Auto merge of #62507 - petrochenkov:macunstab, r=alexcrichton

Remove derives `Encodable`/`Decodable` and unstabilize attribute `#[bench]`

`Encodable` and `Decodable` were deprecated before 1.0 and emitted an unsuppressable warning all this time.
`#[bench]` is a part of the custom test framework feature and cannot be used meaningfully on stable, only as `cfg(false)`.

Crater results can be found in https://github.com/rust-lang/rust/pull/62507#issuecomment-513850732 and below.

This PR also reroutes the tracking issue for `feature(test)` from #27812 (compiler internals) to #50297 (custom test frameworks).

Closes https://github.com/rust-lang/rust/issues/62048

3 files changed, 2 insertions, 36 deletions

diff --git a/src/libsyntax_ext/deriving/decodable.rs b/src/libsyntax_ext/deriving/decodable.rs
index 8009f42b8cf..4c0641d08a9 100644
--- a/src/libsyntax_ext/deriving/decodable.rs
+++ b/src/libsyntax_ext/deriving/decodable.rs
@@ -17,23 +17,7 @@ pub fn expand_deriving_rustc_decodable(cx: &mut ExtCtxt<'_>,
                                        mitem: &MetaItem,
                                        item: &Annotatable,
                                        push: &mut dyn FnMut(Annotatable)) {
-    expand_deriving_decodable_imp(cx, span, mitem, item, push, "rustc_serialize")
-}
-
-pub fn expand_deriving_decodable(cx: &mut ExtCtxt<'_>,
-                                 span: Span,
-                                 mitem: &MetaItem,
-                                 item: &Annotatable,
-                                 push: &mut dyn FnMut(Annotatable)) {
-    expand_deriving_decodable_imp(cx, span, mitem, item, push, "serialize")
-}
-
-fn expand_deriving_decodable_imp(cx: &mut ExtCtxt<'_>,
-                                 span: Span,
-                                 mitem: &MetaItem,
-                                 item: &Annotatable,
-                                 push: &mut dyn FnMut(Annotatable),
-                                 krate: &'static str) {
+    let krate = "rustc_serialize";
     let typaram = &*deriving::hygienic_type_parameter(item, "__D");
 
     let trait_def = TraitDef {
diff --git a/src/libsyntax_ext/deriving/encodable.rs b/src/libsyntax_ext/deriving/encodable.rs
index cd89a42cf82..a964a0970f0 100644
--- a/src/libsyntax_ext/deriving/encodable.rs
+++ b/src/libsyntax_ext/deriving/encodable.rs
@@ -98,23 +98,7 @@ pub fn expand_deriving_rustc_encodable(cx: &mut ExtCtxt<'_>,
                                        mitem: &MetaItem,
                                        item: &Annotatable,
                                        push: &mut dyn FnMut(Annotatable)) {
-    expand_deriving_encodable_imp(cx, span, mitem, item, push, "rustc_serialize")
-}
-
-pub fn expand_deriving_encodable(cx: &mut ExtCtxt<'_>,
-                                 span: Span,
-                                 mitem: &MetaItem,
-                                 item: &Annotatable,
-                                 push: &mut dyn FnMut(Annotatable)) {
-    expand_deriving_encodable_imp(cx, span, mitem, item, push, "serialize")
-}
-
-fn expand_deriving_encodable_imp(cx: &mut ExtCtxt<'_>,
-                                 span: Span,
-                                 mitem: &MetaItem,
-                                 item: &Annotatable,
-                                 push: &mut dyn FnMut(Annotatable),
-                                 krate: &'static str) {
+    let krate = "rustc_serialize";
     let typaram = &*deriving::hygienic_type_parameter(item, "__S");
 
     let trait_def = TraitDef {
diff --git a/src/libsyntax_ext/lib.rs b/src/libsyntax_ext/lib.rs
index da11f2ff23f..0f3f5c0cd0e 100644
--- a/src/libsyntax_ext/lib.rs
+++ b/src/libsyntax_ext/lib.rs
@@ -92,9 +92,7 @@ pub fn register_builtin_macros(resolver: &mut dyn syntax::ext::base::Resolver, e
         Clone: clone::expand_deriving_clone,
         Copy: bounds::expand_deriving_copy,
         Debug: debug::expand_deriving_debug,
-        Decodable: decodable::expand_deriving_decodable,
         Default: default::expand_deriving_default,
-        Encodable: encodable::expand_deriving_encodable,
         Eq: eq::expand_deriving_eq,
         Hash: hash::expand_deriving_hash,
         Ord: ord::expand_deriving_ord,