replace specialization with try_as_dyn

Author: dimpolo

partialdebug-derive/src/lib.rs

@@ -52,7 +52,7 @@ fn gen_field_as_debug_non_exhaustive(field: &Field) -> TokenStream2 {
     let name = &field.ident;
 
     quote! {
-        match ::partialdebug::specialization::AsDebug::as_debug(&self. #name) {
+        match ::core::any::try_as_dyn::<_, dyn ::core::fmt::Debug>(&self. #name) {
             ::core::option::Option::None => {
                 __exhaustive = false;
             }
@@ -213,7 +213,7 @@ fn gen_field_as_debug_placeholder(
     quote! {
         .field(
             #name_arg
-            match ::partialdebug::specialization::AsDebug::as_debug(&#field_handle){
+            match ::core::any::try_as_dyn::<_, dyn ::core::fmt::Debug>(&#field_handle){
                 ::core::option::Option::None => &::partialdebug::Placeholder(#placeholder_string),
                 ::core::option::Option::Some(__field) => __field,
             },

src/lib.rs

@@ -88,7 +88,7 @@
 //! ### Caveats
 //!
 //! Trait detection for generic types requires specialization.
-//! To enable specialization based trait detection use a nightly compiler and enable the `unstable` feature.
+//! To enable specialization based trait detection, use a nightly compiler and enable the `unstable` feature.
 //!
 //! ```
 //! use partialdebug::placeholder::PartialDebug;
@@ -104,8 +104,7 @@
 
 #![no_std]
 #![warn(missing_docs, trivial_casts, rust_2018_idioms)]
-#![cfg_attr(feature = "unstable", allow(incomplete_features))]
-#![cfg_attr(feature = "unstable", feature(specialization))]
+#![cfg_attr(feature = "unstable", feature(try_as_dyn))]
 
 use core::fmt::{Debug, Formatter, Result};
 
@@ -124,9 +123,6 @@ impl Debug for Placeholder {
 
 #[cfg(any(not(feature = "unstable"), doc))]
 pub mod no_specialization;
-/// Trait detection logic using specialization
-#[cfg(feature = "unstable")]
-pub mod specialization;
 
 /// The placeholder version of `PartialDebug`
 pub mod placeholder {

src/specialization.rs

@@ -1,6 +1,7 @@
 #![no_implicit_prelude]
 #![no_std]
 #![allow(dead_code)]
+#![cfg_attr(feature = "unstable", feature(try_as_dyn))]
 
 use ::partialdebug;
 

tests/hygiene.rs

@@ -1,3 +1,5 @@
+#![cfg_attr(feature = "unstable", feature(try_as_dyn))]
+
 mod partial {
     use partialdebug::placeholder::PartialDebug;