Rollup merge of #120488 - nnethercote:diag-lifetimes, r=oli-obk

Diagnostic lifetimes cleanups

Some diagnostic simplifications.

r? `@oli-obk`

compiler/rustc_const_eval/src/const_eval/error.rs

@@ -34,7 +34,7 @@ impl MachineStopType for ConstEvalErrKind {
     }
     fn add_args(
         self: Box<Self>,
-        adder: &mut dyn FnMut(std::borrow::Cow<'static, str>, DiagnosticArgValue<'static>),
+        adder: &mut dyn FnMut(std::borrow::Cow<'static, str>, DiagnosticArgValue),
     ) {
         use ConstEvalErrKind::*;
         match *self {

compiler/rustc_const_eval/src/errors.rs

@@ -906,7 +906,7 @@ impl ReportErrorExt for ResourceExhaustionInfo {
 }
 
 impl rustc_errors::IntoDiagnosticArg for InternKind {
-    fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
+    fn into_diagnostic_arg(self) -> DiagnosticArgValue {
         DiagnosticArgValue::Str(Cow::Borrowed(match self {
             InternKind::Static(Mutability::Not) => "static",
             InternKind::Static(Mutability::Mut) => "static_mut",