Auto merge of #23673 - nikomatsakis:issue-23319-binops-ng-5, r=pnkfelix

The current binary operator code assumed that if the LHS was a scalar (`i32` etc), then the RHS had to match. This is not true with multidispatch. This PR generalizes the existing code to (primarily) use the traits -- this also allows us to defer the precise type-checking when the types aren't fully known. The one caveat is the unstable SIMD types, which don't fit in with the current traits -- in that case, the LHS type must be known to be SIMD ahead of time.

There is one semi-hacky bit in that during writeback, for builtin operators, if the types resolve to scalars (i32 etc) then we clear the method override. This is because we know what the semantics are and it is more efficient to generate the code directly. It also ensures that we can use these overloaded operators in constants and so forth.

cc @japaric
cc @aturon 

Fixes #23319 (and others).

Author: bors

src/libcollectionstest/bench.rs

@@ -22,13 +22,13 @@ macro_rules! map_insert_rand_bench {
             let mut rng = rand::weak_rng();
 
             for _ in 0..n {
-                let i = rng.gen() % n;
+                let i = rng.gen::<usize>() % n;
                 map.insert(i, i);
             }
 
             // measure
             b.iter(|| {
-                let k = rng.gen() % n;
+                let k = rng.gen::<usize>() % n;
                 map.insert(k, k);
                 map.remove(&k);
             });
@@ -77,7 +77,7 @@ macro_rules! map_find_rand_bench {
 
             // setup
             let mut rng = rand::weak_rng();
-            let mut keys: Vec<_> = (0..n).map(|_| rng.gen() % n).collect();
+            let mut keys: Vec<_> = (0..n).map(|_| rng.gen::<usize>() % n).collect();
 
             for &k in &keys {
                 map.insert(k, k);

src/libcore/ops.rs

@@ -485,6 +485,7 @@ pub trait Neg {
 macro_rules! neg_impl {
     ($($t:ty)*) => ($(
         #[stable(feature = "rust1", since = "1.0.0")]
+        #[allow(unsigned_negation)]
         impl Neg for $t {
             #[stable(feature = "rust1", since = "1.0.0")]
             type Output = $t;
@@ -498,28 +499,7 @@ macro_rules! neg_impl {
     )*)
 }
 
-macro_rules! neg_uint_impl {
-    ($t:ty, $t_signed:ty) => {
-        #[stable(feature = "rust1", since = "1.0.0")]
-        impl Neg for $t {
-            type Output = $t;
-
-            #[inline]
-            fn neg(self) -> $t { -(self as $t_signed) as $t }
-        }
-
-        forward_ref_unop! { impl Neg, neg for $t }
-    }
-}
-
-neg_impl! { isize i8 i16 i32 i64 f32 f64 }
-
-neg_uint_impl! { usize, isize }
-neg_uint_impl! { u8, i8 }
-neg_uint_impl! { u16, i16 }
-neg_uint_impl! { u32, i32 }
-neg_uint_impl! { u64, i64 }
-
+neg_impl! { usize u8 u16 u32 u64 isize i8 i16 i32 i64 f32 f64 }
 
 /// The `Not` trait is used to specify the functionality of unary `!`.
 ///

src/librand/distributions/mod.rs

@@ -256,7 +256,7 @@ fn ziggurat<R: Rng, P, Z>(
             return zero_case(rng, u);
         }
         // algebraically equivalent to f1 + DRanU()*(f0 - f1) < 1
-        if f_tab[i + 1] + (f_tab[i] - f_tab[i + 1]) * rng.gen() < pdf(x) {
+        if f_tab[i + 1] + (f_tab[i] - f_tab[i + 1]) * rng.gen::<f64>() < pdf(x) {
             return x;
         }
     }

src/librand/distributions/range.rs

@@ -154,7 +154,7 @@ macro_rules! float_impl {
                 }
             }
             fn sample_range<R: Rng>(r: &Range<$ty>, rng: &mut R) -> $ty {
-                r.low + r.range * rng.gen()
+                r.low + r.range * rng.gen::<$ty>()
             }
         }
     }

src/librustc/middle/ty.rs

@@ -3039,6 +3039,10 @@ pub fn mk_nil<'tcx>(cx: &ctxt<'tcx>) -> Ty<'tcx> {
     mk_tup(cx, Vec::new())
 }
 
