Remove force_print_diagnostic.

There are a couple of places where we call
`inner.emitter.emit_diagnostic` directly rather than going through
`inner.emit_diagnostic`, to guarantee the diagnostic is printed. This
feels dubious to me, particularly the bypassing of `TRACK_DIAGNOSTIC`.

This commit removes those.
- In `print_error_count`, it uses `ForceWarning` instead of `Warning`.
- It removes `DiagCtxtInner::failure_note`, because it only has three
  uses and direct use of `emit_diagnostic` is consistent with other
  similar locations.
- It removes `force_print_diagnostic`, and adds `struct_failure_note`,
  and updates `print_query_stack` accordingly, which makes it more
  normal. That location doesn't seem to need forced printing anyway.

compiler/rustc_query_system/src/query/job.rs

@@ -4,7 +4,7 @@ use crate::query::plumbing::CycleError;
 use crate::query::DepKind;
 use crate::query::{QueryContext, QueryStackFrame};
 use rustc_data_structures::fx::FxHashMap;
-use rustc_errors::{DiagCtxt, Diagnostic, DiagnosticBuilder, Level};
+use rustc_errors::{DiagCtxt, DiagnosticBuilder};
 use rustc_hir::def::DefKind;
 use rustc_session::Session;
 use rustc_span::Span;
@@ -628,15 +628,15 @@ pub fn print_query_stack<Qcx: QueryContext>(
         };
         if Some(count_printed) < num_frames || num_frames.is_none() {
             // Only print to stderr as many stack frames as `num_frames` when present.
-            let mut diag = Diagnostic::new(
-                Level::FailureNote,
-                format!(
-                    "#{} [{:?}] {}",
-                    count_printed, query_info.query.dep_kind, query_info.query.description
-                ),
-            );
-            diag.span = query_info.job.span.into();
-            dcx.force_print_diagnostic(diag);
+            // FIXME: needs translation
+            #[allow(rustc::diagnostic_outside_of_impl)]
+            #[allow(rustc::untranslatable_diagnostic)]
+            dcx.struct_failure_note(format!(
+                "#{} [{:?}] {}",
+                count_printed, query_info.query.dep_kind, query_info.query.description
+            ))
+            .with_span(query_info.job.span)
+            .emit();
             count_printed += 1;
         }