consider glob imports in cfg suggestion

Author: bvanjoi

compiler/rustc_expand/src/expand.rs

@@ -1319,10 +1319,10 @@ impl InvocationCollectorNode for P<ast::Item> {
 
             let mut idents = Vec::new();
             collect_use_tree_leaves(ut, &mut idents);
-            return idents;
+            idents
+        } else {
+            self.kind.ident().into_iter().collect()
         }
-
-        if let Some(ident) = self.kind.ident() { vec![ident] } else { vec![] }
     }
 }
 

compiler/rustc_resolve/src/diagnostics.rs

@@ -6,7 +6,7 @@ use rustc_ast::{
 };
 use rustc_ast_pretty::pprust;
 use rustc_attr_data_structures::{self as attr, Stability};
-use rustc_data_structures::fx::FxHashSet;
+use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::unord::UnordSet;
 use rustc_errors::codes::*;
 use rustc_errors::{
@@ -2623,7 +2623,50 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         };
 
         for &StrippedCfgItem { parent_module, ident, ref cfg } in symbols {
-            if parent_module != module || ident.name != *segment {
+            if ident.name != *segment {
+                continue;
+            }
+
+            fn comes_from_same_module_for_glob(
+                r: &Resolver<'_, '_>,
+                parent_module: DefId,
+                module: DefId,
+                visited: &mut FxHashMap<DefId, bool>,
+            ) -> bool {
+                if let Some(&cached) = visited.get(&parent_module) {
+                    return cached;
+                }
+                visited.insert(parent_module, false);
+                let res = r.module_map.get(&parent_module).is_some_and(|m| {
+                    for importer in m.glob_importers.borrow().iter() {
+                        if let Some(next_parent_module) = importer.parent_scope.module.opt_def_id()
+                        {
+                            if next_parent_module == module
+                                || comes_from_same_module_for_glob(
+                                    r,
+                                    next_parent_module,
+                                    module,
+                                    visited,
+                                )
+                            {
+                                return true;
+                            }
+                        }
+                    }
+                    false
+                });
+                visited.insert(parent_module, res);
+                res
+            }
+
+            let comes_from_same_module = parent_module == module
+                || comes_from_same_module_for_glob(
+                    self,
+                    parent_module,
+                    module,
+                    &mut Default::default(),
+                );
+            if !comes_from_same_module {
                 continue;
             }
 

tests/ui/cfg/diagnostics-reexport-2.rs

@@ -0,0 +1,51 @@
+// issue#141256
+
+mod original {
+    #[cfg(false)]
+    //~^ NOTE the item is gated here
+    //~| NOTE the item is gated here
+    //~| NOTE the item is gated here
+    //~| NOTE the item is gated here
+    pub mod gated {
+    //~^ NOTE found an item that was configured out
+    //~| NOTE found an item that was configured out
+    //~| NOTE found an item that was configured out
+    //~| NOTE found an item that was configured out
+        pub fn foo() {}
+    }
+}
+
+mod reexport {
+    pub use super::original::*;
+}
+
+mod reexport2 {
+    pub use super::reexport::*;
+}
+
+mod reexport30 {
+    pub use super::original::*;
+    pub use super::reexport31::*;
+}
+
+mod reexport31 {
+    pub use super::reexport30::*;
+}
+
+fn main() {
+    reexport::gated::foo();
+    //~^ ERROR failed to resolve: could not find `gated` in `reexport`
+    //~| NOTE  could not find `gated` in `reexport`
+
+    reexport2::gated::foo();
+    //~^ ERROR failed to resolve: could not find `gated` in `reexport2`
+    //~| NOTE  could not find `gated` in `reexport2`
+
+    reexport30::gated::foo();
+    //~^ ERROR failed to resolve: could not find `gated` in `reexport30`
+    //~| NOTE  could not find `gated` in `reexport30`
+
+    reexport31::gated::foo();
+    //~^ ERROR failed to resolve: could not find `gated` in `reexport31`
+    //~| NOTE  could not find `gated` in `reexport31`
+}

tests/ui/cfg/diagnostics-reexport-2.stderr

@@ -0,0 +1,71 @@
+error[E0433]: failed to resolve: could not find `gated` in `reexport`
+  --> $DIR/diagnostics-reexport-2.rs:36:15
+   |
+LL |     reexport::gated::foo();
+   |               ^^^^^ could not find `gated` in `reexport`
+   |
+note: found an item that was configured out
+  --> $DIR/diagnostics-reexport-2.rs:9:13
+   |
+LL |     pub mod gated {
+   |             ^^^^^
+note: the item is gated here
+  --> $DIR/diagnostics-reexport-2.rs:4:5
+   |
+LL |     #[cfg(false)]
+   |     ^^^^^^^^^^^^^
+
+error[E0433]: failed to resolve: could not find `gated` in `reexport2`
+  --> $DIR/diagnostics-reexport-2.rs:40:16
+   |
+LL |     reexport2::gated::foo();
+   |                ^^^^^ could not find `gated` in `reexport2`
+   |
+note: found an item that was configured out
+  --> $DIR/diagnostics-reexport-2.rs:9:13
+   |
+LL |     pub mod gated {
+   |             ^^^^^
+note: the item is gated here
+  --> $DIR/diagnostics-reexport-2.rs:4:5
+   |
+LL |     #[cfg(false)]
+   |     ^^^^^^^^^^^^^
+
+error[E0433]: failed to resolve: could not find `gated` in `reexport30`
+  --> $DIR/diagnostics-reexport-2.rs:44:17
+   |
+LL |     reexport30::gated::foo();
+   |                 ^^^^^ could not find `gated` in `reexport30`
+   |
+note: found an item that was configured out
+  --> $DIR/diagnostics-reexport-2.rs:9:13
+   |
+LL |     pub mod gated {
+   |             ^^^^^
+note: the item is gated here
+  --> $DIR/diagnostics-reexport-2.rs:4:5
+   |
+LL |     #[cfg(false)]
+   |     ^^^^^^^^^^^^^
+
+error[E0433]: failed to resolve: could not find `gated` in `reexport31`
+  --> $DIR/diagnostics-reexport-2.rs:48:17
+   |
+LL |     reexport31::gated::foo();
+   |                 ^^^^^ could not find `gated` in `reexport31`
+   |
+note: found an item that was configured out
+  --> $DIR/diagnostics-reexport-2.rs:9:13
+   |
+LL |     pub mod gated {
+   |             ^^^^^
+note: the item is gated here
+  --> $DIR/diagnostics-reexport-2.rs:4:5
+   |
+LL |     #[cfg(false)]
+   |     ^^^^^^^^^^^^^
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0433`.