+pub fn mk_bool<'tcx>(cx: &ctxt<'tcx>) -> Ty<'tcx> {
+    mk_t(cx, ty_bool)
+}
+
 pub fn mk_bare_fn<'tcx>(cx: &ctxt<'tcx>,
                         opt_def_id: Option<ast::DefId>,
                         fty: &'tcx BareFnTy<'tcx>) -> Ty<'tcx> {
@@ -3406,8 +3410,12 @@ pub fn type_is_scalar(ty: Ty) -> bool {
 /// Returns true if this type is a floating point type and false otherwise.
 pub fn type_is_floating_point(ty: Ty) -> bool {
     match ty.sty {
-        ty_float(_) => true,
-        _ => false,
+        ty_float(_) |
+        ty_infer(FloatVar(_)) =>
+            true,
+
+        _ =>
+            false,
     }
 }
 
@@ -5805,78 +5813,6 @@ pub fn closure_upvars<'tcx>(typer: &mc::Typer<'tcx>,
     }
 }
 
-pub fn is_binopable<'tcx>(cx: &ctxt<'tcx>, ty: Ty<'tcx>, op: ast::BinOp) -> bool {
-    #![allow(non_upper_case_globals)]
-    const tycat_other: isize = 0;
-    const tycat_bool: isize = 1;
-    const tycat_char: isize = 2;
-    const tycat_int: isize = 3;
-    const tycat_float: isize = 4;
-    const tycat_raw_ptr: isize = 6;
-
-    const opcat_add: isize = 0;
-    const opcat_sub: isize = 1;
-    const opcat_mult: isize = 2;
-    const opcat_shift: isize = 3;
-    const opcat_rel: isize = 4;
-    const opcat_eq: isize = 5;
-    const opcat_bit: isize = 6;
-    const opcat_logic: isize = 7;
-    const opcat_mod: isize = 8;
-
-    fn opcat(op: ast::BinOp) -> isize {
-        match op.node {
-          ast::BiAdd => opcat_add,
-          ast::BiSub => opcat_sub,
-          ast::BiMul => opcat_mult,
-          ast::BiDiv => opcat_mult,
-          ast::BiRem => opcat_mod,
-          ast::BiAnd => opcat_logic,
-          ast::BiOr => opcat_logic,
-          ast::BiBitXor => opcat_bit,
-          ast::BiBitAnd => opcat_bit,
-          ast::BiBitOr => opcat_bit,
-          ast::BiShl => opcat_shift,
-          ast::BiShr => opcat_shift,
-          ast::BiEq => opcat_eq,
-          ast::BiNe => opcat_eq,
-          ast::BiLt => opcat_rel,
-          ast::BiLe => opcat_rel,
-          ast::BiGe => opcat_rel,
-          ast::BiGt => opcat_rel
-        }
-    }
-
-    fn tycat<'tcx>(cx: &ctxt<'tcx>, ty: Ty<'tcx>) -> isize {
-        if type_is_simd(cx, ty) {
-            return tycat(cx, simd_type(cx, ty))
-        }
-        match ty.sty {
-          ty_char => tycat_char,
-          ty_bool => tycat_bool,
-          ty_int(_) | ty_uint(_) | ty_infer(IntVar(_)) => tycat_int,
-          ty_float(_) | ty_infer(FloatVar(_)) => tycat_float,
-          ty_ptr(_) => tycat_raw_ptr,
-          _ => tycat_other
-        }
-    }
-
-    const t: bool = true;
-    const f: bool = false;
-
-    let tbl = [
-    //           +, -, *, shift, rel, ==, bit, logic, mod
-    /*other*/   [f, f, f, f,     f,   f,  f,   f,     f],
-    /*bool*/    [f, f, f, f,     t,   t,  t,   t,     f],
-    /*char*/    [f, f, f, f,     t,   t,  f,   f,     f],
-    /*isize*/     [t, t, t, t,     t,   t,  t,   f,     t],
-    /*float*/   [t, t, t, f,     t,   t,  f,   f,     f],
-    /*bot*/     [t, t, t, t,     t,   t,  t,   t,     t],
-    /*raw ptr*/ [f, f, f, f,     t,   t,  f,   f,     f]];
-
-    return tbl[tycat(cx, ty) as usize ][opcat(op) as usize];
-}
-
 // Returns the repeat count for a repeating vector expression.
 pub fn eval_repeat_count(tcx: &ctxt, count_expr: &ast::Expr) -> usize {
     match const_eval::eval_const_expr_partial(tcx, count_expr, Some(tcx.types.usize)) {

