Remove hir::BinOp, hir::BinOpKind, and hir::UnOp.

They're identical to the same-named types from `ast`. I find it silly
(and inefficient) to have all this boilerplate code to convert one type
to an identical type.

There is already a small amount of type sharing between the AST and HIR,
e.g. `Attribute`, `MacroDef`.

The commit adds a `pub use` to `rustc_hir` so that, for example,
`ast::BinOp` can also be referred to as `hir::BinOp`. This is so the
many existing `hir`-qualified mentions of these types don't need to
change.

The commit also moves a couple of operations from the (removed) HIR
types to the AST types, e.g. `is_by_value`.

compiler/rustc_ast/src/ast.rs

@@ -817,7 +817,7 @@ pub enum BorrowKind {
     Raw,
 }
 
-#[derive(Clone, PartialEq, Encodable, Decodable, Debug, Copy)]
+#[derive(Clone, Copy, Debug, PartialEq, Encodable, Decodable, HashStable_Generic)]
 pub enum BinOpKind {
     /// The `+` operator (addition)
     Add,
@@ -888,21 +888,26 @@ impl BinOpKind {
 
     pub fn is_comparison(&self) -> bool {
         use BinOpKind::*;
-        // Note for developers: please keep this as is;
+        // Note for developers: please keep this match exhaustive;
         // we want compilation to fail if another variant is added.
         match *self {
             Eq | Lt | Le | Ne | Gt | Ge => true,
             And | Or | Add | Sub | Mul | Div | Rem | BitXor | BitAnd | BitOr | Shl | Shr => false,
         }
     }
+
+    /// Returns `true` if the binary operator takes its arguments by value.
+    pub fn is_by_value(self) -> bool {
+        !self.is_comparison()
+    }
 }
 
 pub type BinOp = Spanned<BinOpKind>;
 
 /// Unary operator.
 ///
 /// Note that `&data` is not an operator, it's an `AddrOf` expression.
-#[derive(Clone, Encodable, Decodable, Debug, Copy)]
+#[derive(Clone, Copy, Debug, PartialEq, Encodable, Decodable, HashStable_Generic)]
 pub enum UnOp {
     /// The `*` operator for dereferencing
     Deref,
@@ -920,6 +925,11 @@ impl UnOp {
             UnOp::Neg => "-",
         }
     }
+
+    /// Returns `true` if the unary operator takes its argument by value.
+    pub fn is_by_value(self) -> bool {
+        matches!(self, Self::Neg | Self::Not)
+    }
 }
 
 /// A statement

compiler/rustc_ast_lowering/src/expr.rs

@@ -350,30 +350,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
         }
     }
 
-    fn lower_binop(&mut self, b: BinOp) -> hir::BinOp {
-        Spanned {
-            node: match b.node {
-                BinOpKind::Add => hir::BinOpKind::Add,
-                BinOpKind::Sub => hir::BinOpKind::Sub,
-                BinOpKind::Mul => hir::BinOpKind::Mul,
-                BinOpKind::Div => hir::BinOpKind::Div,
-                BinOpKind::Rem => hir::BinOpKind::Rem,
-                BinOpKind::And => hir::BinOpKind::And,
-                BinOpKind::Or => hir::BinOpKind::Or,
-                BinOpKind::BitXor => hir::BinOpKind::BitXor,
-                BinOpKind::BitAnd => hir::BinOpKind::BitAnd,
-                BinOpKind::BitOr => hir::BinOpKind::BitOr,
-                BinOpKind::Shl => hir::BinOpKind::Shl,
-                BinOpKind::Shr => hir::BinOpKind::Shr,
-                BinOpKind::Eq => hir::BinOpKind::Eq,
-                BinOpKind::Lt => hir::BinOpKind::Lt,
-                BinOpKind::Le => hir::BinOpKind::Le,
-                BinOpKind::Ne => hir::BinOpKind::Ne,
-                BinOpKind::Ge => hir::BinOpKind::Ge,
-                BinOpKind::Gt => hir::BinOpKind::Gt,
-            },
-            span: self.lower_span(b.span),
-        }
+    fn lower_binop(&mut self, b: BinOp) -> BinOp {
+        Spanned { node: b.node, span: self.lower_span(b.span) }
     }
 
     fn lower_legacy_const_generics(

compiler/rustc_hir/src/hir.rs

@@ -7,6 +7,7 @@ use crate::LangItem;
 use rustc_ast as ast;
 use rustc_ast::util::parser::ExprPrecedence;
 use rustc_ast::{Attribute, FloatTy, IntTy, Label, LitKind, TraitObjectSyntax, UintTy};
+pub use rustc_ast::{BinOp, BinOpKind, UnOp}; // shared between AST and HIR
 pub use rustc_ast::{BindingAnnotation, BorrowKind, ByRef, ImplPolarity, IsAuto};
 pub use rustc_ast::{CaptureBy, Movability, Mutability};
 use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
@@ -1174,155 +1175,6 @@ pub enum PatKind<'hir> {
     Slice(&'hir [Pat<'hir>], Option<&'hir Pat<'hir>>, &'hir [Pat<'hir>]),
 }
 
