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rustc: don't trip an assertion for enums with present but uninhabited variants. #50735

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May 14, 2018
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rustc: don't trip an assertion for enums with present but uninhabited variants. #50735

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5 changes: 5 additions & 0 deletions src/librustc/ty/layout.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -888,6 +888,11 @@ impl<'a, 'tcx> LayoutCx<'tcx, TyCtxt<'a, 'tcx, 'tcx>> {
if x < min { min = x; }
if x > max { max = x; }
}
// We might have no inhabited variants, so pretend there's at least one.
if (min, max) == (i128::max_value(), i128::min_value()) {
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Just to make sure, is (min, max) = max(), min() correct?

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Jup. These are the initial values for both, so that means the loop was empty or all variants uninhabited

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(and the loop can't be empty, thanks to a condition much earlier)

min = 0;
max = 0;
}
assert!(min <= max, "discriminant range is {}...{}", min, max);
let (min_ity, signed) = Integer::repr_discr(tcx, ty, &def.repr, min, max);

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15 changes: 15 additions & 0 deletions src/test/run-pass/issue-50731.rs
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@@ -0,0 +1,15 @@
// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

enum Void {}
fn foo(_: Result<(Void, u32), (Void, String)>) {}
fn main() {
let _: fn(_) = foo;
}