Failed to invoke nproc alias

[bradhowes]

(venv) howes% ./open_spiel/scripts/build_and_run_tests.sh
++ CXX=g++
++ [[ darwin18 == \d\a\r\w\i\n* ]]
++ alias 'nproc=sysctl -n hw.physicalcpu'
++ CXX=/usr/local/bin/g++-7
+++ nproc
./open_spiel/scripts/build_and_run_tests.sh: line 37: nproc: command not found
++ MAKE_NUM_PROCS=

Apparently nproc alias is not expanded in the build_and_run_tests.sh script in the $(nproc) expression. My fix:

diff --git a/open_spiel/scripts/build_and_run_tests.sh b/open_spiel/scripts/build_and_run_tests.sh
index ba0ec84..a4a64ab 100755
--- a/open_spiel/scripts/build_and_run_tests.sh
+++ b/open_spiel/scripts/build_and_run_tests.sh
@@ -29,13 +29,14 @@ set -e  # exit when any command fails
 set -x
 
 CXX=g++
+NPROC=nproc
 if [[ "$OSTYPE" == "darwin"* ]]; then  # Mac OSX
-  alias nproc="sysctl -n hw.physicalcpu"
+  NPROC="sysctl -n hw.physicalcpu"
   CXX=/usr/local/bin/g++-7
 fi
 
-MAKE_NUM_PROCS=$(nproc)
-let TEST_NUM_PROCS=4*$(nproc)
+MAKE_NUM_PROCS=$(${NPROC})
+let TEST_NUM_PROCS=4*${MAKE_NUM_PROCS}
 
 PYVERSION=$(python3 -c 'import sys; print(sys.version.split(" ")[0])')
 PY_VERSION_MAJOR=$(python3 -c 'import sys; print(sys.version_info.major)')

[lanctot]

Ah, thanks for this! We indeed have not tested on MacOS yet, so this is quite informative, thanks! Feel free to turn your change into a pull request.