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rewrite bullet points as prose
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6 files changed

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src/items/use-declarations.md

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@@ -116,7 +116,7 @@ They may create bindings for:
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* [Built-in types]
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* [Attributes]
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* [Derive macros]
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* [Macros by example]
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* [`macro_rules`]
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r[items.use.path.disallowed]
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They cannot import [associated items], [generic parameters], [local variables], paths with [`Self`], or [tool attributes]. More restrictions are described below.
@@ -303,6 +303,10 @@ mod clashing {
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}
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```
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> [!NOTE]
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>
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> For areas where shadowing is not allowed, see [name resolution ambiguities].
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r[items.use.glob.last-segment-only]
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`*` cannot be used as the first or intermediate segments.
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@@ -390,10 +394,6 @@ r[items.use.restrictions.variant]
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use TypeAlias::MyVariant; //~ ERROR
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```
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TODO mention ambiguities and link to name-res. Moved to name-res because
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ambiguities are fundamentally a product of the place of use, not the use
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declaration.
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[`extern crate`]: extern-crates.md
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[`macro_rules`]: ../macros-by-example.md
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[`self`]: ../paths.md#self
@@ -412,3 +412,4 @@ declaration.
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[tool attributes]: ../attributes.md#tool-attributes
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[type alias]: type-aliases.md
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[type namespace]: ../names/namespaces.md
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[name resolution ambiguities]: ../names/name-resolution.html#r-names.resolution.expansion.imports.errors.ambiguity

src/macros-by-example.md

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@@ -326,20 +326,22 @@ fn foo() {
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// m!(); // Error: m is not in scope.
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```
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* textual scope name bindings for macros may shadow path-based scope bindings
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to macros
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r[macro.decl.scope.textual.shadow.path-based]
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Textual scope name bindings for macros may shadow path-based scope bindings to macros.
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```rust
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macro_rules! m {
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#[macro_export]
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macro_rules! m2 {
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() => {
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println!("m");
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println!("m2");
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};
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}
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#[macro_export]
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macro_rules! m2 {
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m!(); // prints "m2\n"
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macro_rules! m {
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() => {
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println!("m2");
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println!("m");
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};
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}
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@@ -348,6 +350,53 @@ use crate::m2 as m;
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m!(); // prints "m\n"
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```
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> [!NOTE]
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>
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> For areas where shadowing is not allowed, see [name resolution ambiguities].
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r[macro.decl.scope.path-based]
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### Path-based scope
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r[macro.decl.scope.path-based.intro]
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By default, a macro has no path-based scope. Macros can gain path-based scope in two ways:
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* [Use declaration re-export]
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* [`#[macro_export]`](macros-by-example.html#the-macro_export-attribute)
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r[macro.decl.scope.path.reexport]
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Macros can be re-exported to give them path-based scope from a module other than the crate root.
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```rust
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mac::m!(); // OK: Path-based lookup finds m in the mac module.
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mod mac {
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macro_rules! m {
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() => {};
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}
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pub(crate) use m;
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}
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```
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r[macro.decl.scope.path-based.visibility]
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Macros have an implicit visibility of `pub(crate)`. `#[macro_export]` changes the implicit visibility to `pub`.
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```rust,compile_fail,E0364
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macro_rules! private_m {
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() => {};
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}
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#[macro_export]
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macro_rules! pub_m {
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() => {};
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}
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pub(crate) use private_m as private_macro; // OK
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pub use pub_m as pub_macro; // OK
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pub use private_m; // ERROR: `private_m` is only public within
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// the crate and cannot be re-exported outside
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```
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<!-- template:attributes -->
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r[macro.decl.scope.macro_use]
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### The `macro_use` attribute
@@ -502,25 +551,6 @@ By default, macros only have [textual scope][macro.decl.scope.textual] and canno
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> # fn main() {}
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> ```
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r[macro.decl.scope.path.reexport]
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* macros can be re-exported to give them path-based scope from a module other than the crate root.
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* there's some visibility stuff here that may already be mentioned
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elsewhere. I'm pretty sure that w/o a #[macro_export] the macro being
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re-exported is implicitly pub(crate) and with one it is implicitly pub.
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The later is mentioned below, don't remember where I saw the former.
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```
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mac::m!(); // OK: Path-based lookup finds m in the mac module.
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mod mac {
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macro_rules! m {
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() => {};
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}
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pub(crate) use m;
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}
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```
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r[macro.decl.scope.macro_export.export]
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The `macro_export` attribute causes a macro to be exported from the crate root so that it can be referred to in other crates by path.
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@@ -765,3 +795,5 @@ For more detail, see the [formal specification].
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[Repetitions]: #repetitions
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[token]: tokens.md
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[`$crate`]: macro.decl.hygiene.crate
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[Use declaration re-export]: items/use-declarations.html#use-visibility
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[name resolution ambiguities]: ../names/name-resolution.html#r-names.resolution.expansion.imports.errors.ambiguity

src/macros.md

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@@ -106,6 +106,16 @@ macro_rules! example {
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example!();
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```
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r[macro.invocation.name-resolution]
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Macros invocations can be resolved via two kinds of scopes:
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* Textual Scope
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* [textual scope `macro_rules`](macros-by-example.md#r-macro.decl.scope.textual)
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* Path-based scope
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* [path-based scope `macro_rules`](macros-by-example.md#r-macro.decl.scope.path-based)
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* [Procedural Macros]
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[Macros by Example]: macros-by-example.md
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[Procedural Macros]: procedural-macros.md
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[associated items]: items/associated-items.md

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