Split `Handler::emit_diagnostic` in two.

Currently, `emit_diagnostic` takes `&mut self`.

This commit changes it so `emit_diagnostic` takes `self` and the new
`emit_diagnostic_without_consuming` function takes `&mut self`.

I find the distinction useful. The former case is much more common, and
avoids a bunch of `mut` and `&mut` occurrences. We can also restrict the
latter with `pub(crate)` which is nice.

1 files changed, 2 insertions, 2 deletions

diff --git a/compiler/rustc_const_eval/src/transform/check_consts/check.rs b/compiler/rustc_const_eval/src/transform/check_consts/check.rs
index 5380d3071d6..bb17602d3ba 100644
--- a/compiler/rustc_const_eval/src/transform/check_consts/check.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/check.rs
@@ -277,8 +277,8 @@ impl<'mir, 'tcx> Checker<'mir, 'tcx> {
         // "secondary" errors if they occurred.
         let secondary_errors = mem::take(&mut self.secondary_errors);
         if self.error_emitted.is_none() {
-            for mut error in secondary_errors {
-                self.tcx.sess.diagnostic().emit_diagnostic(&mut error);
+            for error in secondary_errors {
+                self.tcx.sess.diagnostic().emit_diagnostic(error);
             }
         } else {
             assert!(self.tcx.sess.has_errors().is_some());