Trait collections::fmt::Debug 1.0.0
[−]
[src]
pub trait Debug {
fn fmt(&self, &mut Formatter) -> Result<(), Error>;
}Format trait for the ? character.
Debug should format the output in a programmer-facing, debugging context.
Generally speaking, you should just derive a Debug implementation.
When used with the alternate format specifier #?, the output is pretty-printed.
For more information on formatters, see the module-level documentation.
This trait can be used with #[derive] if all fields implement Debug. When
derived for structs, it will use the name of the struct, then {, then a
comma-separated list of each field's name and Debug value, then }. For
enums, it will use the name of the variant and, if applicable, (, then the
Debug values of the fields, then ).
Examples
Deriving an implementation:
#[derive(Debug)] struct Point { x: i32, y: i32, } let origin = Point { x: 0, y: 0 }; println!("The origin is: {:?}", origin);Run
Manually implementing:
use std::fmt; struct Point { x: i32, y: i32, } impl fmt::Debug for Point { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { write!(f, "Point {{ x: {}, y: {} }}", self.x, self.y) } } let origin = Point { x: 0, y: 0 }; println!("The origin is: {:?}", origin);Run
This outputs:
The origin is: Point { x: 0, y: 0 }
There are a number of debug_* methods on Formatter to help you with manual
implementations, such as debug_struct.
Debug implementations using either derive or the debug builder API
on Formatter support pretty printing using the alternate flag: {:#?}.
Pretty printing with #?:
#[derive(Debug)] struct Point { x: i32, y: i32, } let origin = Point { x: 0, y: 0 }; println!("The origin is: {:#?}", origin);Run
This outputs:
The origin is: Point {
x: 0,
y: 0
}
Required Methods
Implementors
impl<T> Debug for Box<T> where T: Debug + ?Sizedimpl<T> Debug for alloc::arc::Weak<T> where T: Debug + ?Sizedimpl<T> Debug for Arc<T> where T: Debug + ?Sizedimpl<T> Debug for Rc<T> where T: Debug + ?Sizedimpl<T> Debug for alloc::rc::Weak<T> where T: Debug + ?Sizedimpl Debug for DecodeUtf16Errorimpl<T> Debug for Wrapping<T> where T: Debugimpl<T> Debug for Discriminant<T>impl Debug for RangeFullimpl<Idx> Debug for Range<Idx> where Idx: Debugimpl<Idx> Debug for RangeFrom<Idx> where Idx: Debugimpl<Idx> Debug for RangeTo<Idx> where Idx: Debugimpl<Idx> Debug for RangeInclusive<Idx> where Idx: Debugimpl<Idx> Debug for RangeToInclusive<Idx> where Idx: Debugimpl Debug for core::any::Any + 'staticimpl Debug for core::any::Any + 'static + Sendimpl Debug for AtomicBoolimpl<T> Debug for AtomicPtr<T>impl Debug for BorrowErrorimpl Debug for BorrowMutErrorimpl<T> Debug for Empty<T>impl<I, F> Debug for Map<I, F> where I: Debugimpl<I, P> Debug for Filter<I, P> where I: Debugimpl<I, F> Debug for FilterMap<I, F> where I: Debugimpl<I, P> Debug for SkipWhile<I, P> where I: Debugimpl<I, P> Debug for TakeWhile<I, P> where I: Debugimpl<I, St, F> Debug for Scan<I, St, F> where I: Debug, St: Debugimpl<I, U, F> Debug for FlatMap<I, U, F> where I: Debug,
