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Remove outdated references to @T from comments #67394

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Dec 19, 2019
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Remove outdated references to @T from comments #67394

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9 changes: 2 additions & 7 deletions src/libsyntax/ptr.rs
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Original file line number Diff line number Diff line change
@@ -1,17 +1,12 @@
//! The AST pointer.
//!
//! Provides `P<T>`, a frozen owned smart pointer, as a replacement for `@T` in
//! the AST.
//! Provides `P<T>`, a frozen owned smart pointer.
//!
//! # Motivations and benefits
//!
//! * **Identity**: sharing AST nodes is problematic for the various analysis
//! passes (e.g., one may be able to bypass the borrow checker with a shared
//! `ExprKind::AddrOf` node taking a mutable borrow). The only reason `@T` in the
//! AST hasn't caused issues is because of inefficient folding passes which
//! would always deduplicate any such shared nodes. Even if the AST were to
//! switch to an arena, this would still hold, i.e., it couldn't use `&'a T`,
//! but rather a wrapper like `P<'a, T>`.
//! `ExprKind::AddrOf` node taking a mutable borrow).
//!
//! * **Immutability**: `P<T>` disallows mutating its inner `T`, unlike `Box<T>`
//! (unless it contains an `Unsafe` interior, but that may be denied later).
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