From 1376c5a617be5c25655d0d7cb63e3beaa5a6e026 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 17 Apr 2024 14:20:39 +0200 Subject: Merging upstream version 1.70.0+dfsg1. Signed-off-by: Daniel Baumann --- .../variance-intersection-of-ref-and-opt-ref.rs | 25 ++++++++++++++++++++++ 1 file changed, 25 insertions(+) create mode 100644 tests/ui/variance/variance-intersection-of-ref-and-opt-ref.rs (limited to 'tests/ui/variance/variance-intersection-of-ref-and-opt-ref.rs') diff --git a/tests/ui/variance/variance-intersection-of-ref-and-opt-ref.rs b/tests/ui/variance/variance-intersection-of-ref-and-opt-ref.rs new file mode 100644 index 000000000..74707a98d --- /dev/null +++ b/tests/ui/variance/variance-intersection-of-ref-and-opt-ref.rs @@ -0,0 +1,25 @@ +// run-pass +// Elaborated version of the opening example from RFC 738. This failed +// to compile before variance because invariance of `Option` prevented +// us from approximating the lifetimes of `field1` and `field2` to a +// common intersection. + +#![allow(dead_code)] + +struct List<'l> { + field1: &'l i32, + field2: Option<&'l i32>, +} + +fn foo(field1: &i32, field2: Option<&i32>) -> i32 { + let list = List { field1: field1, field2: field2 }; + *list.field1 + list.field2.cloned().unwrap_or(0) +} + +fn main() { + let x = 22; + let y = Some(3); + let z = None; + assert_eq!(foo(&x, y.as_ref()), 25); + assert_eq!(foo(&x, z.as_ref()), 22); +} -- cgit v1.2.3