Stabilize a few secondary macro features

`tool_attributes`, `proc_macro_path_invoc`, partially `proc_macro_gen`

Author: petrochenkov

src/doc/unstable-book/src/language-features/tool-attributes.md

@@ -367,17 +367,6 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
 
         let def = def?;
 
-        if path.segments.len() > 1 {
-            if kind != MacroKind::Bang {
-                if def != Def::NonMacroAttr(NonMacroAttrKind::Tool) &&
-                   !self.session.features_untracked().proc_macro_path_invoc {
-                    let msg = format!("non-ident {} paths are unstable", kind.descr());
-                    emit_feature_err(&self.session.parse_sess, "proc_macro_path_invoc",
-                                     path.span, GateIssue::Language, &msg);
-                }
-            }
-        }
-
         match def {
             Def::Macro(def_id, macro_kind) => {
                 self.unused_macros.remove(&def_id);
@@ -390,10 +379,6 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
             Def::NonMacroAttr(attr_kind) => {
                 if kind == MacroKind::Attr {
                     let features = self.session.features_untracked();
-                    if attr_kind == NonMacroAttrKind::Tool && !features.tool_attributes {
-                        feature_err(&self.session.parse_sess, "tool_attributes", path.span,
-                                    GateIssue::Language, "tool attributes are unstable").emit();
-                    }
                     if attr_kind == NonMacroAttrKind::Custom {
                         assert!(path.segments.len() == 1);
                         let name = path.segments[0].ident.name.as_str();

src/librustc_resolve/macros.rs

@@ -666,30 +666,25 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
             None => return,
         };
 
-        fragment.visit_with(&mut DisallowModules {
+        fragment.visit_with(&mut DisallowMacros {
             span,
             parse_sess: self.cx.parse_sess,
         });
 
-        struct DisallowModules<'a> {
+        struct DisallowMacros<'a> {
             span: Span,
             parse_sess: &'a ParseSess,
         }
 
-        impl<'ast, 'a> Visitor<'ast> for DisallowModules<'a> {
+        impl<'ast, 'a> Visitor<'ast> for DisallowMacros<'a> {
             fn visit_item(&mut self, i: &'ast ast::Item) {
-                let name = match i.node {
-                    ast::ItemKind::Mod(_) => Some("modules"),
-                    ast::ItemKind::MacroDef(_) => Some("macro definitions"),
-                    _ => None,
-                };
-                if let Some(name) = name {
+                if let ast::ItemKind::MacroDef(_) = i.node {
                     emit_feature_err(
                         self.parse_sess,
                         "proc_macro_gen",
                         self.span,
                         GateIssue::Language,
-                        &format!("procedural macros cannot expand to {}", name),
+                        &format!("procedural macros cannot expand to macro definitions"),
                     );
                 }
                 visit::walk_item(self, i);

src/libsyntax/ext/expand.rs

@@ -438,9 +438,6 @@ declare_features! (
     (active, tbm_target_feature, "1.27.0", Some(44839), None),
     (active, wasm_target_feature, "1.30.0", Some(44839), None),
 
-    // Allows macro invocations of the form `#[foo::bar]`
-    (active, proc_macro_path_invoc, "1.27.0", Some(38356), None),
-
     // Allows macro invocations on modules expressions and statements and
     // procedural macros to expand to non-items.
     (active, proc_macro_mod, "1.27.0", Some(38356), None),
@@ -454,8 +451,6 @@ declare_features! (
     // Access to crate names passed via `--extern` through prelude
     (active, extern_prelude, "1.27.0", Some(44660), Some(Edition::Edition2018)),
 
-    // Scoped attributes
-    (active, tool_attributes, "1.25.0", Some(44690), None),
     // Scoped lints
     (active, tool_lints, "1.28.0", Some(44690), None),
 
@@ -652,6 +647,10 @@ declare_features! (
     (accepted, use_extern_macros, "1.30.0", Some(35896), None),
     // Allows keywords to be escaped for use as identifiers
     (accepted, raw_identifiers, "1.30.0", Some(48589), None),
+    // Attributes scoped to tools
+    (accepted, tool_attributes, "1.30.0", Some(44690), None),
+    // Allows multi-segment paths in attributes and derives
+    (accepted, proc_macro_path_invoc, "1.30.0", Some(38356), None),
 );
 
