diff options
Diffstat (limited to 'tests/ui/destructuring-assignment/warn-unused-duplication.rs')
-rw-r--r-- | tests/ui/destructuring-assignment/warn-unused-duplication.rs | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/tests/ui/destructuring-assignment/warn-unused-duplication.rs b/tests/ui/destructuring-assignment/warn-unused-duplication.rs new file mode 100644 index 000000000..390f44b8a --- /dev/null +++ b/tests/ui/destructuring-assignment/warn-unused-duplication.rs @@ -0,0 +1,21 @@ +// run-pass + +#![warn(unused_assignments)] + +fn main() { + let mut a; + // Assignment occurs left-to-right. + // However, we emit warnings when this happens, so it is clear that this is happening. + (a, a) = (0, 1); //~ WARN value assigned to `a` is never read + assert_eq!(a, 1); + + // We can't always tell when a variable is being assigned to twice, which is why we don't try + // to emit an error, which would be fallible. + let mut x = 1; + (*foo(&mut x), *foo(&mut x)) = (5, 6); + assert_eq!(x, 6); +} + +fn foo<'a>(x: &'a mut u32) -> &'a mut u32 { + x +} |