Avoid `struct_diagnostic` where possible.

It's necessary for `derive(Diagnostic)`, but is best avoided elsewhere
because there are clearer alternatives.

This required adding `Handler::struct_almost_fatal`.

2 files changed, 2 insertions, 11 deletions

diff --git a/compiler/rustc_session/src/errors.rs b/compiler/rustc_session/src/errors.rs
index 7eed59709c8..aab7595ef6e 100644
--- a/compiler/rustc_session/src/errors.rs
+++ b/compiler/rustc_session/src/errors.rs
@@ -19,7 +19,7 @@ impl<'a> IntoDiagnostic<'a> for FeatureGateError {
         self,
         handler: &'a rustc_errors::Handler,
     ) -> rustc_errors::DiagnosticBuilder<'a, ErrorGuaranteed> {
-        let mut diag = handler.struct_diagnostic(self.explain);
+        let mut diag = handler.struct_err(self.explain);
         diag.set_span(self.span);
         diag.code(error_code!(E0658));
         diag
diff --git a/compiler/rustc_session/src/parse.rs b/compiler/rustc_session/src/parse.rs
index 881e1de6755..525f00f5cd0 100644
--- a/compiler/rustc_session/src/parse.rs
+++ b/compiler/rustc_session/src/parse.rs
@@ -14,7 +14,7 @@ use rustc_data_structures::sync::{AppendOnlyVec, Lock, Lrc};
 use rustc_errors::{emitter::SilentEmitter, Handler};
 use rustc_errors::{
     fallback_fluent_bundle, Diagnostic, DiagnosticBuilder, DiagnosticId, DiagnosticMessage,
-    EmissionGuarantee, ErrorGuaranteed, IntoDiagnostic, MultiSpan, Noted, StashKey,
+    ErrorGuaranteed, IntoDiagnostic, MultiSpan, Noted, StashKey,
 };
 use rustc_feature::{find_feature_issue, GateIssue, UnstableFeatures};
 use rustc_span::edition::Edition;
@@ -390,13 +390,4 @@ impl ParseSess {
     pub fn struct_fatal(&self, msg: impl Into<DiagnosticMessage>) -> DiagnosticBuilder<'_, !> {
         self.span_diagnostic.struct_fatal(msg)
     }
-
-    #[rustc_lint_diagnostics]
-    #[track_caller]
-    pub fn struct_diagnostic<G: EmissionGuarantee>(
-        &self,
-        msg: impl Into<DiagnosticMessage>,
-    ) -> DiagnosticBuilder<'_, G> {
-        self.span_diagnostic.struct_diagnostic(msg)
-    }
 }