Auto merge of #53459 - petrochenkov:stabmore, r=nrc

Stabilize a few secondary macro features

- `tool_attributes` - closes https://github.com/rust-lang/rust/issues/44690
- `proc_macro_path_invoc` - this feature was created due to issues with tool attributes (https://github.com/rust-lang/rust/issues/51277), those issues are now fixed (https://github.com/rust-lang/rust/pull/52841)
- partially `proc_macro_gen` - this feature was created due to issue https://github.com/rust-lang/rust/issues/50504, the issue is now fixed (https://github.com/rust-lang/rust/pull/51952), so proc macros can generate modules. They still can't generate `macro_rules` items though due to unclear hygiene interactions.

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

-# `tool_attributes`
-
-The tracking issue for this feature is: [#44690]
-
-[#44690]: https://github.com/rust-lang/rust/issues/44690
-
-------------------------
-
-Tool attributes let you use scoped attributes to control the behavior
-of certain tools.
-
-Currently tool names which can be appear in scoped attributes are restricted to
-`clippy` and `rustfmt`.
-
-## An example
-
-```rust
-#![feature(tool_attributes)]
-
-#[rustfmt::skip]
-fn foo() { println!("hello, world"); }
-
-fn main() {
-    foo();
-}
-```

src/librustc_resolve/macros.rs

@@ -368,17 +368,6 @@ fn resolve_macro_to_def(&mut self, path: &ast::Path, kind: MacroKind, scope: Mar
 
         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);
@@ -391,10 +380,6 @@ fn resolve_macro_to_def(&mut self, path: &ast::Path, kind: MacroKind, scope: Mar
             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/libsyntax/ext/expand.rs

@@ -666,30 +666,25 @@ fn gate_proc_macro_expansion(&self, span: Span, fragment: &Option<AstFragment>)
             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/feature_gate.rs

@@ -441,9 +441,6 @@ pub fn walk_feature_fields<F>(&self, mut f: F)
     (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),
@@ -457,8 +454,6 @@ pub fn walk_feature_fields<F>(&self, mut f: F)
     // 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),
 
@@ -655,6 +650,10 @@ pub fn walk_feature_fields<F>(&self, mut f: F)
     (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/test/compile-fail-fulldeps/proc-macro/auxiliary/more-gates.rs

@@ -16,11 +16,6 @@
 
 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/more-gates.rs

@@ -14,9 +14,6 @@
 
 use foo::*;
 
-#[attr2mod]
-//~^ ERROR: cannot expand to modules
-pub fn a() {}
 #[attr2mac1]
 //~^ ERROR: cannot expand to macro definitions
 pub fn a() {}
@@ -24,12 +21,10 @@ pub fn a() {}
 //~^ 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/proc-macro-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 @@
 
 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/run-pass-fulldeps/proc-macro/derive-b.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/issue-42708.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-50061.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;
 

src/test/run-pass/tool_attributes.rs

@@ -10,7 +10,6 @@
 
 // Scoped attributes should not trigger an unused attributes lint.
 
-#![feature(tool_attributes)]
 #![deny(unused_attributes)]
 
 fn main() {

src/test/ui-fulldeps/proc-macro/generate-mod.rs

@@ -12,8 +12,6 @@
 
 // aux-build:generate-mod.rs
 
-#![feature(proc_macro_gen, proc_macro_path_invoc)]
-
 extern crate generate_mod;
 
 struct FromOutside;

src/test/ui-fulldeps/proc-macro/generate-mod.stderr

 error[E0412]: cannot find type `FromOutside` in this scope
-  --> $DIR/generate-mod.rs:21:1
+  --> $DIR/generate-mod.rs:19:1
    |
 LL | generate_mod::check!(); //~ ERROR cannot find type `FromOutside` in this scope
    | ^^^^^^^^^^^^^^^^^^^^^^^ not found in this scope
 
 error[E0412]: cannot find type `Outer` in this scope
-  --> $DIR/generate-mod.rs:21:1
+  --> $DIR/generate-mod.rs:19:1
    |
 LL | generate_mod::check!(); //~ ERROR cannot find type `FromOutside` in this scope
    | ^^^^^^^^^^^^^^^^^^^^^^^ not found in this scope
 
 error[E0412]: cannot find type `FromOutside` in this scope
-  --> $DIR/generate-mod.rs:24:1
+  --> $DIR/generate-mod.rs:22:1
    |
 LL | #[generate_mod::check_attr] //~ ERROR cannot find type `FromOutside` in this scope
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ not found in this scope
 
 error[E0412]: cannot find type `OuterAttr` in this scope
-  --> $DIR/generate-mod.rs:24:1
+  --> $DIR/generate-mod.rs:22:1
    |
 LL | #[generate_mod::check_attr] //~ ERROR cannot find type `FromOutside` in this scope
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ not found in this scope
 
 warning: cannot find type `FromOutside` in this scope
-  --> $DIR/generate-mod.rs:28:10
+  --> $DIR/generate-mod.rs:26:10
    |
 LL | #[derive(generate_mod::CheckDerive)] //~ WARN cannot find type `FromOutside` in this scope
    |          ^^^^^^^^^^^^^^^^^^^^^^^^^ names from parent modules are not accessible without an explicit import
@@ -33,7 +33,7 @@ LL | #[derive(generate_mod::CheckDerive)] //~ WARN cannot find type `FromOutside
    = note: for more information, see issue #50504 <https://github.com/rust-lang/rust/issues/50504>
 
