Rollup merge of #121669 - nnethercote:count-stashed-errs-again, r=estebank

Count stashed errors again

Stashed diagnostics are such a pain. Their "might be emitted, might not" semantics messes with lots of things.

#120828 and #121206 made some big changes to how they work, improving some things, but still leaving some problems, as seen by the issues caused by #121206. This PR aims to fix all of them by restricting them in a way that eliminates the "might be emitted, might not" semantics while still allowing 98% of their benefit. Details in the individual commit logs.

r? `@oli-obk`

1 files changed, 15 insertions, 14 deletions

diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index f5a7bfd42ff..316a9c4f8df 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -1762,24 +1762,25 @@ impl<'a> Parser<'a> {
         err: impl FnOnce(&Self) -> Diag<'a>,
     ) -> L {
         assert!(could_be_unclosed_char_literal(ident));
-        if let Some(diag) = self.dcx().steal_diagnostic(ident.span, StashKey::LifetimeIsChar) {
-            diag.with_span_suggestion_verbose(
-                ident.span.shrink_to_hi(),
-                "add `'` to close the char literal",
-                "'",
-                Applicability::MaybeIncorrect,
-            )
-            .emit();
-        } else {
-            err(self)
-                .with_span_suggestion_verbose(
+        self.dcx()
+            .try_steal_modify_and_emit_err(ident.span, StashKey::LifetimeIsChar, |err| {
+                err.span_suggestion_verbose(
                     ident.span.shrink_to_hi(),
                     "add `'` to close the char literal",
                     "'",
                     Applicability::MaybeIncorrect,
-                )
-                .emit();
-        }
+                );
+            })
+            .unwrap_or_else(|| {
+                err(self)
+                    .with_span_suggestion_verbose(
+                        ident.span.shrink_to_hi(),
+                        "add `'` to close the char literal",
+                        "'",
+                        Applicability::MaybeIncorrect,
+                    )
+                    .emit()
+            });
         let name = ident.without_first_quote().name;
         mk_lit_char(name, ident.span)
     }