Suggest casting on numeric type error

src/librustc/hir/mod.rs

@@ -34,13 +34,14 @@ use util::nodemap::{NodeMap, FxHashSet};
 use syntax_pos::{Span, DUMMY_SP};
 use syntax::codemap::{self, Spanned};
 use syntax::abi::Abi;
-use syntax::ast::{Ident, Name, NodeId, DUMMY_NODE_ID, AsmDialect};
+use syntax::ast::{self, Ident, Name, NodeId, DUMMY_NODE_ID, AsmDialect};
 use syntax::ast::{Attribute, Lit, StrStyle, FloatTy, IntTy, UintTy, MetaItem};
 use syntax::ext::hygiene::SyntaxContext;
 use syntax::ptr::P;
 use syntax::symbol::{Symbol, keywords};
 use syntax::tokenstream::TokenStream;
 use syntax::util::ThinVec;
+use syntax::util::parser::ExprPrecedence;
 use ty::AdtKind;
 
 use rustc_data_structures::indexed_vec;
@@ -958,6 +959,31 @@ impl BinOp_ {
     }
 }
 
+impl Into<ast::BinOpKind> for BinOp_ {
+    fn into(self) -> ast::BinOpKind {
+        match self {
+            BiAdd => ast::BinOpKind::Add,
+            BiSub => ast::BinOpKind::Sub,
+            BiMul => ast::BinOpKind::Mul,
+            BiDiv => ast::BinOpKind::Div,
+            BiRem => ast::BinOpKind::Rem,
+            BiAnd => ast::BinOpKind::And,
+            BiOr => ast::BinOpKind::Or,
+            BiBitXor => ast::BinOpKind::BitXor,
+            BiBitAnd => ast::BinOpKind::BitAnd,
+            BiBitOr => ast::BinOpKind::BitOr,
+            BiShl => ast::BinOpKind::Shl,
+            BiShr => ast::BinOpKind::Shr,
+            BiEq => ast::BinOpKind::Eq,
+            BiLt => ast::BinOpKind::Lt,
+            BiLe => ast::BinOpKind::Le,
+            BiNe => ast::BinOpKind::Ne,
+            BiGe => ast::BinOpKind::Ge,
+            BiGt => ast::BinOpKind::Gt,
+        }
+    }
+}
+
 pub type BinOp = Spanned<BinOp_>;
 
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
@@ -1166,6 +1192,42 @@ pub struct Expr {
     pub hir_id: HirId,
 }
 
+impl Expr {
+    pub fn precedence(&self) -> ExprPrecedence {
+        match self.node {
+            ExprBox(_) => ExprPrecedence::Box,
+            ExprArray(_) => ExprPrecedence::Array,
+            ExprCall(..) => ExprPrecedence::Call,
+            ExprMethodCall(..) => ExprPrecedence::MethodCall,
+            ExprTup(_) => ExprPrecedence::Tup,
+            ExprBinary(op, ..) => ExprPrecedence::Binary(op.node.into()),
+            ExprUnary(..) => ExprPrecedence::Unary,
+            ExprLit(_) => ExprPrecedence::Lit,
+            ExprType(..) | ExprCast(..) => ExprPrecedence::Cast,
+            ExprIf(..) => ExprPrecedence::If,
+            ExprWhile(..) => ExprPrecedence::While,
+            ExprLoop(..) => ExprPrecedence::Loop,
+            ExprMatch(..) => ExprPrecedence::Match,
+            ExprClosure(..) => ExprPrecedence::Closure,
+            ExprBlock(..) => ExprPrecedence::Block,
+            ExprAssign(..) => ExprPrecedence::Assign,
+            ExprAssignOp(..) => ExprPrecedence::AssignOp,
+            ExprField(..) => ExprPrecedence::Field,
+            ExprTupField(..) => ExprPrecedence::TupField,
+            ExprIndex(..) => ExprPrecedence::Index,
+            ExprPath(..) => ExprPrecedence::Path,
+            ExprAddrOf(..) => ExprPrecedence::AddrOf,
+            ExprBreak(..) => ExprPrecedence::Break,
+            ExprAgain(..) => ExprPrecedence::Continue,
+            ExprRet(..) => ExprPrecedence::Ret,
+            ExprInlineAsm(..) => ExprPrecedence::InlineAsm,
+            ExprStruct(..) => ExprPrecedence::Struct,
+            ExprRepeat(..) => ExprPrecedence::Repeat,
+            ExprYield(..) => ExprPrecedence::Yield,
+        }
+    }
+}
+
 impl fmt::Debug for Expr {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(f, "expr({}: {})", self.id,

src/librustc/hir/print.rs

@@ -1104,7 +1104,7 @@ impl<'a> State<'a> {
     }
 
     pub fn print_expr_maybe_paren(&mut self, expr: &hir::Expr, prec: i8) -> io::Result<()> {
-        let needs_par = expr_precedence(expr) < prec;
+        let needs_par = expr.precedence().order() < prec;
         if needs_par {
             self.popen()?;
         }
@@ -2318,55 +2318,6 @@ fn stmt_ends_with_semi(stmt: &hir::Stmt_) -> bool {
     }
 }
 
-
-fn expr_precedence(expr: &hir::Expr) -> i8 {
-    use syntax::util::parser::*;
-
-    match expr.node {
-        hir::ExprClosure(..) => PREC_CLOSURE,
-
-        hir::ExprBreak(..) |
-        hir::ExprAgain(..) |
-        hir::ExprRet(..) |
-        hir::ExprYield(..) => PREC_JUMP,
-
-        // Binop-like expr kinds, handled by `AssocOp`.
-        hir::ExprBinary(op, _, _) => bin_op_to_assoc_op(op.node).precedence() as i8,
-
-        hir::ExprCast(..) => AssocOp::As.precedence() as i8,
-        hir::ExprType(..) => AssocOp::Colon.precedence() as i8,
-
-        hir::ExprAssign(..) |
-        hir::ExprAssignOp(..) => AssocOp::Assign.precedence() as i8,
-
-        // Unary, prefix
-        hir::ExprBox(..) |
-        hir::ExprAddrOf(..) |
-        hir::ExprUnary(..) => PREC_PREFIX,
-
-        // Unary, postfix
-        hir::ExprCall(..) |
-        hir::ExprMethodCall(..) |
-        hir::ExprField(..) |
-        hir::ExprTupField(..) |
-        hir::ExprIndex(..) |
-        hir::ExprInlineAsm(..) => PREC_POSTFIX,
-
-        // Never need parens
-        hir::ExprArray(..) |
-        hir::ExprRepeat(..) |
-        hir::ExprTup(..) |
-        hir::ExprLit(..) |
-        hir::ExprPath(..) |
-        hir::ExprIf(..) |
-        hir::ExprWhile(..) |
-        hir::ExprLoop(..) |
-        hir::ExprMatch(..) |
-        hir::ExprBlock(..) |
-        hir::ExprStruct(..) => PREC_PAREN,
-    }
-}
-
 fn bin_op_to_assoc_op(op: hir::BinOp_) -> AssocOp {
     use hir::BinOp_::*;
     match op {