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[MIR] Mir generation for match statements seems to miss arms with guard clauses #30527

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michaelwoerister opened this issue Dec 22, 2015 · 1 comment
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[MIR] Mir generation for match statements seems to miss arms with guard clauses #30527

michaelwoerister opened this issue Dec 22, 2015 · 1 comment
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A-MIR Area: Mid-level IR (MIR) - https://blog.rust-lang.org/2016/04/19/MIR.html

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@michaelwoerister
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Example:

#![feature(rustc_attrs)]
#[rustc_mir(graphviz="match.dot")]
fn main() {
    let _abc = match Some(101i8) {
        Some(xyz) if xyz > 100 => xyz,
        Some(_) => -1,
        None => -2
    };
}

The resulting MIR does not contain the Some(xyz) arm: http://i.imgur.com/EF489mM.png
@michaelwoerister michaelwoerister added the A-MIR Area: Mid-level IR (MIR) - https://blog.rust-lang.org/2016/04/19/MIR.html label Dec 22, 2015
@nikomatsakis
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cc me

@luqmana luqmana mentioned this issue Dec 25, 2015
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bors added a commit that referenced this issue Jan 4, 2016
@bors
Auto merge of #30553 - luqmana:mir-match-arm-guards, r=nikomatsakis
b622891 
Fixes #30527.

```Rust

fn main() {
    let _abc = match Some(101i8) {
        Some(xyz) if xyz > 100 => xyz,
        Some(_) => -1,
        None => -2
    };
}
```

Resulting MIR now includes the `Some(xyz)` arm, guard and all:
![match.dot](https://cloud.githubusercontent.com/assets/287063/11999413/066f7610-aa8b-11e5-927b-24215af57fc4.png)

~~Not quite sure how to write a test for this.~~ Thinking too hard, just tested the end result.

r? @nikomatsakis
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A-MIR Area: Mid-level IR (MIR) - https://blog.rust-lang.org/2016/04/19/MIR.html
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@nikomatsakis @michaelwoerister