Fix a comment typo

It ain't much, but it's honest work.

Author: jumbatm

src/librustc/mir/interpret/queries.rs

@@ -9,7 +9,7 @@ use rustc_span::Span;
 impl<'tcx> TyCtxt<'tcx> {
     /// Evaluates a constant without providing any substitutions. This is useful to evaluate consts
     /// that can't take any generic arguments like statics, const items or enum discriminants. If a
-    /// generic parameter is used within the constant `ErrorHandled::ToGeneric` will be returned.
+    /// generic parameter is used within the constant `ErrorHandled::TooGeneric` will be returned.
     pub fn const_eval_poly(self, def_id: DefId) -> ConstEvalResult<'tcx> {
         // In some situations def_id will have substitutions within scope, but they aren't allowed
         // to be used. So we can't use `Instance::mono`, instead we feed unresolved substitutions