Stabilize #[my_macro] mod foo; (part of proc_macro_hygiene)

compiler/rustc_expand/src/expand.rs

@@ -5,7 +5,7 @@ use std::{iter, mem, slice};
 
 use rustc_ast::mut_visit::*;
 use rustc_ast::tokenstream::TokenStream;
-use rustc_ast::visit::{self, AssocCtxt, Visitor, VisitorResult, try_visit, walk_list};
+use rustc_ast::visit::{AssocCtxt, Visitor, VisitorResult, try_visit, walk_list};
 use rustc_ast::{
     self as ast, AssocItemKind, AstNodeWrapper, AttrArgs, AttrItemKind, AttrStyle, AttrVec,
     DUMMY_NODE_ID, DelegationSource, DelegationSuffixes, EarlyParsedAttribute, ExprKind,
@@ -20,7 +20,7 @@ use rustc_attr_parsing::{
 };
 use rustc_data_structures::flat_map_in_place::FlatMapInPlace;
 use rustc_data_structures::stack::ensure_sufficient_stack;
-use rustc_errors::{PResult, msg};
+use rustc_errors::PResult;
 use rustc_feature::Features;
 use rustc_hir::Target;
 use rustc_hir::def::MacroKinds;
@@ -29,7 +29,6 @@ use rustc_parse::parser::{
     AllowConstBlockItems, AttemptLocalParseRecovery, CommaRecoveryMode, ForceCollect, Parser,
     RecoverColon, RecoverComma, Recovery, token_descr,
 };
-use rustc_session::Session;
 use rustc_session::errors::feature_err;
 use rustc_session::lint::builtin::{UNUSED_ATTRIBUTES, UNUSED_DOC_COMMENTS};
 use rustc_span::hygiene::SyntaxContext;
@@ -770,7 +769,6 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
             }
             InvocationKind::Attr { attr, pos, mut item, derives } => {
                 if let Some(expander) = ext.as_attr() {
-                    self.gate_proc_macro_input(&item);
                     self.gate_proc_macro_attr_item(span, &item);
                     let tokens = match &item {
                         // FIXME: Collect tokens and use them instead of generating
@@ -904,9 +902,6 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
             InvocationKind::Derive { path, item, is_const } => match ext {
                 SyntaxExtensionKind::Derive(expander)
                 | SyntaxExtensionKind::LegacyDerive(expander) => {
-                    if let SyntaxExtensionKind::Derive(..) = ext {
-                        self.gate_proc_macro_input(&item);
-                    }
                     // The `MetaItem` representing the trait to derive can't
                     // have an unsafe around it (as of now).
                     let meta = ast::MetaItem {
@@ -1043,37 +1038,6 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
         .emit();
     }
 
-    fn gate_proc_macro_input(&self, annotatable: &Annotatable) {
-        struct GateProcMacroInput<'a> {
-            sess: &'a Session,
-        }
-
-        impl<'ast, 'a> Visitor<'ast> for GateProcMacroInput<'a> {
-            fn visit_item(&mut self, item: &'ast ast::Item) {
-                match &item.kind {
-                    ItemKind::Mod(_, _, mod_kind)
-                        if !matches!(mod_kind, ModKind::Loaded(_, Inline::Yes, _)) =>
-                    {
-                        feature_err(
-                            self.sess,
-                            sym::proc_macro_hygiene,
-                            item.span,
-                            msg!("file modules in proc macro input are unstable"),
-                        )
-                        .emit();
-                    }
-                    _ => {}
-                }
-
-                visit::walk_item(self, item);
-            }
-        }
-
-        if !self.cx.ecfg.features.proc_macro_hygiene() {
-            annotatable.visit_with(&mut GateProcMacroInput { sess: self.cx.sess });
-        }
-    }
-
     fn parse_ast_fragment(
         &mut self,
         toks: TokenStream,

