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``

compiler/rustc_session/src/config.rs

@@ -1,6 +1,8 @@
 //! Contains infrastructure for configuring the compiler, including parsing
 //! command-line options.
 
+#![allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
+
 pub use crate::options::*;
 
 use crate::errors::FileWriteFail;
@@ -2468,9 +2470,7 @@ pub fn parse_externs(
             ));
             let adjusted_name = name.replace('-', "_");
             if is_ascii_ident(&adjusted_name) {
-                // FIXME: make this translatable
-                #[allow(rustc::diagnostic_outside_of_impl)]
-                #[allow(rustc::untranslatable_diagnostic)]
+                #[allow(rustc::diagnostic_outside_of_impl)] // FIXME
                 error.help(format!(
                     "consider replacing the dashes with underscores: `{adjusted_name}`"
                 ));