Improve handling of `tmp` variable name conflicts

1 files changed, 6 insertions, 2 deletions

diff --git a/compiler/rustc_parse/src/parser/diagnostics.rs b/compiler/rustc_parse/src/parser/diagnostics.rs
index 26ca018685e..dcb150f18aa 100644
--- a/compiler/rustc_parse/src/parser/diagnostics.rs
+++ b/compiler/rustc_parse/src/parser/diagnostics.rs
@@ -1325,13 +1325,17 @@ impl<'a> Parser<'a> {
         kind: IncDecRecovery,
         (pre_span, post_span): (Span, Span),
     ) {
+        let mut msg = format!("use `{}= 1` instead", kind.op.chr());
+        if base_src.trim() == "tmp" {
+            msg.push_str(" (rename `tmp` so it doesn't conflict with your variable)");
+        }
         err.multipart_suggestion(
-            &format!("use `{}= 1` instead", kind.op.chr()),
+            &msg,
             vec![
                 (pre_span, "{ let tmp = ".to_string()),
                 (post_span, format!("; {} {}= 1; tmp }}", base_src, kind.op.chr())),
             ],
-            Applicability::MachineApplicable,
+            Applicability::HasPlaceholders,
         );
     }