Rename kw::Empty as sym::empty.

Because the empty string is not a keyword.

Author: nnethercote

clippy_lints/src/manual_string_new.rs

@@ -5,7 +5,7 @@ use rustc_hir::{Expr, ExprKind, PathSegment, QPath, TyKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty;
 use rustc_session::declare_lint_pass;
-use rustc_span::{Span, sym, symbol};
+use rustc_span::{Span, sym};
 
 declare_clippy_lint! {
     /// ### What it does
@@ -67,7 +67,7 @@ impl LateLintPass<'_> for ManualStringNew {
 fn is_expr_kind_empty_str(expr_kind: &ExprKind<'_>) -> bool {
     if let ExprKind::Lit(lit) = expr_kind
         && let LitKind::Str(value, _) = lit.node
-        && value == symbol::kw::Empty
+        && value == sym::empty
     {
         return true;
     }

clippy_lints/src/methods/or_fun_call.rs

@@ -12,7 +12,7 @@ use rustc_errors::Applicability;
 use rustc_lint::LateContext;
 use rustc_middle::ty;
 use rustc_span::Span;
-use rustc_span::symbol::{self, Symbol};
+use rustc_span::Symbol;
 use {rustc_ast as ast, rustc_hir as hir};
 
 use super::{OR_FUN_CALL, UNWRAP_OR_DEFAULT};
@@ -265,7 +265,7 @@ fn closure_body_returns_empty_to_string(cx: &LateContext<'_>, e: &hir::Expr<'_>)
             && ident.name == sym::to_string
             && let hir::Expr { kind, .. } = self_arg
             && let hir::ExprKind::Lit(lit) = kind
-            && let ast::LitKind::Str(symbol::kw::Empty, _) = lit.node
+            && let ast::LitKind::Str(rustc_span::sym::empty, _) = lit.node
         {
             return true;
         }