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Fix auto_ref for fat pointers
Fat pointers aren't immediate, so in a datum, they're not actually
ByValue but ByRef.

Fixes #24589
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dotdash committed May 25, 2015
1 parent 2bc0bf2 commit efd3e75
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Showing 2 changed files with 29 additions and 1 deletion.
4 changes: 3 additions & 1 deletion src/librustc_trans/trans/expr.rs
Expand Up @@ -2180,7 +2180,9 @@ fn auto_ref<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
// Construct the resulting datum, using what was the "by ref"
// ValueRef of type `referent_ty` to be the "by value" ValueRef
// of type `&referent_ty`.
DatumBlock::new(bcx, Datum::new(llref, ptr_ty, RvalueExpr(Rvalue::new(ByValue))))
// Pointers to DST types are non-immediate, and therefore still use ByRef.
let kind = if type_is_sized(bcx.tcx(), referent_ty) { ByValue } else { ByRef };
DatumBlock::new(bcx, Datum::new(llref, ptr_ty, RvalueExpr(Rvalue::new(kind))))
}

fn deref_multiple<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
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26 changes: 26 additions & 0 deletions src/test/run-pass/issue-24589.rs
@@ -0,0 +1,26 @@
// Copyright 2015 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.

pub struct _X([u8]);

impl std::ops::Deref for _X {
type Target = [u8];

fn deref(&self) -> &[u8] {
&self.0
}
}

pub fn _g(x: &_X) -> &[u8] {
x
}

fn main() {
}

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