Module inhabitedness 

This module contains logic for determining whether a type is inhabited or uninhabited. The InhabitedPredicate type captures the minimum information needed to determine whether a type is inhabited given a ParamEnv and module ID.

Example

mod a {
    pub mod b {
        pub struct SecretlyUninhabited {
            _priv: !,
        }
    }
}

mod c {
    enum Void {}
    pub struct AlsoSecretlyUninhabited {
        _priv: Void,
    }
    mod d {
    }
}

struct Foo {
    x: a::b::SecretlyUninhabited,
    y: c::AlsoSecretlyUninhabited,
}

In this code, the type Foo will only be visibly uninhabited inside the modules b, c and d. Calling inhabited_predicate on Foo will return NotInModule(b) AND NotInModule(c).

We need this information for pattern-matching on Foo or types that contain Foo.

Example

let foo_result: Result<T, Foo> = ... ;
let Ok(t) = foo_result;

This code should only compile in modules where the uninhabitedness of Foo is visible.

Re-exports

use rustc_data_structures::fx::FxHashSet; 🔒

use rustc_hir::def::DefKind; 🔒

use rustc_span::bug; 🔒

use rustc_span::def_id::LocalModId; 🔒

use tracing::instrument; 🔒

use tracing::instrument; 🔒

use crate::query::Providers; 🔒

use crate::ty; 🔒

use crate::ty::AdtDef; 🔒

use crate::ty::DefId; 🔒

use crate::ty::Ty; 🔒

use crate::ty::TyCtxt; 🔒

use crate::ty::TypeVisitableExt; 🔒

use crate::ty::TypingEnv; 🔒

use crate::ty::VariantDef; 🔒

use crate::ty::Visibility; 🔒

pub use inhabited_predicate::InhabitedPredicate;

use rustc_type_ir::TyKind::*; 🔒

Modules

inhabited_predicate

Structs

OpsemInhabitedCtx 🔒

Context for computing whether a type is inhabited on the opsem level. See is_opsem_inhabited above for the spec of what we compute.

Functions

inhabited_predicate_for_def 🔒

Returns an InhabitedPredicate that is generic over type parameters and requires calling InhabitedPredicate::instantiate

inhabited_predicate_type 🔒

N.B. this query should only be called through Ty::inhabited_predicate

is_opsem_inhabited_adt_cached 🔒

provide 🔒

variant_inhabited_predicate 🔒