Use Lit rather than P<Lit> in ast::ExprKind.

Because it results in fewer allocations and small speedups on some
benchmarks.

src/librustc/hir/lowering.rs

@@ -3705,7 +3705,7 @@ impl<'a> LoweringContext<'a> {
                 let ohs = P(self.lower_expr(ohs));
                 hir::ExprKind::Unary(op, ohs)
             }
-            ExprKind::Lit(ref l) => hir::ExprKind::Lit(P((**l).clone())),
+            ExprKind::Lit(ref l) => hir::ExprKind::Lit(P((*l).clone())),
             ExprKind::Cast(ref expr, ref ty) => {
                 let expr = P(self.lower_expr(expr));
                 hir::ExprKind::Cast(expr, self.lower_ty(ty, ImplTraitContext::disallowed()))

src/libsyntax/ast.rs

@@ -1086,7 +1086,7 @@ pub enum ExprKind {
     /// A unary operation (For example: `!x`, `*x`)
     Unary(UnOp, P<Expr>),
     /// A literal (For example: `1`, `"foo"`)
-    Lit(P<Lit>),
+    Lit(Lit),
     /// A cast (`foo as f64`)
     Cast(P<Expr>, P<Ty>),
     Type(P<Expr>, P<Ty>),

src/libsyntax/ext/base.rs

@@ -491,7 +491,7 @@ impl DummyResult {
     pub fn raw_expr(sp: Span) -> P<ast::Expr> {
         P(ast::Expr {
             id: ast::DUMMY_NODE_ID,
-            node: ast::ExprKind::Lit(P(source_map::respan(sp, ast::LitKind::Bool(false)))),
+            node: ast::ExprKind::Lit(source_map::respan(sp, ast::LitKind::Bool(false))),
             span: sp,
             attrs: ThinVec::new(),
         })

src/libsyntax/ext/build.rs

@@ -695,7 +695,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
     }
 
     fn expr_lit(&self, sp: Span, lit: ast::LitKind) -> P<ast::Expr> {
-        self.expr(sp, ast::ExprKind::Lit(P(respan(sp, lit))))
+        self.expr(sp, ast::ExprKind::Lit(respan(sp, lit)))
     }
     fn expr_usize(&self, span: Span, i: usize) -> P<ast::Expr> {
         self.expr_lit(span, ast::LitKind::Int(i as u128,

src/libsyntax/ext/quote.rs

@@ -274,7 +274,7 @@ pub mod rt {
             // FIXME: This is wrong
             P(ast::Expr {
                 id: ast::DUMMY_NODE_ID,
-                node: ast::ExprKind::Lit(P(self.clone())),
+                node: ast::ExprKind::Lit(self.clone()),
                 span: DUMMY_SP,
                 attrs: ThinVec::new(),
             }).to_tokens(cx)
@@ -305,7 +305,7 @@ pub mod rt {
                     let lit = ast::LitKind::Int(val as u128, ast::LitIntType::Signed($tag));
                     let lit = P(ast::Expr {
                         id: ast::DUMMY_NODE_ID,
-                        node: ast::ExprKind::Lit(P(dummy_spanned(lit))),
+                        node: ast::ExprKind::Lit(dummy_spanned(lit)),
                         span: DUMMY_SP,
                         attrs: ThinVec::new(),
                     });

src/libsyntax/parse/parser.rs

@@ -1957,7 +1957,7 @@ impl<'a> Parser<'a> {
         let minus_lo = self.span;
         let minus_present = self.eat(&token::BinOp(token::Minus));
         let lo = self.span;
-        let literal = P(self.parse_lit()?);
+        let literal = self.parse_lit()?;
         let hi = self.prev_span;
         let expr = self.mk_expr(lo.to(hi), ExprKind::Lit(literal), ThinVec::new());