Expand name resolution stub

Author: yaahc

src/items/use-declarations.md

@@ -116,6 +116,7 @@ They may create bindings for:
 * [Built-in types]
 * [Attributes]
 * [Derive macros]
+* [`macro_rules`]
 
 r[items.use.path.disallowed]
 They cannot import [associated items], [generic parameters], [local variables], paths with [`Self`], or [tool attributes]. More restrictions are described below.
@@ -389,58 +390,9 @@ r[items.use.restrictions.variant]
   use TypeAlias::MyVariant; //~ ERROR
   ```
 
-r[items.use.ambiguities]
-## Ambiguities
-
-> [!NOTE]
-> This section is incomplete.
-
-r[items.use.ambiguities.intro]
-Some situations are an error when there is an ambiguity as to which name a `use` declaration refers. This happens when there are two name candidates that do not resolve to the same entity.
-
-r[items.use.ambiguities.glob]
-Glob imports are allowed to import conflicting names in the same namespace as long as the name is not used.
-For example:
-
-```rust
-mod foo {
-    pub struct Qux;
-}
-
-mod bar {
-    pub struct Qux;
-}
-
-use foo::*;
-use bar::*; //~ OK, no name conflict.
-
-fn main() {
-    // This would be an error, due to the ambiguity.
-    //let x = Qux;
-}
-```
-
-Multiple glob imports are allowed to import the same name, and that name is allowed to be used, if the imports are of the same item (following re-exports). The visibility of the name is the maximum visibility of the imports. For example:
-
-```rust
-mod foo {
-    pub struct Qux;
-}
-
-mod bar {
-    pub use super::foo::Qux;
-}
-
-// These both import the same `Qux`. The visibility of `Qux`
-// is `pub` because that is the maximum visibility between
-// these two `use` declarations.
-pub use bar::*;
-use foo::*;
-
-fn main() {
-    let _: Qux = Qux;
-}
-```
+TODO mention ambiguities and link to name-res. Moved to name-res because
+ambiguities are fundamentally a product of the place of use, not the use
+declaration.
 
 [`extern crate`]: extern-crates.md
 [`macro_rules`]: ../macros-by-example.md

src/macros-by-example.md

@@ -326,6 +326,59 @@ fn foo() {
 // m!(); // Error: m is not in scope.
 ```
 
+r[macro.decl.scope.textual.shadow.path-based]
+Textual scope name bindings for macros may shadow path-based scope bindings to
+macros.
+
+```rust
+macro_rules! m {
+    () => {
+        println!("m");
+    };
+}
+
+#[macro_export]
+macro_rules! m2 {
+    () => {
+        println!("m2");
+    };
+}
+
+use crate::m2 as m;
+
+m!(); // prints "m\n"
+```
+
+TODO: note that the opposite is not true, link to relevant name-res ambiguity error section
+
+r[macro.decl.scope.path-based]
+### Path-based scope
+
+r[macro.decl.scope.path-based.intro]
+By default, a macro has no path-based scope. Macros can gain path-based scope in two ways:
+
+* [Use declaration re-export]
+* [`#[macro_export]`](macros-by-example.html#the-macro_export-attribute)
+
+r[macro.decl.scope.path.reexport]
+Macros can be re-exported to give them path-based scope from a module other than the crate root.
+
+```rust
+mac::m!(); // OK: Path-based lookup finds m in the mac module.
+
+mod mac {
+    macro_rules! m {
+        () => {};
+    }
+    pub(crate) use m;
+}
+```
+
+r[macro.decl.scope.path-based.visibility]
+* macros have an implicit visibility of `pub(crate)`
+* `#[macro_export]` changes the implicit visibility to `pub`
+* macro definitions do not support direct visibility modifiers
+
 <!-- template:attributes -->
 r[macro.decl.scope.macro_use]
 ### The `macro_use` attribute
@@ -724,3 +777,4 @@ For more detail, see the [formal specification].
 [Repetitions]: #repetitions
 [token]: tokens.md
 [`$crate`]: macro.decl.hygiene.crate
+[Use declaration re-export]: items/use-declarations.html#use-visibility