U: IntoIterator,
U::IntoIter: Debugimpl<I, F> Debug for Inspect<I, F> where I: Debugimpl<'a, T> Debug for collections::slice::Iter<'a, T> where T: 'a + Debugimpl<'a, T> Debug for collections::slice::IterMut<'a, T> where T: 'a + Debugimpl<'a, T, P> Debug for collections::slice::Split<'a, T, P> where P: FnMut(&T) -> bool,
T: 'a + Debugimpl<'a, T, P> Debug for SplitMut<'a, T, P> where P: FnMut(&T) -> bool,
T: 'a + Debugimpl<'a, T, P> Debug for collections::slice::SplitN<'a, T, P> where P: FnMut(&T) -> bool,
T: 'a + Debugimpl<'a, T, P> Debug for collections::slice::RSplitN<'a, T, P> where P: FnMut(&T) -> bool,
T: 'a + Debugimpl<'a, T, P> Debug for SplitNMut<'a, T, P> where P: FnMut(&T) -> bool,
T: 'a + Debugimpl<'a, T, P> Debug for RSplitNMut<'a, T, P> where P: FnMut(&T) -> bool,
T: 'a + Debugimpl<'a, F> Debug for CharPredicateSearcher<'a, F> where F: FnMut(char) -> boolimpl<H> Debug for BuildHasherDefault<H>impl<'a> Debug for Arguments<'a>impl Debug for !impl Debug for boolimpl Debug for strimpl Debug for charimpl<T> Debug for *const T where T: ?Sizedimpl<T> Debug for *mut T where T: ?Sizedimpl<T> Debug for [T] where T: Debugimpl Debug for ()impl<T> Debug for PhantomData<T> where T: ?Sizedimpl<T> Debug for Cell<T> where T: Copy + Debugimpl<T> Debug for RefCell<T> where T: Debug + ?Sizedimpl<'b, T> Debug for Ref<'b, T> where T: Debug + ?Sizedimpl<'b, T> Debug for RefMut<'b, T> where T: Debug + ?Sizedimpl<T> Debug for UnsafeCell<T> where T: Debug + ?Sizedimpl Debug for ParseFloatErrorimpl Debug for FpCategoryimpl Debug for TryFromIntErrorimpl Debug for ParseIntErrorimpl<T> Debug for NonZero<T> where T: Zeroable + Debugimpl<Ret> Debug for fn() -> Retimpl<Ret> Debug for extern fn() -> Retimpl<Ret> Debug for unsafe fn() -> Retimpl<Ret> Debug for unsafe extern fn() -> Retimpl<Ret, A> Debug for fn(A) -> Retimpl<Ret, A> Debug for extern fn(A) -> Retimpl<Ret, A> Debug for extern fn(A, ...) -> Retimpl<Ret, A> Debug for unsafe fn(A) -> Retimpl<Ret, A> Debug for unsafe extern fn(A) -> Retimpl<Ret, A> Debug for unsafe extern fn(A, ...) -> Retimpl<Ret, A, B> Debug for fn(A, B) -> Retimpl<Ret, A, B> Debug for extern fn(A, B) -> Retimpl<Ret, A, B> Debug for extern fn(A, B, ...) -> Retimpl<Ret, A, B> Debug for unsafe fn(A, B) -> Retimpl<Ret, A, B> Debug for unsafe extern fn(A, B) -> Retimpl<Ret, A, B> Debug for unsafe extern fn(A, B, ...) -> Retimpl<Ret, A, B, C> Debug for fn(A, B, C) -> Retimpl<Ret, A, B, C> Debug for extern fn(A, B, C) -> Retimpl<Ret, A, B, C> Debug for extern fn(A, B, C, ...) -> Retimpl<Ret, A, B, C> Debug for unsafe fn(A, B, C) -> Retimpl<Ret, A, B, C> Debug for unsafe extern fn(A, B, C) -> Retimpl<Ret, A, B, C> Debug for unsafe extern fn(A, B, C, ...) -> Retimpl<Ret, A, B, C, D> Debug for fn(A, B, C, D) -> Retimpl<Ret, A, B, C, D> Debug for extern fn(A, B, C, D) -> Retimpl<Ret, A, B, C, D> Debug for extern fn(A, B, C, D, ...) -> Retimpl<Ret, A, B, C, D> Debug for unsafe fn(A, B, C, D) -> Retimpl<Ret, A, B, C, D> Debug for unsafe extern