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Fix documentation highlighting in ty::BorrowKind
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jyn514 committed Sep 25, 2020
1 parent cbc5e4d commit 58d57f3
Showing 1 changed file with 16 additions and 10 deletions.
26 changes: 16 additions & 10 deletions compiler/rustc_middle/src/ty/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -682,25 +682,31 @@ pub enum BorrowKind {
/// implicit closure bindings. It is needed when the closure
/// is borrowing or mutating a mutable referent, e.g.:
///
/// let x: &mut isize = ...;
/// let y = || *x += 5;
/// ```
/// let x: &mut isize = ...;
/// let y = || *x += 5;
/// ```
///
/// If we were to try to translate this closure into a more explicit
/// form, we'd encounter an error with the code as written:
///
/// struct Env { x: & &mut isize }
/// let x: &mut isize = ...;
/// let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn
/// fn fn_ptr(env: &mut Env) { **env.x += 5; }
/// ```
/// struct Env { x: & &mut isize }
/// let x: &mut isize = ...;
/// let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn
/// fn fn_ptr(env: &mut Env) { **env.x += 5; }
/// ```
///
/// This is then illegal because you cannot mutate a `&mut` found
/// in an aliasable location. To solve, you'd have to translate with
/// an `&mut` borrow:
///
/// struct Env { x: & &mut isize }
/// let x: &mut isize = ...;
/// let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x
/// fn fn_ptr(env: &mut Env) { **env.x += 5; }
/// ```
/// struct Env { x: & &mut isize }
/// let x: &mut isize = ...;
/// let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x
/// fn fn_ptr(env: &mut Env) { **env.x += 5; }
/// ```
///
/// Now the assignment to `**env.x` is legal, but creating a
/// mutable pointer to `x` is not because `x` is not mutable. We
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