# Struct rustc_pattern_analysis::lints::PatternColumn

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    pub(crate) struct PatternColumn<'p, 'tcx> {
        patterns: Vec<&'p DeconstructedPat<'p, 'tcx>>,
    }

Expand description

A column of patterns in the matrix, where a column is the intuitive notion of “subpatterns that inspect the same subvalue/place”. This is used to traverse patterns column-by-column for lints. Despite similarities with the algorithm in `crate::usefulness`, this does a different traversal. Notably this is linear in the depth of patterns, whereas `compute_exhaustiveness_and_usefulness` is worst-case exponential (exhaustiveness is NP-complete). The core difference is that we treat sub-columns separately.

This must not contain an or-pattern. `specialize` takes care to expand them.

This is not used in the main algorithm; only in lints.

## Fields§

§`patterns: Vec<&'p DeconstructedPat<'p, 'tcx>>`

## Implementations§

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### impl<'p, 'tcx> PatternColumn<'p, 'tcx>

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#### pub(crate) fn new(arms: &[MatchArm<'p, 'tcx>]) -> Self

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#### fn is_empty(&self) -> bool

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#### fn head_ty(&self) -> Option<RevealedTy<'tcx>>

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#### fn analyze_ctors( &self, pcx: &PlaceCtxt<'_, 'p, RustcMatchCheckCtxt<'p, 'tcx>> ) -> SplitConstructorSet<RustcMatchCheckCtxt<'p, 'tcx>>

Do constructor splitting on the constructors of the column.

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#### fn iter( &self ) -> impl Iterator<Item = &'p DeconstructedPat<'p, 'tcx>> + Captures<'_>

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#### fn specialize( &self, pcx: &PlaceCtxt<'_, 'p, RustcMatchCheckCtxt<'p, 'tcx>>, ctor: &Constructor<'p, 'tcx> ) -> Vec<PatternColumn<'p, 'tcx>>

Does specialization: given a constructor, this takes the patterns from the column that match the constructor, and outputs their fields. This returns one column per field of the constructor. They usually all have the same length (the number of patterns in `self` that matched `ctor`), except that we expand or-patterns which may change the lengths.

## Trait Implementations§

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### impl<'p, 'tcx> Debug for PatternColumn<'p, 'tcx>

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#### fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more

## Auto Trait Implementations§

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### impl<'p, 'tcx> !RefUnwindSafe for PatternColumn<'p, 'tcx>

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### impl<'p, 'tcx> !Send for PatternColumn<'p, 'tcx>

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### impl<'p, 'tcx> !Sync for PatternColumn<'p, 'tcx>

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### impl<'p, 'tcx> Unpin for PatternColumn<'p, 'tcx>

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### impl<'p, 'tcx> !UnwindSafe for PatternColumn<'p, 'tcx>

## Blanket Implementations§

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### impl<T> Any for T
where T: 'static + ?Sized,

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#### fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more
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### impl<T> Borrow<T> for T
where T: ?Sized,

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#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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### impl<T> BorrowMut<T> for T
where T: ?Sized,

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#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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### impl<T> From<T> for T

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#### fn from(t: T) -> T

Returns the argument unchanged.

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### impl<T, U> Into<U> for T
where U: From<T>,

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#### fn into(self) -> U

Calls `U::from(self)`.

That is, this conversion is whatever the implementation of `From<T> for U` chooses to do.

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### impl<T, U> TryFrom<U> for T
where U: Into<T>,

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#### type Error = Infallible

The type returned in the event of a conversion error.
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#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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### impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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#### type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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### impl<'a, T> Captures<'a> for T
where T: ?Sized,

## Layout§

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain `repr(...)` attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 24 bytes