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Fix const evaluation ICE in rustdoc #47862

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merged 1 commit into from
Feb 5, 2018
Merged

Fix const evaluation ICE in rustdoc #47862

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11 changes: 9 additions & 2 deletions src/librustdoc/clean/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2447,7 +2447,12 @@ impl Clean<Type> for hir::Ty {
let def_id = cx.tcx.hir.body_owner_def_id(n);
let param_env = cx.tcx.param_env(def_id);
let substs = Substs::identity_for_item(cx.tcx, def_id);
let n = cx.tcx.const_eval(param_env.and((def_id, substs))).unwrap();
let n = cx.tcx.const_eval(param_env.and((def_id, substs))).unwrap_or_else(|_| {
cx.tcx.mk_const(ty::Const {
val: ConstVal::Unevaluated(def_id, substs),
ty: cx.tcx.types.usize
})
});
let n = if let ConstVal::Integral(ConstInt::Usize(n)) = n.val {
n.to_string()
} else if let ConstVal::Unevaluated(def_id, _) = n.val {
Expand Down Expand Up @@ -2577,7 +2582,9 @@ impl<'tcx> Clean<Type> for Ty<'tcx> {
let mut n = cx.tcx.lift(&n).unwrap();
if let ConstVal::Unevaluated(def_id, substs) = n.val {
let param_env = cx.tcx.param_env(def_id);
n = cx.tcx.const_eval(param_env.and((def_id, substs))).unwrap()
if let Ok(new_n) = cx.tcx.const_eval(param_env.and((def_id, substs))) {
n = new_n;
}
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Can you use the same trick in the other function? You just have to do this first, before const_eval:

let n = tcx.mk_const(ty::Const {
    val: ConstVal::Unevaluated(def_id, substs),
    ty: tcx.types.usize
});

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Do you mean instead of const_eval? Otherwise, this new assignement to n will never be used...

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I mean it'd be this in the other place (line 2450) - rewrote it a bit since previous comment:

let n = cx.tcx.const_eval(param_env.and((def_id, substs))).unwrap_or_else(|_| {
    cx.tcx.mk_const(ty::Const {
        val: ConstVal::Unevaluated(def_id, substs),
        ty: cx.tcx.types.usize
    })
});

};
let n = if let ConstVal::Integral(ConstInt::Usize(n)) = n.val {
n.to_string()
Expand Down
22 changes: 22 additions & 0 deletions src/test/rustdoc/const-evalutation-ice.rs
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@@ -0,0 +1,22 @@
// 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.

// Just check if we don't get an ICE for the _S type.

#![feature(const_size_of)]

use std::cell::Cell;
use std::mem;

pub struct S {
s: Cell<usize>
}

pub type _S = [usize; 0 - (mem::size_of::<S>() != 4) as usize];