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Infinite recursion for enum variant defined in terms of itself #23302

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huonw opened this issue Mar 12, 2015 · 1 comment
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Infinite recursion for enum variant defined in terms of itself #23302

huonw opened this issue Mar 12, 2015 · 1 comment
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I-ICE Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️

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@huonw
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huonw commented Mar 12, 2015 

enum X { A = X::A as isize }

fn main() {}
thread 'rustc' has overflowed its stack
Illegal instruction (core dumped)
@huonw huonw added the I-ICE Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️ label Mar 12, 2015
@andersk andersk mentioned this issue Apr 8, 2015
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@frewsxcv
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Can confirm this is still an issue in Rust 1.0 beta 2

~/Downloads $ rustc test.rs

thread 'rustc' has overflowed its stack
fish: Job 1, 'rustc test.rs ' terminated by signal SIGILL (Illegal instruction)

~/Downloads $ rustc --version
rustc 1.0.0-beta.2 (e9080ec39 2015-04-16) (built 2015-04-16)

quantheory added a commit to quantheory/rust that referenced this issue Jun 23, 2015
@quantheory
Fix issue rust-lang#23302, ICE on recursively defined enum variant di…
faf7302 
…scriminant.
@quantheory quantheory mentioned this issue Jun 23, 2015
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bors added a commit that referenced this issue Jul 9, 2015
@bors
Auto merge of #26515 - quantheory:check_enum_recursion, r=nrc
afe25a2 
Fixes #23302.

Note that there's an odd situation regarding the following, most likely due to some inadequacy in `const_eval`:

```rust
enum Y {
    A = 1usize,
    B,
}
```

In this case, `Y::B as usize` might be considered a constant expression in some cases, but not others.  (See #23513, for a related problem where there is only one variant, with no discriminant, and it doesn't behave nicely as a constant expression either.)

Most of the complexity in this PR is basically future-proofing, to ensure that when `Y::B as usize` is fully made to be a constant expression, it can't be used to set `Y::A`, and thus indirectly itself.
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I-ICE Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️
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