 // If you change this, please modify src/doc/unstable-book as well. You must

src/libsyntax/feature_gate.rs

@@ -16,11 +16,6 @@ extern crate proc_macro;
 
 use proc_macro::*;
 
-#[proc_macro_attribute]
-pub fn attr2mod(_: TokenStream, _: TokenStream) -> TokenStream {
-    "mod test {}".parse().unwrap()
-}
-
 #[proc_macro_attribute]
 pub fn attr2mac1(_: TokenStream, _: TokenStream) -> TokenStream {
     "macro_rules! foo1 { (a) => (a) }".parse().unwrap()
@@ -31,11 +26,6 @@ pub fn attr2mac2(_: TokenStream, _: TokenStream) -> TokenStream {
     "macro foo2(a) { a }".parse().unwrap()
 }
 
-#[proc_macro]
-pub fn mac2mod(_: TokenStream) -> TokenStream {
-    "mod test2 {}".parse().unwrap()
-}
-
 #[proc_macro]
 pub fn mac2mac1(_: TokenStream) -> TokenStream {
     "macro_rules! foo3 { (a) => (a) }".parse().unwrap()
@@ -49,7 +39,6 @@ pub fn mac2mac2(_: TokenStream) -> TokenStream {
 #[proc_macro]
 pub fn tricky(_: TokenStream) -> TokenStream {
     "fn foo() {
-        mod test {}
         macro_rules! foo { (a) => (a) }
     }".parse().unwrap()
 }

src/test/compile-fail-fulldeps/proc-macro/auxiliary/more-gates.rs

@@ -14,22 +14,17 @@ extern crate more_gates as foo;
 
 use foo::*;
 
-#[attr2mod]
-//~^ ERROR: cannot expand to modules
-pub fn a() {}
 #[attr2mac1]
 //~^ ERROR: cannot expand to macro definitions
 pub fn a() {}
 #[attr2mac2]
 //~^ ERROR: cannot expand to macro definitions
 pub fn a() {}
 
-mac2mod!(); //~ ERROR: cannot expand to modules
 mac2mac1!(); //~ ERROR: cannot expand to macro definitions
 mac2mac2!(); //~ ERROR: cannot expand to macro definitions
 
 tricky!();
-//~^ ERROR: cannot expand to modules
-//~| ERROR: cannot expand to macro definitions
+//~^ ERROR: cannot expand to macro definitions
 
 fn main() {}

src/test/compile-fail-fulldeps/proc-macro/more-gates.rs

@@ -10,7 +10,6 @@
 
 // aux-build:proc-macro-gates.rs
 // gate-test-proc_macro_non_items
-// gate-test-proc_macro_path_invoc
 // gate-test-proc_macro_mod line
 // gate-test-proc_macro_expr
 // gate-test-proc_macro_mod
@@ -22,20 +21,15 @@ extern crate proc_macro_gates as foo;
 
 use foo::*;
 
-#[foo::a] //~ ERROR: non-ident attribute macro paths are unstable
-fn _test() {}
-
 fn _test_inner() {
     #![a] // OK
 }
 
 #[a] //~ ERROR: custom attributes cannot be applied to modules
-//~| ERROR: procedural macros cannot expand to modules
 mod _test2 {}
 
 mod _test2_inner {
     #![a] //~ ERROR: custom attributes cannot be applied to modules
-    //~| ERROR: procedural macros cannot expand to modules
 }
 
 #[a = y] //~ ERROR: must only be followed by a delimiter token

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

@@ -11,7 +11,7 @@
 // aux-build:derive-b.rs
 // ignore-stage1
 
-#![feature(proc_macro_path_invoc, unrestricted_attribute_tokens)]
+#![feature(unrestricted_attribute_tokens)]
 
 extern crate derive_b;
 

src/test/run-pass-fulldeps/proc-macro/derive-b.rs

@@ -11,7 +11,7 @@
 // aux-build:issue-42708.rs
 // ignore-stage1
 
-#![feature(decl_macro, proc_macro_path_invoc)]
+#![feature(decl_macro)]
 #![allow(unused)]
 
 extern crate issue_42708;

src/test/run-pass-fulldeps/proc-macro/issue-42708.rs

@@ -11,7 +11,7 @@
 // aux-build:issue-50061.rs
 // ignore-stage1
 
-#![feature(proc_macro_path_invoc, decl_macro)]
+#![feature(decl_macro)]
 
 extern crate issue_50061;