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rewrite bullet points as prose
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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.

src/macros-by-example.md

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@@ -326,8 +326,9 @@ 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
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macros.
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```rust
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macro_rules! m {
@@ -348,6 +349,38 @@ use crate::m2 as m;
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m!(); // prints "m\n"
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```
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TODO: note that the opposite is not true, link to relevant name-res ambiguity error section
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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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TODO: intro to path based scope, find old version
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There are two ways to gain path-based scope for MBE macros:
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* `#[macro_export]`
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* [Use declaration re-export]
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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)`
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* `#[macro_export]` changes the implicit visibility to `pub`
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* macro definitions do not support direct visibility modifiers
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<!-- template:attributes -->
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r[macro.decl.scope.macro_use]
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### The `macro_use` attribute
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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 +779,4 @@ 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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