From 64d98f8ee037282c35007b64c2649055c56af1db Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 17 Apr 2024 14:19:03 +0200 Subject: Merging upstream version 1.68.2+dfsg1. Signed-off-by: Daniel Baumann --- tests/ui/specialization/issue-33017.rs | 45 ++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) create mode 100644 tests/ui/specialization/issue-33017.rs (limited to 'tests/ui/specialization/issue-33017.rs') diff --git a/tests/ui/specialization/issue-33017.rs b/tests/ui/specialization/issue-33017.rs new file mode 100644 index 000000000..8dbadf58d --- /dev/null +++ b/tests/ui/specialization/issue-33017.rs @@ -0,0 +1,45 @@ +// Test to ensure that trait bounds are properly +// checked on specializable associated types + +#![allow(incomplete_features)] +#![feature(specialization)] + +trait UncheckedCopy: Sized { + type Output: From + Copy + Into; +} + +impl UncheckedCopy for T { + default type Output = Self; + //~^ ERROR: the trait bound `T: Copy` is not satisfied +} + +fn unchecked_copy(other: &T::Output) -> T { + (*other).into() +} + +fn bug(origin: String) { + // Turn the String into it's Output type... + // Which we can just do by `.into()`, the assoc type states `From`. + let origin_output = origin.into(); + + // Make a copy of String::Output, which is a String... + let mut copy: String = unchecked_copy::(&origin_output); + + // Turn the Output type into a String again, + // Which we can just do by `.into()`, the assoc type states `Into`. + let mut origin: String = origin_output.into(); + + // assert both Strings use the same buffer. + assert_eq!(copy.as_ptr(), origin.as_ptr()); + + // Any use of the copy we made becomes invalid, + drop(origin); + + // OH NO! UB UB UB UB! + copy.push_str(" world!"); + println!("{}", copy); +} + +fn main() { + bug(String::from("hello")); +} -- cgit v1.2.3