-#[derive(Copy, Clone, PartialEq, Debug, HashStable_Generic)]
-pub enum BinOpKind {
-    /// The `+` operator (addition).
-    Add,
-    /// The `-` operator (subtraction).
-    Sub,
-    /// The `*` operator (multiplication).
-    Mul,
-    /// The `/` operator (division).
-    Div,
-    /// The `%` operator (modulus).
-    Rem,
-    /// The `&&` operator (logical and).
-    And,
-    /// The `||` operator (logical or).
-    Or,
-    /// The `^` operator (bitwise xor).
-    BitXor,
-    /// The `&` operator (bitwise and).
-    BitAnd,
-    /// The `|` operator (bitwise or).
-    BitOr,
-    /// The `<<` operator (shift left).
-    Shl,
-    /// The `>>` operator (shift right).
-    Shr,
-    /// The `==` operator (equality).
-    Eq,
-    /// The `<` operator (less than).
-    Lt,
-    /// The `<=` operator (less than or equal to).
-    Le,
-    /// The `!=` operator (not equal to).
-    Ne,
-    /// The `>=` operator (greater than or equal to).
-    Ge,
-    /// The `>` operator (greater than).
-    Gt,
-}
-
-impl BinOpKind {
-    pub fn as_str(self) -> &'static str {
-        match self {
-            BinOpKind::Add => "+",
-            BinOpKind::Sub => "-",
-            BinOpKind::Mul => "*",
-            BinOpKind::Div => "/",
-            BinOpKind::Rem => "%",
-            BinOpKind::And => "&&",
-            BinOpKind::Or => "||",
-            BinOpKind::BitXor => "^",
-            BinOpKind::BitAnd => "&",
-            BinOpKind::BitOr => "|",
-            BinOpKind::Shl => "<<",
-            BinOpKind::Shr => ">>",
-            BinOpKind::Eq => "==",
-            BinOpKind::Lt => "<",
-            BinOpKind::Le => "<=",
-            BinOpKind::Ne => "!=",
-            BinOpKind::Ge => ">=",
-            BinOpKind::Gt => ">",
-        }
-    }
-
-    pub fn is_lazy(self) -> bool {
-        matches!(self, BinOpKind::And | BinOpKind::Or)
-    }
-
-    pub fn is_comparison(self) -> bool {
-        match self {
-            BinOpKind::Eq
-            | BinOpKind::Lt
-            | BinOpKind::Le
-            | BinOpKind::Ne
-            | BinOpKind::Gt
-            | BinOpKind::Ge => true,
-            BinOpKind::And
-            | BinOpKind::Or
-            | BinOpKind::Add
-            | BinOpKind::Sub
-            | BinOpKind::Mul
-            | BinOpKind::Div
-            | BinOpKind::Rem
-            | BinOpKind::BitXor
-            | BinOpKind::BitAnd
-            | BinOpKind::BitOr
-            | BinOpKind::Shl
-            | BinOpKind::Shr => false,
-        }
-    }
-
-    /// Returns `true` if the binary operator takes its arguments by value.
-    pub fn is_by_value(self) -> bool {
-        !self.is_comparison()
-    }
-}
-
-impl Into<ast::BinOpKind> for BinOpKind {
-    fn into(self) -> ast::BinOpKind {
-        match self {
-            BinOpKind::Add => ast::BinOpKind::Add,
-            BinOpKind::Sub => ast::BinOpKind::Sub,
-            BinOpKind::Mul => ast::BinOpKind::Mul,
-            BinOpKind::Div => ast::BinOpKind::Div,
-            BinOpKind::Rem => ast::BinOpKind::Rem,
-            BinOpKind::And => ast::BinOpKind::And,
-            BinOpKind::Or => ast::BinOpKind::Or,
-            BinOpKind::BitXor => ast::BinOpKind::BitXor,
-            BinOpKind::BitAnd => ast::BinOpKind::BitAnd,
-            BinOpKind::BitOr => ast::BinOpKind::BitOr,
-            BinOpKind::Shl => ast::BinOpKind::Shl,
-            BinOpKind::Shr => ast::BinOpKind::Shr,
-            BinOpKind::Eq => ast::BinOpKind::Eq,
-            BinOpKind::Lt => ast::BinOpKind::Lt,
-            BinOpKind::Le => ast::BinOpKind::Le,
-            BinOpKind::Ne => ast::BinOpKind::Ne,
-            BinOpKind::Ge => ast::BinOpKind::Ge,
-            BinOpKind::Gt => ast::BinOpKind::Gt,
-        }
-    }
-}
-
-pub type BinOp = Spanned<BinOpKind>;
-
-#[derive(Copy, Clone, PartialEq, Debug, HashStable_Generic)]
-pub enum UnOp {
-    /// The `*` operator (dereferencing).
-    Deref,
-    /// The `!` operator (logical negation).
-    Not,
-    /// The `-` operator (negation).
-    Neg,
-}
-
-impl UnOp {
-    pub fn as_str(self) -> &'static str {
-        match self {
-            Self::Deref => "*",
-            Self::Not => "!",
-            Self::Neg => "-",
-        }
-    }
-
-    /// Returns `true` if the unary operator takes its argument by value.
-    pub fn is_by_value(self) -> bool {
-        matches!(self, Self::Neg | Self::Not)
-    }
-}
-
 /// A statement.
 #[derive(Debug, Clone, Copy, HashStable_Generic)]
 pub struct Stmt<'hir> {