compiler/rustc_feature/src/unstable.rs

@@ -688,7 +688,7 @@ declare_features! (
     (unstable, powerpc_target_feature, "1.27.0", Some(150255)),
     /// The prfchw target feature on x86.
     (unstable, prfchw_target_feature, "1.78.0", Some(150256)),
-    /// Allows macro attributes on expressions, statements and non-inline modules.
+    /// Allows macro attributes on expressions and statements.
     (unstable, proc_macro_hygiene, "1.30.0", Some(54727)),
     /// Allows the use of raw-dylibs on ELF platforms
     (incomplete, raw_dylib_elf, "1.87.0", Some(135694)),

tests/ui/proc-macro/attributes-on-modules-fail.rs

@@ -17,31 +17,4 @@ type A = X; //~ ERROR cannot find type `X` in this scope
 #[derive(Copy)] //~ ERROR `derive` may only be applied to `struct`s, `enum`s and `union`s
 mod n {}
 
-#[empty_attr]
-mod module; //~ ERROR file modules in proc macro input are unstable
-
-#[empty_attr]
-mod outer {
-    mod inner; //~ ERROR file modules in proc macro input are unstable
-
-    mod inner_inline {} // OK
-}
-
-#[derive(Empty)]
-struct S {
-    field: [u8; {
-        #[path = "outer/inner.rs"]
-        mod inner; //~ ERROR file modules in proc macro input are unstable
-        mod inner_inline {} // OK
-        0
-    }],
-}
-
-#[identity_attr]
-fn f() {
-    #[path = "outer/inner.rs"]
-    mod inner; //~ ERROR file modules in proc macro input are unstable
-    mod inner_inline {} // OK
-}
-
 fn main() {}

tests/ui/proc-macro/attributes-on-modules-fail.stderr

@@ -6,46 +6,6 @@ LL | #[derive(Copy)]
 LL | mod n {}
    | -------- not a `struct`, `enum` or `union`
 
-error[E0658]: file modules in proc macro input are unstable
-  --> $DIR/attributes-on-modules-fail.rs:21:1
-   |
-LL | mod module;
-   | ^^^^^^^^^^^
-   |
-   = note: see issue #54727 <https://github.com/rust-lang/rust/issues/54727> for more information
-   = help: add `#![feature(proc_macro_hygiene)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-
-error[E0658]: file modules in proc macro input are unstable
-  --> $DIR/attributes-on-modules-fail.rs:25:5
-   |
-LL |     mod inner;
-   |     ^^^^^^^^^^
-   |
-   = note: see issue #54727 <https://github.com/rust-lang/rust/issues/54727> for more information
-   = help: add `#![feature(proc_macro_hygiene)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-
-error[E0658]: file modules in proc macro input are unstable
-  --> $DIR/attributes-on-modules-fail.rs:34:9
-   |
-LL |         mod inner;
-   |         ^^^^^^^^^^
-   |
-   = note: see issue #54727 <https://github.com/rust-lang/rust/issues/54727> for more information
-   = help: add `#![feature(proc_macro_hygiene)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-
-error[E0658]: file modules in proc macro input are unstable
-  --> $DIR/attributes-on-modules-fail.rs:43:5
-   |
-LL |     mod inner;
-   |     ^^^^^^^^^^
-   |
-   = note: see issue #54727 <https://github.com/rust-lang/rust/issues/54727> for more information
-   = help: add `#![feature(proc_macro_hygiene)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-
 error[E0425]: cannot find type `Y` in this scope
   --> $DIR/attributes-on-modules-fail.rs:11:14
    |
@@ -68,7 +28,7 @@ help: consider importing this struct
 LL + use m::X;
    |
 
-error: aborting due to 7 previous errors
+error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0425, E0658, E0774.
+Some errors have detailed explanations: E0425, E0774.
 For more information about an error, try `rustc --explain E0425`.