src/librustc_trans/trans/base.rs

@@ -560,7 +560,7 @@ pub fn compare_scalar_types<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
                 _ => bcx.sess().bug("compare_scalar_types: must be a comparison operator")
             }
         }
-        ty::ty_bool | ty::ty_uint(_) | ty::ty_char => {
+        ty::ty_bare_fn(..) | ty::ty_bool | ty::ty_uint(_) | ty::ty_char => {
             ICmp(bcx, bin_op_to_icmp_predicate(bcx.ccx(), op, false), lhs, rhs, debug_loc)
         }
         ty::ty_ptr(mt) if common::type_is_sized(bcx.tcx(), mt.ty) => {

src/librustc_trans/trans/consts.rs

@@ -351,7 +351,14 @@ pub fn const_expr<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
 fn const_expr_unadjusted<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
                                    e: &ast::Expr,
                                    ety: Ty<'tcx>,
-                                   param_substs: &'tcx Substs<'tcx>) -> ValueRef {
+                                   param_substs: &'tcx Substs<'tcx>)
+                                   -> ValueRef
+{
+    debug!("const_expr_unadjusted(e={}, ety={}, param_substs={})",
+           e.repr(cx.tcx()),
+           ety.repr(cx.tcx()),
+           param_substs.repr(cx.tcx()));
+
     let map_list = |exprs: &[P<ast::Expr>]| {
         exprs.iter().map(|e| const_expr(cx, &**e, param_substs).0)
              .fold(Vec::new(), |mut l, val| { l.push(val); l })
@@ -366,6 +373,9 @@ fn const_expr_unadjusted<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
             /* Neither type is bottom, and we expect them to be unified
              * already, so the following is safe. */
             let (te1, ty) = const_expr(cx, &**e1, param_substs);
+            debug!("const_expr_unadjusted: te1={}, ty={}",
+                   cx.tn().val_to_string(te1),
+                   ty.repr(cx.tcx()));
             let is_simd = ty::type_is_simd(cx.tcx(), ty);
             let intype = if is_simd {
                 ty::simd_type(cx.tcx(), ty)

src/librustc_trans/trans/expr.rs

@@ -2384,6 +2384,7 @@ fn deref_once<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
     }
 }
 
+#[derive(Debug)]
 enum OverflowOp {
     Add,
     Sub,
@@ -2413,6 +2414,7 @@ enum OverflowCodegen {
 
 enum OverflowOpViaInputCheck { Shl, Shr, }
 
+#[derive(Debug)]
 enum OverflowOpViaIntrinsic { Add, Sub, Mul, }
 
 impl OverflowOpViaIntrinsic {
@@ -2437,7 +2439,8 @@ impl OverflowOpViaIntrinsic {
                 _ => panic!("unsupported target word size")
             },
             ref t @ ty_uint(_) | ref t @ ty_int(_) => t.clone(),
-            _ => panic!("tried to get overflow intrinsic for non-int type")
+            _ => panic!("tried to get overflow intrinsic for {:?} applied to non-int type",
+                        *self)
         };
 
         match *self {

src/librustc_typeck/check/callee.rs

@@ -9,7 +9,6 @@
 // except according to those terms.
 
 use super::autoderef;
-use super::AutorefArgs;
 use super::check_argument_types;
 use super::check_expr;
 use super::check_method_argument_types;
@@ -258,7 +257,6 @@ fn confirm_builtin_call<'a,'tcx>(fcx: &FnCtxt<'a,'tcx>,
                          &fn_sig.inputs,
                          &expected_arg_tys[..],
                          arg_exprs,
-                         AutorefArgs::No,
                          fn_sig.variadic,
                          TupleArgumentsFlag::DontTupleArguments);
 
@@ -288,7 +286,6 @@ fn confirm_deferred_closure_call<'a,'tcx>(fcx: &FnCtxt<'a,'tcx>,
                          &*fn_sig.inputs,
                          &*expected_arg_tys,
                          arg_exprs,
-                         AutorefArgs::No,
                          fn_sig.variadic,
                          TupleArgumentsFlag::TupleArguments);
 
@@ -308,7 +305,6 @@ fn confirm_overloaded_call<'a,'tcx>(fcx: &FnCtxt<'a, 'tcx>,
                                     method_callee.ty,
                                     callee_expr,
                                     arg_exprs,
-                                    AutorefArgs::No,
                                     TupleArgumentsFlag::TupleArguments,
                                     expected);
     write_call(fcx, call_expr, output_type);