fix various dashboard issues
As noted in !3804 (merged) and additionally flagged by @ken-martin. The dashboard is complaining about a number of issues https://open.cdash.org/viewBuildError.php?type=1&buildid=5229459
Some of the warning are a matter of interpretation:
- string passing by value instead of by reference. Which should be acceptable OK for short string optimizations, but objectionable for large string.
The flagging of method
empty()
instead ofclear()
looks pretty odd - apparently doesn't deal with std containers.