+/// The 'location' at which we try to perform HIR-based wf checking.
+/// This information is used to obtain an `hir::Ty`, which
+/// we can walk in order to obtain precise spans for any
+/// 'nested' types (e.g. `Foo` in `Option<Foo>`).
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
+pub enum WellFormedLoc {
+ /// Use the type of the provided definition.
+ Ty(LocalDefId),
+ /// Use the type of the parameter of the provided function.
+ /// We cannot use `hir::Param`, since the function may
+ /// not have a body (e.g. a trait method definition)
+ Param {
+ /// The function to lookup the parameter in
+ function: LocalDefId,
+ /// The index of the parameter to use.
+ /// Parameters are indexed from 0, with the return type
+ /// being the last 'parameter'
+ param_idx: u16,
+ },
+}
+