fn(A, B, C, D) -> Retimpl<Ret, A, B, C, D> Debug for unsafe extern fn(A, B, C, D, ...) -> Retimpl<Ret, A, B, C, D, E> Debug for fn(A, B, C, D, E) -> Retimpl<Ret, A, B, C, D, E> Debug for extern fn(A, B, C, D, E) -> Retimpl<Ret, A, B, C, D, E> Debug for extern fn(A, B, C, D, E, ...) -> Retimpl<Ret, A, B, C, D, E> Debug for unsafe fn(A, B, C, D, E) -> Retimpl<Ret, A, B, C, D, E> Debug for unsafe extern fn(A, B, C, D, E) -> Retimpl<Ret, A, B, C, D, E> Debug for unsafe extern fn(A, B, C, D, E, ...) -> Retimpl<Ret, A, B, C, D, E, F> Debug for fn(A, B, C, D, E, F) -> Retimpl<Ret, A, B, C, D, E, F> Debug for extern fn(A, B, C, D, E, F) -> Retimpl<Ret, A, B, C, D, E, F> Debug for extern fn(A, B, C, D, E, F, ...) -> Retimpl<Ret, A, B, C, D, E, F> Debug for unsafe fn(A, B, C, D, E, F) -> Retimpl<Ret, A, B, C, D, E, F> Debug for unsafe extern fn(A, B, C, D, E, F) -> Retimpl<Ret, A, B, C, D, E, F> Debug for unsafe extern fn(A, B, C, D, E, F, ...) -> Retimpl<Ret, A, B, C, D, E, F, G> Debug for fn(A, B, C, D, E, F, G) -> Retimpl<Ret, A, B, C, D, E, F, G> Debug for extern fn(A, B, C, D, E, F, G) -> Retimpl<Ret, A, B, C, D, E, F, G> Debug for extern fn(A, B, C, D, E, F, G, ...) -> Retimpl<Ret, A, B, C, D, E, F, G> Debug for unsafe fn(A, B, C, D, E, F, G) -> Retimpl<Ret, A, B, C, D, E, F, G> Debug for unsafe extern fn(A, B, C, D, E, F, G) -> Retimpl<Ret, A, B, C, D, E, F, G> Debug for unsafe extern fn(A, B, C, D, E, F, G, ...) -> Retimpl<Ret, A, B, C, D, E, F, G, H> Debug for fn(A, B, C, D, E, F, G, H) -> Retimpl<Ret, A, B, C, D, E, F, G, H> Debug for extern fn(A, B, C, D, E, F, G, H) -> Retimpl<Ret, A, B, C, D, E, F, G, H> Debug for extern fn(A, B, C, D, E, F, G, H, ...) -> Retimpl<Ret, A, B, C, D, E, F, G, H> Debug for unsafe fn(A, B, C, D, E, F, G, H) -> Retimpl<Ret, A, B, C, D, E, F, G, H> Debug for unsafe extern fn(A, B, C, D, E, F, G, H) -> Retimpl<Ret, A, B, C, D, E, F, G, H> Debug for unsafe extern fn(A, B, C, D, E, F, G, H, ...) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I> Debug for fn(A, B, C, D, E, F, G, H, I) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I> Debug for extern fn(A, B, C, D, E, F, G, H, I) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I> Debug for extern fn(A, B, C, D, E, F, G, H, I, ...) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I> Debug for unsafe fn(A, B, C, D, E, F, G, H, I) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I> Debug for unsafe extern fn(A, B, C, D, E, F, G, H, I) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I> Debug for unsafe extern fn(A, B, C, D, E, F, G, H, I, ...) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J> Debug for fn(A, B, C, D, E, F, G, H, I, J) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J> Debug for extern fn(A, B, C, D, E, F, G, H, I, J) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J> Debug for extern fn(A, B, C, D, E, F, G, H, I, J, ...) