When a binding is declared without a value, borrowck verifies that all
codepaths have *one* assignment to them to initialize them fully. If
there are any cases where a condition can be met that leaves the binding
uninitialized or we attempt to initialize a field of an unitialized
binding, we emit E0381.
We now look at all the statements that initialize the binding, and use
them to explore branching code paths that *don't* and point at them. If
we find *no* potential places where an assignment to the binding might
be missing, we display the spans of all the existing initializers to
provide some context.
The `rustc_lint_diagnostics` attribute is used by the diagnostic
translation/struct migration lints to identify calls where
non-translatable diagnostics or diagnostics outwith impls are being
created. Any function used in creating a diagnostic should be annotated
with this attribute so this commit adds the attribute to many more
functions.
Signed-off-by: David Wood <david.wood@huawei.com>
`MultiSpan` contains labels, which are more complicated with the
introduction of diagnostic translation and will use types from
`rustc_errors` - however, `rustc_errors` depends on `rustc_span` so
`rustc_span` cannot use types like `DiagnosticMessage` without
dependency cycles. Introduce a new `rustc_error_messages` crate that can
contain `DiagnosticMessage` and `MultiSpan`.
Signed-off-by: David Wood <david.wood@huawei.com>
