rustc: Stabilize the `proc_macro` feature

This commit stabilizes the `proc_macro` and `proc_macro_lib` features in the
compiler to stabilize the "Macros 1.1" feature of the language. Many more
details can be found on the tracking issue, #35900.

Closes #35900

1 files changed, 1 insertions, 7 deletions

diff --git a/src/libsyntax_ext/deriving/mod.rs b/src/libsyntax_ext/deriving/mod.rs
index 0511b0d252b..2573690d153 100644
--- a/src/libsyntax_ext/deriving/mod.rs
+++ b/src/libsyntax_ext/deriving/mod.rs
@@ -15,7 +15,7 @@ use syntax::attr::HasAttrs;
 use syntax::codemap;
 use syntax::ext::base::{Annotatable, ExtCtxt, SyntaxExtension};
 use syntax::ext::build::AstBuilder;
-use syntax::feature_gate::{self, emit_feature_err};
+use syntax::feature_gate;
 use syntax::ptr::P;
 use syntax::symbol::Symbol;
 use syntax_pos::Span;
@@ -220,12 +220,6 @@ pub fn expand_derive(cx: &mut ExtCtxt,
                                  .filter(|&(_, ref name)| !is_builtin_trait(name.name().unwrap()))
                                  .next();
     if let Some((i, titem)) = macros_11_derive {
-        if !cx.ecfg.features.unwrap().proc_macro {
-            let issue = feature_gate::GateIssue::Language;
-            let msg = "custom derive macros are experimentally supported";
-            emit_feature_err(cx.parse_sess, "proc_macro", titem.span, issue, msg);
-        }
-
         let tname = ast::Ident::with_empty_ctxt(titem.name().unwrap());
         let path = ast::Path::from_ident(titem.span, tname);
         let ext = cx.resolver.resolve_macro(cx.current_expansion.mark, &path, false).unwrap();