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Extend Infer ty for binary operators #107567

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Extend Infer ty for binary operators #107567

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18 changes: 2 additions & 16 deletions compiler/rustc_const_eval/src/transform/validate.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@ use rustc_middle::mir::{
traversal, AggregateKind, BasicBlock, BinOp, Body, BorrowKind, CastKind, CopyNonOverlapping,
Local, Location, MirPass, MirPhase, NonDivergingIntrinsic, Operand, Place, PlaceElem, PlaceRef,
ProjectionElem, RetagKind, RuntimePhase, Rvalue, SourceScope, Statement, StatementKind,
Terminator, TerminatorKind, UnOp, START_BLOCK,
Terminator, TerminatorKind, START_BLOCK,
};
use rustc_middle::ty::{self, InstanceDef, ParamEnv, Ty, TyCtxt, TypeVisitable};
use rustc_mir_dataflow::impls::MaybeStorageLive;
Expand Down Expand Up @@ -573,21 +573,7 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
_ => self.fail(location, format!("There is no checked version of {:?}", op)),
}
}
Rvalue::UnaryOp(op, operand) => {
let a = operand.ty(&self.body.local_decls, self.tcx);
match op {
UnOp::Neg => {
check_kinds!(a, "Cannot negate type {:?}", ty::Int(..) | ty::Float(..))
}
UnOp::Not => {
check_kinds!(
a,
"Cannot binary not type {:?}",
ty::Int(..) | ty::Uint(..) | ty::Bool
);
}
}
}
Rvalue::UnaryOp(..) => {}
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This validation should not be removed without at least a valid explanation for why it's not necessary anymore 😓

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cc @JakobDegen who added this validation

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It's too late last night, this should be a Draft.
I just found more document for this validations, 6343691

Rvalue::ShallowInitBox(operand, _) => {
let a = operand.ty(&self.body.local_decls, self.tcx);
check_kinds!(a, "Cannot shallow init type {:?}", ty::RawPtr(..));
Expand Down
7 changes: 7 additions & 0 deletions compiler/rustc_hir_typeck/src/expr.rs
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Expand Up @@ -383,6 +383,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
let mut oprnd_t = self.check_expr_with_expectation(&oprnd, expected_inner);

if !oprnd_t.references_error() {
match (unop, oprnd_t.kind()) {
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@compiler-errors compiler-errors Feb 1, 2023 •
edited
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This inference strategy is incorrect. There's no guarantee that the input and output type of Neg or Not are related, and this causes an ICE in the compiler:

#[derive(Copy, Clone, Default)]
struct A;

struct B;

impl std::ops::Not for A {
    type Output = B;

    fn not(self) -> B { B }
}

fn main() {
    let x = Default::default();
    let y: A = !x;
}

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In this example x is constrained to be A because of the inference, but that would imply that y is type B, not A.

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make sense 👍
this is a trivial difference here, binary op is more eager, so unary will infer type error.

pub fn bools(x: &Vec<bool>) {
    let binary = |i, a: &Vec<bool>| {
        a[i] && a[i+1] // ok
    };

    let unary = |i, a: &Vec<bool>| {
        !a[i] // cannot infer type
    };

    binary(0, x);
    unary(0, x);
}

Seems we can not find proper fix for this scenario?

(hir::UnOp::Not | hir::UnOp::Neg, ty::Infer(ty::TyVar(_))) => {
return oprnd_t;
}
_ => {}
}

oprnd_t = self.structurally_resolved_type(expr.span, oprnd_t);
match unop {
hir::UnOp::Deref => {
Expand Down
60 changes: 60 additions & 0 deletions tests/ui/inference/issue-106138.rs
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@@ -0,0 +1,60 @@
// check-pass

fn myfunction(x: &Vec<bool>, y: &Vec<i32> ) {
let one = |i, a: &Vec<bool>| {
a[i] // ok
};

let two = |i, a: &Vec<bool>| {
!a[i] // cannot infer type
};

let three = |i, b: &Vec<i32>| {
-b[i] // ok
};

let r = one(0, x);
assert_eq!(r, x[0]);
let r = two(0, x);
assert_eq!(r, !x[0]);
let r = three(0, y);
assert_eq!(r, -y[0]);
}

fn bools(x: &Vec<bool>) {
let binary = |i, a: &Vec<bool>| {
a[i] && a[i+1] // ok
};

let unary = |i, a: &Vec<bool>| {
!a[i] // cannot infer type
};

let r = binary(0, x);
assert_eq!(r, x[0] && x[1]);

let r = unary(0, x);
assert_eq!(r, !x[0]);
}

fn ints(x: &Vec<i32>) {
let binary = |i, a: &Vec<i32>| {
a[i] + a[i+1] // ok
};
let unary = |i, a: &Vec<i32>| {
-a[i] // cannot infer type
};

let r = binary(0, x);
assert_eq!(r, x[0] + x[1]);
let r = unary(0, x);
assert_eq!(r, -x[0]);
}

fn main() {
let x = vec![true, false];
let y = vec![1, 2, 3];
myfunction(&x, &y);
bools(&x);
ints(&y);
}