Rollup merge of #121382 - nnethercote:rework-untranslatable_diagnostic-lint, r=davidtwco

Rework `untranslatable_diagnostic` lint

Currently it only checks calls to functions marked with `#[rustc_lint_diagnostics]`. This PR changes it to check calls to any function with an `impl Into<{D,Subd}iagnosticMessage>` parameter. This greatly improves its coverage and doesn't rely on people remembering to add `#[rustc_lint_diagnostics]`. It also lets us add `#[rustc_lint_diagnostics]` to a number of functions that don't have an `impl Into<{D,Subd}iagnosticMessage>`, such as `Diag::span`.

r? ``@davidtwco``

Author: matthiaskrgr

crates/hir-ty/src/layout.rs

@@ -1,5 +1,6 @@
 //! Compute the binary representation of a type
 
+use std::borrow::Cow;
 use std::fmt;
 
 use base_db::salsa::Cycle;
@@ -114,8 +115,8 @@ struct LayoutCx<'a> {
 impl<'a> LayoutCalculator for LayoutCx<'a> {
     type TargetDataLayoutRef = &'a TargetDataLayout;
 
-    fn delayed_bug(&self, txt: String) {
-        never!("{}", txt);
+    fn delayed_bug(&self, txt: impl Into<Cow<'static, str>>) {
+        never!("{}", txt.into());
     }
 
     fn current_data_layout(&self) -> &'a TargetDataLayout {