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

3 files changed, 2 insertions, 17 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();
diff --git a/src/libsyntax_ext/lib.rs b/src/libsyntax_ext/lib.rs
index e31b29d5cc1..cbc2b2263f2 100644
--- a/src/libsyntax_ext/lib.rs
+++ b/src/libsyntax_ext/lib.rs
@@ -19,7 +19,6 @@
        html_root_url = "https://doc.rust-lang.org/nightly/")]
 #![cfg_attr(not(stage0), deny(warnings))]
 
-#![feature(proc_macro_lib)]
 #![feature(proc_macro_internals)]
 #![feature(rustc_private)]
 #![feature(staged_api)]
diff --git a/src/libsyntax_ext/proc_macro_registrar.rs b/src/libsyntax_ext/proc_macro_registrar.rs
index 5323ace79d8..c93e2c054d2 100644
--- a/src/libsyntax_ext/proc_macro_registrar.rs
+++ b/src/libsyntax_ext/proc_macro_registrar.rs
@@ -17,7 +17,6 @@ use syntax::ext::base::ExtCtxt;
 use syntax::ext::build::AstBuilder;
 use syntax::ext::expand::ExpansionConfig;
 use syntax::parse::ParseSess;
-use syntax::feature_gate::Features;
 use syntax::fold::Folder;
 use syntax::ptr::P;
 use syntax::symbol::Symbol;
@@ -47,8 +46,7 @@ pub fn modify(sess: &ParseSess,
               is_proc_macro_crate: bool,
               is_test_crate: bool,
               num_crate_types: usize,
-              handler: &errors::Handler,
-              features: &Features) -> ast::Crate {
+              handler: &errors::Handler) -> ast::Crate {
     let ecfg = ExpansionConfig::default("proc_macro".to_string());
     let mut cx = ExtCtxt::new(sess, ecfg, resolver);
 
@@ -66,12 +64,6 @@ pub fn modify(sess: &ParseSess,
 
     if !is_proc_macro_crate {
         return krate
-    } else if !features.proc_macro {
-        let mut err = handler.struct_err("the `proc-macro` crate type is \
-                                          experimental");
-        err.help("add #![feature(proc_macro)] to the crate attributes to \
-                  enable");
-        err.emit();
     }
 
     if num_crate_types > 1 {