minor: import Either from either

Cargo.lock

@@ -572,6 +572,7 @@ dependencies = [
  "chalk-recursive",
  "chalk-solve",
  "cov-mark",
+ "either",
  "ena",
  "expect-test",
  "hir-def",
@@ -1714,6 +1715,7 @@ name = "syntax"
 version = "0.0.0"
 dependencies = [
  "cov-mark",
+ "either",
  "expect-test",
  "indexmap",
  "itertools",

crates/hir-ty/Cargo.toml

@@ -18,6 +18,7 @@ arrayvec = "0.7.2"
 bitflags = "1.3.2"
 smallvec.workspace = true
 ena = "0.14.0"
+either = "1.7.0"
 tracing = "0.1.35"
 rustc-hash = "1.1.0"
 scoped-tls = "1.0.0"

crates/hir-ty/src/diagnostics/expr.rs

@@ -5,11 +5,11 @@
 use std::fmt;
 use std::sync::Arc;
 
+use either::Either;
 use hir_def::lang_item::LangItem;
 use hir_def::{resolver::HasResolver, AdtId, AssocItemId, DefWithBodyId, HasModule};
 use hir_def::{ItemContainerId, Lookup};
 use hir_expand::name;
-use itertools::Either;
 use itertools::Itertools;
 use rustc_hash::FxHashSet;
 use typed_arena::Arena;

crates/hir-ty/src/infer.rs

@@ -17,6 +17,7 @@ use std::ops::Index;
 use std::sync::Arc;
 
 use chalk_ir::{cast::Cast, ConstValue, DebruijnIndex, Mutability, Safety, Scalar, TypeFlags};
+use either::Either;
 use hir_def::{
     body::Body,
     builtin_type::{BuiltinInt, BuiltinType, BuiltinUint},
@@ -31,7 +32,6 @@ use hir_def::{
     ItemContainerId, Lookup, TraitId, TypeAliasId, VariantId,
 };
 use hir_expand::name::name;
-use itertools::Either;
 use la_arena::ArenaMap;
 use rustc_hash::FxHashMap;
 use stdx::always;

crates/hir-ty/src/lib.rs

@@ -42,9 +42,9 @@ use chalk_ir::{
     visit::{TypeSuperVisitable, TypeVisitable, TypeVisitor},
     NoSolution, TyData,
 };
+use either::Either;
 use hir_def::{expr::ExprId, type_ref::Rawness, TypeOrConstParamId};
 use hir_expand::name;
-use itertools::Either;
 use la_arena::{Arena, Idx};
 use rustc_hash::FxHashSet;
 use traits::FnTrait;

crates/hir-ty/src/lower.rs

@@ -16,6 +16,7 @@ use chalk_ir::{
     cast::Cast, fold::Shift, fold::TypeFoldable, interner::HasInterner, Mutability, Safety,
 };
 
+use either::Either;
 use hir_def::{
     adt::StructKind,
     body::{Expander, LowerCtx},
@@ -35,7 +36,6 @@ use hir_def::{
 };
 use hir_expand::{name::Name, ExpandResult};
 use intern::Interned;
-use itertools::Either;
 use la_arena::{Arena, ArenaMap};
 use rustc_hash::FxHashSet;
 use smallvec::SmallVec;
@@ -1583,10 +1583,10 @@ pub(crate) fn generic_defaults_recover(
         .iter_id()
         .map(|id| {
             let val = match id {
-                itertools::Either::Left(_) => {
+                Either::Left(_) => {
                     GenericArgData::Ty(TyKind::Error.intern(Interner)).intern(Interner)
                 }
-                itertools::Either::Right(id) => unknown_const_as_generic(db.const_param_ty(id)),
+                Either::Right(id) => unknown_const_as_generic(db.const_param_ty(id)),
             };
             crate::make_binders(db, &generic_params, val)
         })

crates/hir-ty/src/utils.rs

@@ -5,6 +5,7 @@ use std::iter;
 
 use base_db::CrateId;
 use chalk_ir::{cast::Cast, fold::Shift, BoundVar, DebruijnIndex};
+use either::Either;
 use hir_def::{
     db::DefDatabase,
     generics::{
@@ -19,7 +20,6 @@ use hir_def::{
 };
 use hir_expand::name::Name;
 use intern::Interned;
-use itertools::Either;
 use rustc_hash::FxHashSet;
 use smallvec::{smallvec, SmallVec};
 

crates/syntax/Cargo.toml

@@ -14,6 +14,7 @@ doctest = false
 
 [dependencies]
 cov-mark = "2.0.0-pre.1"
+either = "1.7.0"
 itertools = "0.10.5"
 rowan = "0.15.10"
 rustc_lexer = { version = "727.0.0", package = "rustc-ap-rustc_lexer" }

crates/syntax/src/ast.rs

@@ -13,7 +13,7 @@ pub mod prec;
 
 use std::marker::PhantomData;
 
-use itertools::Either;
+use either::Either;
 
 use crate::{
     syntax_node::{SyntaxNode, SyntaxNodeChildren, SyntaxToken},

crates/syntax/src/ast/traits.rs

@@ -1,7 +1,7 @@
 //! Various traits that are implemented by ast nodes.
 //!
 //! The implementations are usually trivial, and live in generated.rs
-use itertools::Either;
+use either::Either;
 
 use crate::{
     ast::{self, support, AstChildren, AstNode, AstToken},