Introduce two new compiler options (booc/nant/msbuild): -nowarn:BCW0001,... -warnaserror:BCW0001,... In the CompilerParameters, add four methods: SuppressWarning(string code) RestoreWarning(string code) PromoteWarningAsError(string code) RevokeWarningAsError(string code) Internally it uses Adding event on CompilerWarningCollection, however this provides an easier alternative wrt the suppression/promotion of warnings (especially wrt BOO-1126)