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J> Debug for unsafe fn(A, B, C, D, E, F, G, H, I, J) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J> Debug for unsafe extern fn(A, B, C, D, E, F, G, H, I, J) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J> Debug for unsafe extern fn(A, B, C, D, E, F, G, H, I, J, ...) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K> Debug for fn(A, B, C, D, E, F, G, H, I, J, K) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K> Debug for extern fn(A, B, C, D, E, F, G, H, I, J, K) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K> Debug for extern fn(A, B, C, D, E, F, G, H, I, J, K, ...) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K> Debug for unsafe fn(A, B, C, D, E, F, G, H, I, J, K) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K> Debug for unsafe extern fn(A, B, C, D, E, F, G, H, I, J, K) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K> Debug for unsafe extern fn(A, B, C, D, E, F, G, H, I, J, K, ...) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Debug for fn(A, B, C, D, E, F, G, H, I, J, K, L) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Debug for extern fn(A, B, C, D, E, F, G, H, I, J, K, L) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Debug for extern fn(A, B, C, D, E, F, G, H, I, J, K, L, ...) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Debug for unsafe fn(A, B, C, D, E, F, G, H, I, J, K, L) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Debug for unsafe extern fn(A, B, C, D, E, F, G, H, I, J, K, L) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Debug for unsafe extern fn(A, B, C, D, E, F, G, H, I, J, K, L, ...) -> Retimpl Debug for core::cmp::Orderingimpl Debug for TypeIdimpl<T> Debug for [T; 0] where T: Debugimpl<T> Debug for [T; 1] where T: Debugimpl<T> Debug for [T; 2] where T: Debugimpl<T> Debug for [T; 3] where T: Debugimpl<T> Debug for [T; 4] where T: Debugimpl<T> Debug for [T; 5] where T: Debugimpl<T> Debug for [T; 6] where T: Debugimpl<T> Debug for [T; 7] where T: Debugimpl<T> Debug for [T; 8] where T: Debugimpl<T> Debug for [T; 9] where T: Debugimpl<T> Debug for [T; 10] where T: Debugimpl<T> Debug for [T; 11] where T: Debugimpl<T> Debug for [T; 12] where T: Debugimpl<T> Debug for [T; 13] where T: Debugimpl<T> Debug for [T; 14] where T: Debugimpl<T> Debug for [T; 15] where T: Debugimpl<T> Debug for [T; 16] where T: Debugimpl<T> Debug for [T; 17] where T: Debugimpl<T> Debug for [T; 18] where T: Debugimpl<T> Debug for [T; 19] where T: Debugimpl<T> Debug for [T; 20] where T: Debugimpl<T> Debug for [T; 21] where T: Debugimpl<T> Debug for [T; 22] where T: Debugimpl<T> Debug for [T; 23] where T: Debugimpl<T> Debug for [T; 24] where T: Debugimpl<T> Debug for [T; 25] where T: Debugimpl<T> Debug for [T; 26] where T: Debugimpl<T> Debug for [T; 27] where T: Debugimpl<T> Debug for [T; 28] where T: Debugimpl<T> Debug for [T; 29] where T: Debugimpl<T> Debug for [T; 30] where T: Debugimpl<T> Debug for [T; 31] where T: Debugimpl<T> Debug for [T; 32] where T: Debugimpl Debug for core::sync::atomic::Orderingimpl Debug for AtomicI8impl