Move some code from Compiler::enter to GlobalCtxt::finish

compiler/rustc_middle/src/error.rs

@@ -1,5 +1,5 @@
-use std::fmt;
-use std::path::PathBuf;
+use std::path::{Path, PathBuf};
+use std::{fmt, io};
 
 use rustc_errors::codes::*;
 use rustc_errors::{DiagArgName, DiagArgValue, DiagMessage};
@@ -18,6 +18,13 @@ pub struct DropCheckOverflow<'tcx> {
     pub overflow_ty: Ty<'tcx>,
 }
 
+#[derive(Diagnostic)]
+#[diag(middle_failed_writing_file)]
+pub struct FailedWritingFile<'a> {
+    pub path: &'a Path,
+    pub error: io::Error,
+}
+
 #[derive(Diagnostic)]
 #[diag(middle_opaque_hidden_type_mismatch)]
 pub struct OpaqueHiddenTypeMismatch<'tcx> {