Use std::io::Error and remove useless to_string

Author: adriantombu

compiler/rustc_driver/src/lib.rs

@@ -586,12 +586,12 @@ pub fn try_process_rlink(sess: &Session, compiler: &interface::Compiler) -> Comp
             sess.init_crate_types(collect_crate_types(sess, &[]));
             let outputs = compiler.build_output_filenames(sess, &[]);
             let rlink_data = fs::read(file).unwrap_or_else(|err| {
-                sess.emit_fatal(RlinkUnableToRead { error_message: err.to_string() });
+                sess.emit_fatal(RlinkUnableToRead { err });
             });
             let codegen_results = match CodegenResults::deserialize_rlink(rlink_data) {
                 Ok(codegen) => codegen,
-                Err(error) => {
-                    sess.emit_fatal(RlinkUnableToDeserialize { error_message: error.to_string() });
+                Err(error_message) => {
+                    sess.emit_fatal(RlinkUnableToDeserialize { error_message });
                 }
             };
             let result = compiler.codegen_backend().link(sess, codegen_results, &outputs);

compiler/rustc_driver/src/session_diagnostics.rs

@@ -3,7 +3,7 @@ use rustc_macros::SessionDiagnostic;
 #[derive(SessionDiagnostic)]
 #[diag(driver::rlink_unable_to_read)]
 pub(crate) struct RlinkUnableToRead {
-    pub error_message: String,
+    pub err: std::io::Error,
 }
 
 #[derive(SessionDiagnostic)]
@@ -14,4 +14,4 @@ pub(crate) struct RlinkUnableToDeserialize {
 
 #[derive(SessionDiagnostic)]
 #[diag(driver::rlink_no_a_file)]
-pub(crate) struct RlinkNotAFile {}
+pub(crate) struct RlinkNotAFile;

compiler/rustc_error_messages/locales/en-US/driver.ftl

@@ -1,4 +1,4 @@
-driver_rlink_unable_to_read = failed to read rlink file: `{$error_message}`
+driver_rlink_unable_to_read = failed to read rlink file: `{$err}`
 
 driver_rlink_unable_to_deserialize = could not deserialize .rlink file: `{$error_message}`