mirror of https://github.com/rust-lang/rust
70 lines
1.7 KiB
Rust
70 lines
1.7 KiB
Rust
//@ run-pass
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//@ check-run-results
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// Tests ensuring that `dbg!(expr)` has the expected run-time behavior.
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// as well as some compile time properties we expect.
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#![allow(dropping_copy_types)]
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#[derive(Copy, Clone, Debug)]
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struct Unit;
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#[derive(Copy, Clone, Debug, PartialEq)]
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struct Point<T> {
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x: T,
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y: T,
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}
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#[derive(Debug, PartialEq)]
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struct NoCopy(usize);
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fn main() {
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let a: Unit = dbg!(Unit);
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let _: Unit = dbg!(a);
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// We can move `a` because it's Copy.
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drop(a);
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// `Point<T>` will be faithfully formatted according to `{:#?}`.
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let a = Point { x: 42, y: 24 };
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let b: Point<u8> = dbg!(Point { x: 42, y: 24 }); // test stringify!(..)
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let c: Point<u8> = dbg!(b);
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// Identity conversion:
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assert_eq!(a, b);
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assert_eq!(a, c);
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// We can move `b` because it's Copy.
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drop(b);
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// Without parameters works as expected.
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let _: () = dbg!();
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// Test that we can borrow and that successive applications is still identity.
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let a = NoCopy(1337);
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let b: &NoCopy = dbg!(dbg!(&a));
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assert_eq!(&a, b);
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// Test involving lifetimes of temporaries:
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fn f<'a>(x: &'a u8) -> &'a u8 { x }
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let a: &u8 = dbg!(f(&42));
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assert_eq!(a, &42);
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// Test side effects:
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let mut foo = 41;
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assert_eq!(7331, dbg!({
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foo += 1;
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eprintln!("before");
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7331
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}));
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assert_eq!(foo, 42);
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// Test trailing comma:
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assert_eq!(("Yeah",), dbg!(("Yeah",)));
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// Test multiple arguments:
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assert_eq!((1u8, 2u32), dbg!(1,
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2));
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// Test multiple arguments + trailing comma:
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assert_eq!((1u8, 2u32, "Yeah"), dbg!(1u8, 2u32,
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"Yeah",));
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}
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