Remove unused method CodegenBackend::diagnostics

Author: bjorn3

src/librustc_codegen_llvm/lib.rs

@@ -258,10 +258,6 @@ impl CodegenBackend for LlvmCodegenBackend {
         llvm_util::print_version();
     }
 
-    fn diagnostics(&self) -> &[(&'static str, &'static str)] {
-        &error_codes::DIAGNOSTICS
-    }
-
     fn target_features(&self, sess: &Session) -> Vec<Symbol> {
         target_features(sess)
     }

src/librustc_codegen_utils/codegen_backend.rs

@@ -25,7 +25,6 @@ pub trait CodegenBackend {
     fn target_features(&self, _sess: &Session) -> Vec<Symbol> { vec![] }
     fn print_passes(&self) {}
     fn print_version(&self) {}
-    fn diagnostics(&self) -> &[(&'static str, &'static str)] { &[] }
 
     fn metadata_loader(&self) -> Box<dyn MetadataLoader + Sync>;
     fn provide(&self, _providers: &mut Providers<'_>);