Debug for AtomicU8impl Debug for AtomicI16impl Debug for AtomicU16impl Debug for AtomicI32impl Debug for AtomicU32impl Debug for AtomicI64impl Debug for AtomicU64impl Debug for AtomicIsizeimpl Debug for AtomicUsizeimpl Debug for BorrowStateimpl Debug for CharTryFromErrorimpl Debug for EscapeUnicodeimpl Debug for EscapeDefaultimpl Debug for EscapeDebugimpl<I> Debug for DecodeUtf8<I> where I: Iterator<Item=u8> + Debugimpl Debug for InvalidSequenceimpl<A, R> Debug for StepBy<A, R> where A: Debug, R: Debugimpl<A> Debug for Repeat<A> where A: Debugimpl<T> Debug for Once<T> where T: Debugimpl<T> Debug for Rev<T> where T: Debugimpl<I> Debug for Cloned<I> where I: Debugimpl<I> Debug for Cycle<I> where I: Debugimpl<A, B> Debug for Chain<A, B> where A: Debug, B: Debugimpl<A, B> Debug for Zip<A, B> where A: Debug, B: Debugimpl<I> Debug for Enumerate<I> where I: Debugimpl<I> Debug for Peekable<I> where I: Iterator + Debug, I::Item: Debugimpl<I> Debug for Skip<I> where I: Debugimpl<I> Debug for Take<I> where I: Debugimpl<I> Debug for Fuse<I> where I: Debugimpl<T> Debug for Option<T> where T: Debugimpl<'a, A> Debug for core::option::Iter<'a, A> where A: 'a + Debugimpl<'a, A> Debug for core::option::IterMut<'a, A> where A: 'a + Debugimpl<A> Debug for core::option::IntoIter<A> where A: Debugimpl<T, E> Debug for Result<T, E> where E: Debug, T: Debugimpl<'a, T> Debug for core::result::Iter<'a, T> where T: 'a + Debugimpl<'a, T> Debug for core::result::IterMut<'a, T> where T: 'a + Debugimpl<T> Debug for core::result::IntoIter<T> where T: Debugimpl<'a, T> Debug for Windows<'a, T> where T: 'a + Debugimpl<'a, T> Debug for Chunks<'a, T> where T: 'a + Debugimpl<'a, T> Debug for ChunksMut<'a, T> where T: 'a + Debugimpl Debug for SearchStepimpl<'a> Debug for CharSearcher<'a>impl<'a, 'b> Debug for CharSliceSearcher<'a, 'b>impl<'a, 'b> Debug for StrSearcher<'a, 'b>impl Debug for ParseBoolErrorimpl Debug for Utf8Errorimpl<'a> Debug for Chars<'a>impl<'a> Debug for CharIndices<'a>impl<'a> Debug for Bytes<'a>impl<'a, P> Debug for collections::str::Split<'a, P> where P: Pattern<'a>, P::Searcher: Debugimpl<'a, P> Debug for RSplit<'a, P> where P: Pattern<'a>, P::Searcher: Debugimpl<'a, P> Debug for SplitTerminator<'a, P> where P: Pattern<'a>,
P::Searcher: Debugimpl<'a, P> Debug for RSplitTerminator<'a, P> where P: Pattern<'a>,
P::Searcher: Debugimpl<'a, P> Debug for collections::str::SplitN<'a, P> where P: Pattern<'a>, P::Searcher: Debugimpl<'a, P> Debug for collections::str::RSplitN<'a, P> where P: Pattern<'a>, P::Searcher: Debugimpl<'a, P> Debug for MatchIndices<'a, P> where P: Pattern<'a>,
P::Searcher: Debugimpl<'a, P> Debug for RMatchIndices<'a, P> where P: Pattern<'a>,
