Rewrite on_unimplemented format string parser.

compiler/rustc_span/src/hygiene.rs

@@ -1270,6 +1270,25 @@ impl DesugaringKind {
  DesugaringKind::PatTyRange => "pattern type",
  }
  }
+
+ /// For use with `rustc_unimplemented` to support conditions
+ /// like `from_desugaring = "QuestionMark"`
+ pub fn matches(&self, value: &str) -> bool {
+ match self {
+ DesugaringKind::CondTemporary => value == "CondTemporary",
+ DesugaringKind::Async => value == "Async",
+ DesugaringKind::Await => value == "Await",
+ DesugaringKind::QuestionMark => value == "QuestionMark",
+ DesugaringKind::TryBlock => value == "TryBlock",
+ DesugaringKind::YeetExpr => value == "YeetExpr",
+ DesugaringKind::OpaqueTy => value == "OpaqueTy",
+ DesugaringKind::ForLoop => value == "ForLoop",
+ DesugaringKind::WhileLoop => value == "WhileLoop",
+ DesugaringKind::BoundModifier => value == "BoundModifier",
+ DesugaringKind::Contract => value == "Contract",
+ DesugaringKind::PatTyRange => value == "PatTyRange",
+ }
+ }
 }
 
 #[derive(Default)]

compiler/rustc_span/src/symbol.rs

@@ -372,6 +372,7 @@ symbols! {
  SyncUnsafeCell,
  T,
  Target,
+ This,
  ToOwned,
  ToString,
  TokenStream,

compiler/rustc_trait_selection/src/error_reporting/traits/mod.rs

@@ -2,6 +2,8 @@ pub mod ambiguity;
 pub mod call_kind;
 mod fulfillment_errors;
 pub mod on_unimplemented;
+pub mod on_unimplemented_condition;
+pub mod on_unimplemented_format;
 mod overflow;
 pub mod suggestions;