Start moving rustc_driver to SessionDiagnostic

compiler/rustc_driver/src/session_diagnostics.rs

@@ -0,0 +1,25 @@
+use rustc_macros::SessionDiagnostic;
+use rustc_span::Span;
+
+#[derive(SessionDiagnostic)]
+#[error(driver::rlink_unable_to_read)]
+pub(crate) struct RlinkUnableToRead {
+    #[primary_span]
+    pub span: Span,
+    pub error_message: String,
+}
+
+#[derive(SessionDiagnostic)]
+#[error(driver::rlink_unable_to_deserialize)]
+pub(crate) struct RlinkUnableToDeserialize {
+    #[primary_span]
+    pub span: Span,
+    pub error_message: String,
+}
+
+#[derive(SessionDiagnostic)]
+#[error(driver::rlink_no_a_file)]
+pub(crate) struct RlinkNotAFile {
+    #[primary_span]
+    pub span: Span,
+}