tests/ui/proc-macro/auxiliary/expect-modules.rs

@@ -0,0 +1,41 @@
+/// Macros that assert that certain `mod` items are present in their input.
+
+extern crate proc_macro;
+
+use proc_macro::TokenStream;
+
+#[proc_macro_attribute]
+pub fn expect_mod_item(_attrs: TokenStream, item: TokenStream) -> TokenStream {
+    let s = item.to_string();
+
+    assert_eq!(s, "mod module;");
+
+    item
+}
+
+#[proc_macro_attribute]
+pub fn expect_mods_attr(_attrs: TokenStream, item: TokenStream) -> TokenStream {
+    let s = item.to_string();
+
+    assert_contains(&s, "mod attr_outlined;");
+    assert_contains(&s, "mod attr_inline {}");
+
+    item
+}
+
+#[proc_macro_derive(ExpectModsDerive)]
+pub fn expect_mods_derive(item: TokenStream) -> TokenStream {
+    let s = item.to_string();
+
+    assert_contains(&s, "mod derive_outlined;");
+    assert_contains(&s, "mod derive_inline {}");
+
+    TokenStream::new()
+}
+
+#[track_caller]
+fn assert_contains(s: &str, needle: &str) {
+    if !s.contains(needle) {
+        panic!("{needle:?} not found in:\n---\n{s}\n---\n");
+    }
+}

tests/ui/proc-macro/inner-attr-file-mod.rs

@@ -9,8 +9,7 @@ extern crate test_macros;
 
 #[deny(unused_attributes)]
 mod module_with_attrs;
-//~^ ERROR file modules in proc macro input are unstable
-//~| ERROR custom inner attributes are unstable
+//~^ ERROR custom inner attributes are unstable
 
 fn main() {}
 

tests/ui/proc-macro/inner-attr-file-mod.stderr

@@ -18,16 +18,6 @@ LL | #![print_attr]
    = help: add `#![feature(custom_inner_attributes)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
-error[E0658]: file modules in proc macro input are unstable
-  --> $DIR/inner-attr-file-mod.rs:11:1
-   |
-LL | mod module_with_attrs;
-   | ^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #54727 <https://github.com/rust-lang/rust/issues/54727> for more information
-   = help: add `#![feature(proc_macro_hygiene)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-
 error[E0658]: custom inner attributes are unstable
   --> $DIR/inner-attr-file-mod.rs:11:1
    |
@@ -38,6 +28,6 @@ LL | mod module_with_attrs;
    = help: add `#![feature(custom_inner_attributes)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
-error: aborting due to 4 previous errors
+error: aborting due to 3 previous errors
 
 For more information about this error, try `rustc --explain E0658`.

tests/ui/proc-macro/module.rs

@@ -1 +1,4 @@
-//@ ignore-auxiliary (used by `./attributes-on-modules-fail.rs`)
+//@ ignore-auxiliary (used by `./attributes-on-modules-fail.rs` and `modules-in-input.rs`)
+
+// An item that can be referenced to verify the module has been properly loaded.
+pub const fn hello() {}

tests/ui/proc-macro/modules-in-input.rs

@@ -0,0 +1,47 @@
+//@ check-pass
+//@ proc-macro: expect-modules.rs
+//@ reference: macro.invocation.attr.mod
+
+// Verifies how module items are represented in proc macro input.
+
+#[macro_use]
+extern crate expect_modules;
+
+#[expect_modules::expect_mod_item]
+mod module;
+
+fn check() {
+    module::hello();
+}
+
+#[expect_modules::expect_mods_attr]
+mod outer {
+    #[path = "../module.rs"]
+    mod attr_outlined;
+    mod attr_inline {}
+
+    fn check() {
+        attr_outlined::hello();
+    }
+}
+
+#[expect_modules::expect_mods_attr]
+fn foo() {
+    #[path = "module.rs"]
+    mod attr_outlined;
+    mod attr_inline {}
+    attr_outlined::hello();
+}
+
+#[derive(expect_modules::ExpectModsDerive)]
+struct Foo(
+    [u8; {
+        #[path = "module.rs"]
+        mod derive_outlined;
+        mod derive_inline {}
+        derive_outlined::hello();
+        0
+    }],
+);
+
+fn main() {}

tests/ui/proc-macro/unsafe-mod.rs

@@ -1,8 +1,6 @@
 //@ run-pass
 //@ proc-macro: macro-only-syntax.rs
 
-#![feature(proc_macro_hygiene)]
-
 extern crate macro_only_syntax;
 
 #[macro_only_syntax::expect_unsafe_mod]