install ~/upcxx-install
[...]
UPC++ successfully installed
hargrove@thetalogin5:~/upcxx> export UPCXX_INSTALL=$HOME/upcxx-install
hargrove@thetalogin5:~/upcxx> make -C example/prog-guide/
[success]

I have not run anything.