document compilationunits.sh

diff --git a/qcsrc/tools/compilationunits.sh b/qcsrc/tools/compilationunits.sh
index d8086704e1193b7799de8b34a774aac24a2f7904..a43185b16c952c8e9247ceb68749353c4bd981d8 100755 (executable)
--- a/qcsrc/tools/compilationunits.sh
+++ b/qcsrc/tools/compilationunits.sh
@@ -2,9 +2,13 @@
 set -eu
 cd ${0%/*}
 
-# if these files exist from previous compilation, `./all compile` will stop
+# This script attempts to build the codebase in every possible header configuration,
+# to check that all files #include what they need, so that we can eventually move away
+# from a unity build and into incremental compilation.
+
+# If these files exist from previous compilation, `./all compile` will stop
 # detecting changes after running this script so delete them to trigger
-# a recompile next time
+# a recompile next time.
 if [ -f ../../csprogs.dat ]; then
     rm ../../csprogs.dat
 fi