Add feature to set path-based visibility of macro_rules to pub by default

Author: yaahc

compiler/rustc_feature/src/unstable.rs

@@ -568,6 +568,8 @@ declare_features! (
     (unstable, macro_attr, "1.91.0", Some(143547)),
     /// Allow `macro_rules!` derive rules
     (unstable, macro_derive, "1.91.0", Some(143549)),
+    /// Make `macro_rules!` implicitly pub even without `macro_export`
+    (unstable, macro_implicit_pub, "1.94.0", Some(148610)),
     /// Give access to additional metadata about declarative macro meta-variables.
     (unstable, macro_metavar_expr, "1.61.0", Some(83527)),
     /// Provides a way to concatenate identifiers using metavariable expressions.

compiler/rustc_lint/src/builtin.rs

@@ -1288,6 +1288,11 @@ impl<'tcx> LateLintPass<'tcx> for UnreachablePub {
         if let hir::ItemKind::Use(_, hir::UseKind::ListStem) = &item.kind {
             return;
         }
+        // Do not warn for macro_rules definitions which are pub and unreachable by default,
+        // only check their associated use re-exports.
+        if let hir::ItemKind::Macro(_, ast::MacroDef { macro_rules: true, .. }, _) = &item.kind {
+            return;
+        }
         self.perform_lint(cx, "item", item.owner_id.def_id, item.vis_span, true);
     }
 

compiler/rustc_resolve/src/build_reduced_graph.rs

@@ -1299,7 +1299,7 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
             let ident = ident.normalize_to_macros_2_0();
             self.r.macro_names.insert(ident);
             let is_macro_export = ast::attr::contains_name(&item.attrs, sym::macro_export);
-            let vis = if is_macro_export {
+            let vis = if is_macro_export || self.r.tcx().features().macro_implicit_pub() {
                 Visibility::Public
             } else {
                 Visibility::Restricted(CRATE_DEF_ID)

compiler/rustc_span/src/symbol.rs

@@ -1380,6 +1380,7 @@ symbols! {
         macro_derive,
         macro_escape,
         macro_export,
+        macro_implicit_pub,
         macro_lifetime_matcher,
         macro_literal_matcher,
         macro_metavar_expr,

tests/ui/macros/auxiliary/implicit-pub.rs

@@ -1,11 +1,11 @@
 //@ edition:2018
+#![feature(macro_implicit_pub)]
 pub mod inner {
     #[allow(unused_macros)]
     macro_rules! fake_pub {
         () => {}
     }
 
-    #[macro_export]
     macro_rules! real_pub {
         () => {}
     }

tests/ui/macros/implicit-pub-still-unreachable.rs

@@ -1,5 +1,6 @@
 //@ aux-build:implicit-pub.rs
 //@ edition:2018
+#![feature(macro_implicit_pub)]
 
 extern crate implicit_pub;
 

tests/ui/macros/implicit-pub-still-unreachable.stderr

@@ -1,5 +1,5 @@
 error[E0433]: failed to resolve: could not find `fake_pub` in `inner`
-  --> $DIR/implicit-pub-still-unreachable.rs:7:26
+  --> $DIR/implicit-pub-still-unreachable.rs:8:26
    |
 LL |     implicit_pub::inner::fake_pub!();
    |                          ^^^^^^^^ could not find `fake_pub` in `inner`

tests/ui/macros/implicit-pub-unreachable-lint.rs

@@ -1,8 +1,8 @@
 //@ edition:2018
 #![crate_type = "lib"]
+#![feature(macro_implicit_pub)]
 #![deny(unreachable_pub)]
 
-#[macro_export]
 macro_rules! not_reexported {
     () => {}
 }

tests/ui/macros/implicit-pub-unreachable-lint.stderr

@@ -8,7 +8,7 @@ LL |     pub use not_reexported;
    |
    = help: or consider exporting it for use by other crates
 note: the lint level is defined here
-  --> $DIR/implicit-pub-unreachable-lint.rs:3:9
+  --> $DIR/implicit-pub-unreachable-lint.rs:4:9
    |
 LL | #![deny(unreachable_pub)]
    |         ^^^^^^^^^^^^^^^

tests/ui/macros/implicit-pub.rs

@@ -1,6 +1,7 @@
 //@ check-pass
 //@ aux-build:implicit-pub.rs
 //@ edition:2018
+#![feature(macro_implicit_pub)]
 
 extern crate implicit_pub;