 warning: cannot find type `OuterDerive` in this scope
-  --> $DIR/generate-mod.rs:28:10
+  --> $DIR/generate-mod.rs:26:10
    |
 LL | #[derive(generate_mod::CheckDerive)] //~ WARN cannot find type `FromOutside` in this scope
    |          ^^^^^^^^^^^^^^^^^^^^^^^^^ names from parent modules are not accessible without an explicit import
@@ -42,7 +42,7 @@ LL | #[derive(generate_mod::CheckDerive)] //~ WARN cannot find type `FromOutside
    = note: for more information, see issue #50504 <https://github.com/rust-lang/rust/issues/50504>
 
 warning: cannot find type `FromOutside` in this scope
-  --> $DIR/generate-mod.rs:35:14
+  --> $DIR/generate-mod.rs:33:14
    |
 LL |     #[derive(generate_mod::CheckDerive)] //~ WARN cannot find type `FromOutside` in this scope
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^ names from parent modules are not accessible without an explicit import
@@ -51,7 +51,7 @@ LL |     #[derive(generate_mod::CheckDerive)] //~ WARN cannot find type `FromOut
    = note: for more information, see issue #50504 <https://github.com/rust-lang/rust/issues/50504>
 
 warning: cannot find type `OuterDerive` in this scope
-  --> $DIR/generate-mod.rs:35:14
+  --> $DIR/generate-mod.rs:33:14
    |
 LL |     #[derive(generate_mod::CheckDerive)] //~ WARN cannot find type `FromOutside` in this scope
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^ names from parent modules are not accessible without an explicit import

src/test/ui/custom-attribute-multisegment.rs

@@ -10,7 +10,7 @@
 
 // Unresolved multi-segment attributes are not treated as custom.
 
-#![feature(custom_attribute, proc_macro_path_invoc)]
+#![feature(custom_attribute)]
 
 mod existent {}
 

src/test/ui/feature-gates/feature-gate-tool_attributes.rs

-// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-fn main() {
-    #[rustfmt::skip] //~ ERROR tool attributes are unstable
-    let x = 3
-        ;
-}

src/test/ui/feature-gates/feature-gate-tool_attributes.stderr

-error[E0658]: tool attributes are unstable (see issue #44690)
-  --> $DIR/feature-gate-tool_attributes.rs:12:7
-   |
-LL |     #[rustfmt::skip] //~ ERROR tool attributes are unstable
-   |       ^^^^^^^^^^^^^
-   |
-   = help: add #![feature(tool_attributes)] to the crate attributes to enable
-
-error: aborting due to previous error
-
-For more information about this error, try `rustc --explain E0658`.

src/test/ui/tool-attributes/tool-attributes-misplaced-1.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(tool_attributes, custom_attribute)]
+#![feature(custom_attribute)]
 
 type A = rustfmt; //~ ERROR expected type, found tool module `rustfmt`
 type B = rustfmt::skip; //~ ERROR expected type, found tool attribute `rustfmt::skip`

src/test/ui/tool-attributes/tool-attributes-misplaced-2.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(tool_attributes)]
-
 #[derive(rustfmt::skip)] //~ ERROR expected a macro, found tool attribute
 struct S;
 

src/test/ui/tool-attributes/tool-attributes-misplaced-2.stderr

 error: expected a macro, found tool attribute
-  --> $DIR/tool-attributes-misplaced-2.rs:13:10
+  --> $DIR/tool-attributes-misplaced-2.rs:11:10
    |
 LL | #[derive(rustfmt::skip)] //~ ERROR expected a macro, found tool attribute
    |          ^^^^^^^^^^^^^
 
 error: expected a macro, found tool attribute
-  --> $DIR/tool-attributes-misplaced-2.rs:17:5
+  --> $DIR/tool-attributes-misplaced-2.rs:15:5
    |
 LL |     rustfmt::skip!(); //~ ERROR expected a macro, found tool attribute
    |     ^^^^^^^^^^^^^

src/test/ui/tool-attributes/tool-attributes-shadowing.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(tool_attributes, proc_macro_path_invoc)]
-
 mod rustfmt {}
 
 #[rustfmt::skip] //~ ERROR failed to resolve. Could not find `skip` in `rustfmt`

src/test/ui/tool-attributes/tool-attributes-shadowing.stderr

 error[E0433]: failed to resolve. Could not find `skip` in `rustfmt`
-  --> $DIR/tool-attributes-shadowing.rs:15:12
+  --> $DIR/tool-attributes-shadowing.rs:13:12
    |
 LL | #[rustfmt::skip] //~ ERROR failed to resolve. Could not find `skip` in `rustfmt`
    |            ^^^^ Could not find `skip` in `rustfmt`

src/test/ui/unknown-tool-name.rs

@@ -8,7 +8,5 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(proc_macro_path_invoc)]
-
 #[foo::bar] //~ ERROR failed to resolve. Use of undeclared type or module `foo`
 fn main() {}

src/test/ui/unknown-tool-name.stderr

 error[E0433]: failed to resolve. Use of undeclared type or module `foo`
-  --> $DIR/unknown-tool-name.rs:13:3
+  --> $DIR/unknown-tool-name.rs:11:3
    |
 LL | #[foo::bar] //~ ERROR failed to resolve. Use of undeclared type or module `foo`
    |   ^^^ Use of undeclared type or module `foo`