Type Alias rustc_hir_typeck::coercion::DynamicCoerceMany

pub type DynamicCoerceMany<'tcx> = CoerceMany<'tcx, 'tcx, &'tcx Expr<'tcx>>;

The type of a CoerceMany that is storing up the expressions into a buffer. We use this in check/mod.rs for things like break.

Aliased Type

struct DynamicCoerceMany<'tcx> {
    expected_ty: Ty<'tcx>,
    final_ty: Option<Ty<'tcx>>,
    expressions: Expressions<'tcx, 'tcx, &'tcx Expr<'tcx>>,
    pushed: usize,
}

Fields

expected_ty: Ty<'tcx>

final_ty: Option<Ty<'tcx>>

expressions: Expressions<'tcx, 'tcx, &'tcx Expr<'tcx>>

pushed: usize

Implementations

impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E>

pub fn new(expected_ty: Ty<'tcx>) -> Self

The usual case; collect the set of expressions dynamically. If the full set of coercion sites is known before hand, consider with_coercion_sites() instead to avoid allocation.

pub fn with_coercion_sites( expected_ty: Ty<'tcx>, coercion_sites: &'exprs [E] ) -> Self

As an optimization, you can create a CoerceMany with a preexisting slice of expressions. In this case, you are expected to pass each element in the slice to coerce(...) in order. This is used with arrays in particular to avoid needlessly cloning the slice.

fn make( expected_ty: Ty<'tcx>, expressions: Expressions<'tcx, 'exprs, E> ) -> Self

pub fn expected_ty(&self) -> Ty<'tcx>

Returns the “expected type” with which this coercion was constructed. This represents the “downward propagated” type that was given to us at the start of typing whatever construct we are typing (e.g., the match expression).

Typically, this is used as the expected type when type-checking each of the alternative expressions whose types we are trying to merge.

pub fn merged_ty(&self) -> Ty<'tcx>

Returns the current “merged type”, representing our best-guess at the LUB of the expressions we’ve seen so far (if any). This isn’t final until you call self.complete(), which will return the merged type.

pub fn coerce<'a>( &mut self, fcx: &FnCtxt<'a, 'tcx>, cause: &ObligationCause<'tcx>, expression: &'tcx Expr<'tcx>, expression_ty: Ty<'tcx> )

Indicates that the value generated by expression, which is of type expression_ty, is one of the possibilities that we could coerce from. This will record expression, and later calls to coerce may come back and add adjustments and things if necessary.

pub fn coerce_forced_unit<'a>( &mut self, fcx: &FnCtxt<'a, 'tcx>, cause: &ObligationCause<'tcx>, augment_error: impl FnOnce(&mut Diagnostic), label_unit_as_expected: bool )

Indicates that one of the inputs is a “forced unit”. This occurs in a case like if foo { ... };, where the missing else generates a “forced unit”. Another example is a loop { break; }, where the break has no argument expression. We treat these cases slightly differently for error-reporting purposes. Note that these tend to correspond to cases where the () expression is implicit in the source, and hence we do not take an expression argument.

The augment_error gives you a chance to extend the error message, in case any results (e.g., we use this to suggest removing a ;).

pub(crate) fn coerce_inner<'a>( &mut self, fcx: &FnCtxt<'a, 'tcx>, cause: &ObligationCause<'tcx>, expression: Option<&'tcx Expr<'tcx>>, expression_ty: Ty<'tcx>, augment_error: impl FnOnce(&mut Diagnostic), label_expression_as_expected: bool )

The inner coercion “engine”. If expression is None, this is a forced-unit case, and hence expression_ty must be Nil.

fn note_unreachable_loop_return( &self, err: &mut Diagnostic, expr: &Expr<'tcx>, ret_exprs: &Vec<&'tcx Expr<'tcx>> )

fn report_return_mismatched_types<'a>( &self, cause: &ObligationCause<'tcx>, expected: Ty<'tcx>, found: Ty<'tcx>, ty_err: TypeError<'tcx>, fcx: &FnCtxt<'a, 'tcx>, id: HirId, expression: Option<&'tcx Expr<'tcx>>, blk_id: Option<HirId> ) -> DiagnosticBuilder<'a, ErrorGuaranteed>

fn is_return_ty_definitely_unsized(&self, fcx: &FnCtxt<'_, 'tcx>) -> bool

Checks whether the return type is unsized via an obligation, which makes sure we consider dyn Trait: Sized where clauses, which are trivially false but technically valid for typeck.

pub fn complete<'a>(self, fcx: &FnCtxt<'a, 'tcx>) -> Ty<'tcx>

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: 48 bytes