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Rollup merge of #61702 - RalfJung:const-enum-cast, r=oli-obk

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test more variants of enum-int-casting

As I learned in https://github.com/rust-lang/rust/pull/61673#issuecomment-500213506, there is a code path we are not testing yet. Looks like enum-int-casting with and without an intermediate let-binding is totally different.

EDIT: The reason for this is to get rid of the cycle in definitions such as:
```rust
enum Foo {
    A = 0,
    B = Foo::A as isize + 2,
}
```
This has historically been supported, so a hack adding special treatment to `Enum::Variant as _` was added to keep supporting it.
This commit is contained in:
Mazdak Farrokhzad 2019-06-17 20:55:55 +02:00 committed by GitHub
commit a2259aae7d
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1 changed files with 11 additions and 2 deletions
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13
src/test/run-pass/consts/const-enum-cast.rs
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@ -1,9 +1,8 @@
// run-pass
#![allow(dead_code)]
#![allow(non_upper_case_globals)]
enum A { A1, A2 }
enum B { B1=0, B2=2 }
enum B { B1=4, B2=2 }
pub fn main () {
static c1: isize = A::A2 as isize;
@ -14,4 +13,14 @@ pub fn main () {
assert_eq!(c2, 2);
assert_eq!(a1, 1);
assert_eq!(a2, 2);
// Turns out that adding a let-binding generates totally different MIR.
static c1_2: isize = { let v = A::A1; v as isize };
static c2_2: isize = { let v = B::B1; v as isize };
let a1_2 = { let v = A::A1; v as isize };
let a2_2 = { let v = B::B1; v as isize };
assert_eq!(c1_2, 0);
assert_eq!(c2_2, 4);
assert_eq!(a1_2, 0);
assert_eq!(a2_2, 4);
}