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

Author: alexcrichton

src/libproc_macro/lib.rs

@@ -15,8 +15,7 @@
 //! Currently the primary use of this crate is to provide the ability to define
 //! new custom derive modes through `#[proc_macro_derive]`.
 //!
-//! Added recently as part of [RFC 1681] this crate is currently *unstable* and
-//! requires the `#![feature(proc_macro_lib)]` directive to use.
+//! Added recently as part of [RFC 1681] this crate is stable as of Rust 1.15.0.
 //!
 //! [RFC 1681]: https://github.com/rust-lang/rfcs/blob/master/text/1681-macros-1.1.md
 //!
@@ -27,7 +26,7 @@
 //! area for macro authors is stabilized.
 
 #![crate_name = "proc_macro"]
-#![unstable(feature = "proc_macro_lib", issue = "27812")]
+#![stable(feature = "proc_macro_lib", since = "1.15.0")]
 #![crate_type = "rlib"]
 #![crate_type = "dylib"]
 #![cfg_attr(not(stage0), deny(warnings))]
@@ -55,12 +54,14 @@ use syntax::ptr::P;
 ///
 /// The API of this type is intentionally bare-bones, but it'll be expanded over
 /// time!
+#[stable(feature = "proc_macro_lib", since = "1.15.0")]
 pub struct TokenStream {
     inner: Vec<P<ast::Item>>,
 }
 
 /// Error returned from `TokenStream::from_str`.
 #[derive(Debug)]
+#[stable(feature = "proc_macro_lib", since = "1.15.0")]
 pub struct LexError {
     _inner: (),
 }
@@ -131,6 +132,7 @@ pub mod __internal {
     }
 }
 
+#[stable(feature = "proc_macro_lib", since = "1.15.0")]
 impl FromStr for TokenStream {
     type Err = LexError;
 
@@ -154,6 +156,7 @@ impl FromStr for TokenStream {
     }
 }
 
+#[stable(feature = "proc_macro_lib", since = "1.15.0")]
 impl fmt::Display for TokenStream {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         for item in self.inner.iter() {

src/librustc_driver/driver.rs

@@ -714,8 +714,7 @@ pub fn phase_2_configure_and_expand<F>(sess: &Session,
                                                      is_proc_macro_crate,
                                                      is_test_crate,
                                                      num_crate_types,
-                                                     sess.diagnostic(),
-                                                     &sess.features.borrow())
+                                                     sess.diagnostic())
         });
     }
 

src/librustc_metadata/lib.rs

@@ -21,7 +21,6 @@
 #![feature(conservative_impl_trait)]
 #![feature(core_intrinsics)]
 #![feature(proc_macro_internals)]
-#![feature(proc_macro_lib)]
 #![feature(quote)]
 #![feature(rustc_diagnostic_macros)]
 #![feature(rustc_private)]

src/libsyntax/ext/expand.rs

@@ -923,7 +923,6 @@ impl<'feat> ExpansionConfig<'feat> {
         fn enable_allow_internal_unstable = allow_internal_unstable,
         fn enable_custom_derive = custom_derive,
         fn enable_pushpop_unsafe = pushpop_unsafe,
-        fn enable_proc_macro = proc_macro,
     }
 }
 

src/libsyntax/feature_gate.rs

@@ -279,9 +279,6 @@ declare_features! (
     // instead of just the platforms on which it is the C ABI
     (active, abi_sysv64, "1.13.0", Some(36167)),
 
-    // Macros 1.1
-    (active, proc_macro, "1.13.0", Some(35900)),
-
     // Allows untagged unions `union U { ... }`
     (active, untagged_unions, "1.13.0", Some(32836)),
 
@@ -364,6 +361,8 @@ declare_features! (
     // Allows `..` in tuple (struct) patterns
     (accepted, dotdot_in_tuple_patterns, "1.14.0", Some(33627)),
     (accepted, item_like_imports, "1.14.0", Some(35120)),
+    // Macros 1.1
+    (accepted, proc_macro, "1.15.0", Some(35900)),
 );
 // (changing above list without updating src/doc/reference.md makes @cmr sad)
 
@@ -637,11 +636,7 @@ pub const BUILTIN_ATTRIBUTES: &'static [(&'static str, AttributeType, AttributeG
                                         is an experimental feature",
                                        cfg_fn!(fundamental))),
 
-    ("proc_macro_derive", Normal, Gated(Stability::Unstable,
-                                        "proc_macro",
-                                        "the `#[proc_macro_derive]` attribute \
-                                         is an experimental feature",
-                                        cfg_fn!(proc_macro))),
+    ("proc_macro_derive", Normal, Ungated),
 
     ("rustc_copy_clone_marker", Whitelisted, Gated(Stability::Unstable,
                                                    "rustc_attrs",
@@ -747,7 +742,6 @@ const GATED_CFGS: &'static [(&'static str, &'static str, fn(&Features) -> bool)]
     ("target_vendor", "cfg_target_vendor", cfg_fn!(cfg_target_vendor)),
     ("target_thread_local", "cfg_target_thread_local", cfg_fn!(cfg_target_thread_local)),
     ("target_has_atomic", "cfg_target_has_atomic", cfg_fn!(cfg_target_has_atomic)),
-    ("proc_macro", "proc_macro", cfg_fn!(proc_macro)),
 ];
 
 #[derive(Debug, Eq, PartialEq)]

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;
@@ -218,12 +218,6 @@ 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();

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)]

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 {

src/test/compile-fail-fulldeps/proc-macro/attribute.rs

@@ -9,7 +9,6 @@
 // except according to those terms.
 
 #![crate_type = "proc-macro"]
-#![feature(proc_macro, proc_macro_lib)]
 
 extern crate proc_macro;
 

src/test/compile-fail-fulldeps/proc-macro/auxiliary/derive-a-b.rs

@@ -11,7 +11,6 @@
 // force-host
 // no-prefer-dynamic
 
-#![feature(proc_macro, proc_macro_lib)]
 #![crate_type = "proc-macro"]
 
 extern crate proc_macro;