The Azoth compiler emits diagnostics for warnings, and both fatal and non-fatal errors.
Fatal compiler errors prevent the package from being compiled or debugged.
Errors should be categorized as fatal only when it is impossible for the compiler generate machine code. For example, a compiler error that a semicolon is missing should be non-fatal because the compiler can correctly compile the code by inserting the missing semicolon.
Non-fatal compiler errors still allow the package to be compiled for a debug build and or debugged. However, non-fatal compiler errors prevent compiling the package for release.
Errors should be categorized as non-fatal whenever possible. In addition, many diagnostics that would be warnings for other compilers should be non-fatal errors. Anything that would be a warning in another compiler that should not be ignored and are definitely incorrect should be non-fatal errors. For example, diagnostics about violations of naming conventions should be non-fatal errors.
Warnings indicate code that is very likely to be incorrect in some way but aren't definitely incorrect. However, it is very important that warnings should be generated only for things that are likely to be incorrect so that developers don't feel the need to ignore warnings.