Warnings: remove defined but unused variables
Warnings: Ensure no QLOG_XYZ statements are on {}-less if statements

QLOG_XYZ are macros that evaluate to an if..else statement.  If you use them with a {}-less if statement, then you get dangling else clauses which the compiler warns about
Warnings: initialize variables before they are referenced
Warnings: Explicitly create virtual destructors when other virtual methods exist
Warnings: eliminate unused static functions
Warnings: eliminate spurious if statements that are always false
Warnings: Flag all unused parameters using Q_UNUSED
Warnings: cast all QVariant::type() results to QMetaType::Type