Rollup merge of #121085 - davidtwco:always-eager-diagnostics, r=nnethercote

errors: only eagerly translate subdiagnostics

Subdiagnostics don't need to be lazily translated, they can always be eagerly translated. Eager translation is slightly more complex as we need to have a `DiagCtxt` available to perform the translation, which involves slightly more threading of that context.

This slight increase in complexity should enable later simplifications - like passing `DiagCtxt` into `AddToDiagnostic` and moving Fluent messages into the diagnostic structs rather than having them in separate files (working on that was what led to this change).

r? ```@nnethercote```

1 files changed, 5 insertions, 5 deletions

diff --git a/compiler/rustc_session/src/parse.rs b/compiler/rustc_session/src/parse.rs
index 288e0a5ca6f..701c5bf375f 100644
--- a/compiler/rustc_session/src/parse.rs
+++ b/compiler/rustc_session/src/parse.rs
@@ -173,21 +173,21 @@ pub fn add_feature_diagnostics_for_issue(
     feature_from_cli: bool,
 ) {
     if let Some(n) = find_feature_issue(feature, issue) {
-        err.subdiagnostic(FeatureDiagnosticForIssue { n });
+        err.subdiagnostic(sess.dcx(), FeatureDiagnosticForIssue { n });
     }
 
     // #23973: do not suggest `#![feature(...)]` if we are in beta/stable
     if sess.parse_sess.unstable_features.is_nightly_build() {
         if feature_from_cli {
-            err.subdiagnostic(CliFeatureDiagnosticHelp { feature });
+            err.subdiagnostic(sess.dcx(), CliFeatureDiagnosticHelp { feature });
         } else {
-            err.subdiagnostic(FeatureDiagnosticHelp { feature });
+            err.subdiagnostic(sess.dcx(), FeatureDiagnosticHelp { feature });
         }
 
         if sess.opts.unstable_opts.ui_testing {
-            err.subdiagnostic(SuggestUpgradeCompiler::ui_testing());
+            err.subdiagnostic(sess.dcx(), SuggestUpgradeCompiler::ui_testing());
         } else if let Some(suggestion) = SuggestUpgradeCompiler::new() {
-            err.subdiagnostic(suggestion);
+            err.subdiagnostic(sess.dcx(), suggestion);
         }
     }
 }