P::Searcher: Debugimpl<'a, P> Debug for Matches<'a, P> where P: Pattern<'a>, P::Searcher: Debugimpl<'a, P> Debug for RMatches<'a, P> where P: Pattern<'a>, P::Searcher: Debugimpl<'a> Debug for Lines<'a>impl<'a> Debug for LinesAny<'a>impl Debug for SipHasher13impl Debug for SipHasher24impl Debug for SipHasherimpl Debug for Alignmentimpl Debug for isizeimpl Debug for usizeimpl Debug for i8impl Debug for u8impl Debug for i16impl Debug for u16impl Debug for i32impl Debug for u32impl Debug for i64impl Debug for u64impl Debug for i128impl Debug for u128impl Debug for Errorimpl<'a, T> Debug for &'a T where T: Debug + ?Sizedimpl<'a, T> Debug for &'a mut T where T: Debug + ?Sizedimpl Debug for f32impl Debug for f64impl<T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11> Debug for (T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11) where T0: Debug,
T1: Debug,
T10: Debug,
T11: Debug,
T2: Debug,
T3: Debug,
T4: Debug,
T5: Debug,
T6: Debug,
T7: Debug,
T8: Debug,
T9: Debugimpl<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11> Debug for (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11) where T1: Debug,
T10: Debug,
T11: Debug,
T2: Debug,
T3: Debug,
T4: Debug,
T5: Debug,
T6: Debug,
T7: Debug,
T8: Debug,
T9: Debugimpl<T2, T3, T4, T5, T6, T7, T8, T9, T10, T11> Debug for (T2, T3, T4, T5, T6, T7, T8, T9, T10, T11) where T10: Debug,
T11: Debug,
T2: Debug,
T3: Debug,
T4: Debug,
T5: Debug,
T6: Debug,
T7: Debug,
T8: Debug,
T9: Debugimpl<T3, T4, T5, T6, T7, T8, T9, T10, T11> Debug for (T3, T4, T5, T6, T7, T8, T9, T10, T11) where T10: Debug,
T11: Debug,
T3: Debug,
T4: Debug,
T5: Debug,
T6: Debug,
T7: Debug,
T8: Debug,
T9: Debugimpl<T4, T5, T6, T7, T8, T9, T10, T11> Debug for (T4, T5, T6, T7, T8, T9, T10, T11) where T10: Debug,
T11: Debug,
T4: Debug,
T5: Debug,
T6: Debug,
T7: Debug,
T8: Debug,
T9: Debugimpl<T5, T6, T7, T8, T9, T10, T11> Debug for (T5, T6, T7, T8, T9, T10, T11) where T10: Debug,
T11: Debug,
T5: Debug,
T6: Debug,
T7: Debug,
T8: Debug,
T9: Debugimpl<T6, T7, T8, T9, T10, T11> Debug for (T6, T7, T8, T9, T10, T11) where T10: Debug,
T11: Debug,
T6: Debug,
T7: Debug,
T8: Debug,
T9: Debugimpl<T7, T8, T9, T10, T11> Debug for (T7, T8, T9, T10, T11) where T10: Debug,
T11: Debug,
T7: Debug,
T8: Debug,
T9: Debugimpl<T8, T9, T10, T11> Debug for (T8, T9, T10, T11) where T10: Debug,
T11: Debug,
T8: Debug,
T9: Debugimpl<T9, T10, T11> Debug for (T9, T10, T11) where T10: Debug,
T11: Debug,
T9: Debugimpl<T10, T11> Debug for (T10, T11) where T10: Debug, T11: Debugimpl<T11> Debug for (T11,) where T11: Debugimpl<T: Debug + Ord> Debug for BinaryHeap<T>impl<'a, K: 'a + Debug + Ord, V: 'a + Debug> Debug for Entry<'a, K, V>impl<'a, K: 'a + Debug + Ord, V: 'a> Debug for VacantEntry<'a, K, V>impl<'a, K: 'a + Debug + Ord, V: 'a + Debug> Debug for OccupiedEntry<'a, K, V>impl<K: Debug, V: Debug> Debug for BTreeMap<K, V>impl<T: Debug> Debug for BTreeSet<T>impl<'a, B: ?Sized> Debug for Cow<'a, B> where B: Debug + ToOwned,
B::Owned: Debugimpl<E: CLike + Debug> Debug for EnumSet<E>impl<T: Debug> Debug for LinkedList<T>impl Debug for FromUtf8Errorimpl Debug for FromUtf16Errorimpl Debug for Stringimpl Debug for ParseErrorimpl<T: Debug> Debug for Vec<T>impl<T: Debug> Debug for collections::vec::IntoIter<T>impl<T: Debug> Debug for VecDeque<T>impl<T: Debug> Debug for Bound<T>