7f91697b50
This commit updates the signatures of all diagnostic functions to accept types that can be converted into a `DiagnosticMessage`. This enables existing diagnostic calls to continue to work as before and Fluent identifiers to be provided. The `SessionDiagnostic` derive just generates normal diagnostic calls, so these APIs had to be modified to accept Fluent identifiers. In addition, loading of the "fallback" Fluent bundle, which contains the built-in English messages, has been implemented. Each diagnostic now has "arguments" which correspond to variables in the Fluent messages (necessary to render a Fluent message) but no API for adding arguments has been added yet. Therefore, diagnostics (that do not require interpolation) can be converted to use Fluent identifiers and will be output as before.
The driver crate is effectively the "main" function for the rust
compiler. It orchestrates the compilation process and "knits together"
the code from the other crates within rustc. This crate itself does
not contain any of the "main logic" of the compiler (though it does
have some code related to pretty printing or other minor compiler
options).
For more information about how the driver works, see the rustc dev guide.