Auto merge of #134243 - nnethercote:re-export-more-rustc_span, r=jieyouxu

Re-export more `rustc_span::symbol` things from `rustc_span`.

`rustc_span::symbol` defines some things that are re-exported from `rustc_span`, such as `Symbol` and `sym`. But it doesn't re-export some closely related things such as `Ident` and `kw`. So you can do `use rustc_span::{Symbol, sym}` but you have to do `use rustc_span::symbol::{Ident, kw}`, which is inconsistent for no good reason.

This commit re-exports `Ident`, `kw`, and `MacroRulesNormalizedIdent`, and changes many `rustc_span::symbol::` qualifiers to `rustc_span::`. This is a 300+ net line of code reduction, mostly because many files with two `use rustc_span` items can be reduced to one.

r? `@jieyouxu`

compiler/rustc_trait_selection/src/traits/coherence.rs

@@ -21,8 +21,7 @@ use rustc_middle::ty::visit::{TypeSuperVisitable, TypeVisitable, TypeVisitableEx
 use rustc_middle::ty::{self, Ty, TyCtxt, TypingMode};
 pub use rustc_next_trait_solver::coherence::*;
 use rustc_next_trait_solver::solve::SolverDelegateEvalExt;
-use rustc_span::symbol::sym;
-use rustc_span::{DUMMY_SP, Span};
+use rustc_span::{DUMMY_SP, Span, sym};
 use tracing::{debug, instrument, warn};
 
 use super::ObligationCtxt;

compiler/rustc_trait_selection/src/traits/project.rs

@@ -17,7 +17,7 @@ use rustc_middle::ty::fold::TypeFoldable;
 use rustc_middle::ty::visit::TypeVisitableExt;
 use rustc_middle::ty::{self, Term, Ty, TyCtxt, TypingMode, Upcast};
 use rustc_middle::{bug, span_bug};
-use rustc_span::symbol::sym;
+use rustc_span::sym;
 use thin_vec::thin_vec;
 use tracing::{debug, instrument};
 

compiler/rustc_trait_selection/src/traits/select/mod.rs

@@ -31,8 +31,7 @@ use rustc_middle::ty::{
     self, GenericArgsRef, PolyProjectionPredicate, Ty, TyCtxt, TypeFoldable, TypeVisitableExt,
     TypingMode, Upcast,
 };
-use rustc_span::Symbol;
-use rustc_span::symbol::sym;
+use rustc_span::{Symbol, sym};
 use tracing::{debug, instrument, trace};
 
 use self::EvaluationResult::*;