"info:/gcc/Warning Options" mentions -Werror, that treats all warnings as errors and -Werror-implicit-function-declaration, which treats implicit function declarations as errors but it does not mention how to treat other certain kinds of warnings as errors. For example -Werror-shadow does not work. This is because the feature is not generally implemented (only implemented specifically for implicit-function-declaration).
-- Summary: Implement -Werror for each kind of warning Product: gcc Version: 4.1.1 Status: UNCONFIRMED Severity: enhancement Priority: P3 Component: other AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: sigra at home dot se http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29768