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`.

1 files changed, 17 insertions, 2 deletions

diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index 3718fd535f5..4093daba4b4 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -722,7 +722,12 @@ impl Handler {
         self.inner.borrow_mut().emit_stashed_diagnostics()
     }
 
-    /// Construct a builder with the `msg` at the level appropriate for the specific `EmissionGuarantee`.
+    /// Construct a builder with the `msg` at the level appropriate for the
+    /// specific `EmissionGuarantee`.
+    ///
+    /// Note: this is necessary for `derive(Diagnostic)`, but shouldn't be used
+    /// outside of that. Instead use `struct_err`, `struct_warn`, etc., which
+    /// make the diagnostic kind clearer.
     #[rustc_lint_diagnostics]
     #[track_caller]
     pub fn struct_diagnostic<G: EmissionGuarantee>(
@@ -937,13 +942,23 @@ impl Handler {
         result
     }
 
-    /// Construct a builder at the `Error` level with the `msg`.
+    /// Construct a builder at the `Fatal` level with the `msg`.
     #[rustc_lint_diagnostics]
     #[track_caller]
     pub fn struct_fatal(&self, msg: impl Into<DiagnosticMessage>) -> DiagnosticBuilder<'_, !> {
         DiagnosticBuilder::new(self, Level::Fatal, msg)
     }
 
+    /// Construct a builder at the `Fatal` level with the `msg`, that doesn't abort.
+    #[rustc_lint_diagnostics]
+    #[track_caller]
+    pub fn struct_almost_fatal(
+        &self,
+        msg: impl Into<DiagnosticMessage>,
+    ) -> DiagnosticBuilder<'_, FatalError> {
+        DiagnosticBuilder::new(self, Level::Fatal, msg)
+    }
+
     /// Construct a builder at the `Help` level with the `msg`.
     #[rustc_lint_diagnostics]
     pub fn struct_help(&self, msg: impl Into<DiagnosticMessage>) -> DiagnosticBuilder<'_, ()> {