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Rollup merge of #94312 - pierwill:fix-94311-lattice-docs, r=jackh726

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Edit `rustc_trait_selection::infer::lattice` docs

Closes #94311.

Removes mentions of outdated/missing type and filename (`infer.rs` and `LatticeValue`).
This commit is contained in:
Dylan DPC 2022-03-09 06:38:50 +01:00 committed by GitHub
commit 2b17c27626
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3 changed files with 20 additions and 12 deletions
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2
compiler/rustc_infer/src/infer/glb.rs
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@ -1,3 +1,5 @@
//! Greatest lower bound. See [`lattice`].
use super::combine::CombineFields;
use super::lattice::{self, LatticeDir};
use super::InferCtxt;

28
compiler/rustc_infer/src/infer/lattice.rs
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@ -1,23 +1,21 @@
//! # Lattice Variables
//! # Lattice variables
//!
//! This file contains generic code for operating on inference variables
//! that are characterized by an upper- and lower-bound. The logic and
//! reasoning is explained in detail in the large comment in `infer.rs`.
//! Generic code for operating on [lattices] of inference variables
//! that are characterized by an upper- and lower-bound.
//!
//! The code in here is defined quite generically so that it can be
//! The code is defined quite generically so that it can be
//! applied both to type variables, which represent types being inferred,
//! and fn variables, which represent function types being inferred.
//! It may eventually be applied to their types as well, who knows.
//! (It may eventually be applied to their types as well.)
//! In some cases, the functions are also generic with respect to the
//! operation on the lattice (GLB vs LUB).
//!
//! Although all the functions are generic, we generally write the
//! comments in a way that is specific to type variables and the LUB
//! operation. It's just easier that way.
//! ## Note
//!
//! In general all of the functions are defined parametrically
//! over a `LatticeValue`, which is a value defined with respect to
//! a lattice.
//! Although all the functions are generic, for simplicity, comments in the source code
//! generally refer to type variables and the LUB operation.
//!
//! [lattices]: https://en.wikipedia.org/wiki/Lattice_(order)
use super::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
use super::InferCtxt;
@ -27,6 +25,11 @@ use rustc_middle::ty::relate::{RelateResult, TypeRelation};
use rustc_middle::ty::TyVar;
use rustc_middle::ty::{self, Ty};
/// Trait for returning data about a lattice, and for abstracting
/// over the "direction" of the lattice operation (LUB/GLB).
///
/// GLB moves "down" the lattice (to smaller values); LUB moves
/// "up" the lattice (to bigger values).
pub trait LatticeDir<'f, 'tcx>: TypeRelation<'tcx> {
fn infcx(&self) -> &'f InferCtxt<'f, 'tcx>;
@ -41,6 +44,7 @@ pub trait LatticeDir<'f, 'tcx>: TypeRelation<'tcx> {
fn relate_bound(&mut self, v: Ty<'tcx>, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, ()>;
}
/// Relates two types using a given lattice.
pub fn super_lattice_tys<'a, 'tcx: 'a, L>(
this: &mut L,
a: Ty<'tcx>,

2
compiler/rustc_infer/src/infer/lub.rs
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@ -1,3 +1,5 @@
//! Least upper bound. See [`lattice`].
use super::combine::CombineFields;
use super::lattice::{self, LatticeDir};
use super::InferCtxt;