Remove unused DiagCtxt::span_bug_no_panic.

Author: nnethercote

compiler/rustc_errors/src/lib.rs

@@ -1079,13 +1079,6 @@ impl DiagCtxt {
         inner.good_path_delayed_bugs.push(DelayedDiagnostic::with_backtrace(diagnostic, backtrace));
     }
 
-    #[track_caller]
-    pub fn span_bug_no_panic(&self, span: impl Into<MultiSpan>, msg: impl Into<DiagnosticMessage>) {
-        let mut diag = Diagnostic::new(Bug, msg);
-        diag.set_span(span);
-        self.emit_diagnostic(diag);
-    }
-
     #[track_caller]
     #[rustc_lint_diagnostics]
     pub fn span_note(&self, span: impl Into<MultiSpan>, msg: impl Into<DiagnosticMessage>) {