TrigServices: Fixes for clang compilation / cmake fixes (!27804) · Merge requests · atlas / athena · GitLab

Scott Snyder requested to merge ssnyder/athena:clang.TrigServices-20191107 into master Nov 07, 2019

Address of a reference can never be null.
Missing override keyword
Work around misdeclared output operator in CTPfragment that was causing compilation with clang to fail.
Add missing dependency on AthenaMonitoring.
Fix placement of NO_PUBLIC_HEADERS keyword.