🔬 This is a nightly-only experimental API. (rustc_private
)
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An "escaping region" is a bound region whose binder is not part of t
.
So, for example, consider a type like the following, which has two binders:
for<'a> fn(x: for<'b> fn(&'a isize, &'b isize))
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ outer scope
^~~~~~~~~~~~~~~~~~~~~~~~~~~~ inner scope
This type has bound regions ('a
, 'b
), but it does not have escaping regions, because the
binders of both 'a
and 'b
are part of the type itself. However, if we consider the inner
fn type, that type has an escaping region: 'a
.
Note that what I'm calling an "escaping region" is often just called a "free region". However,
we already use the term "free region". It refers to the regions that we use to represent bound
regions on a fn definition while we are typechecking its body.
To clarify, conceptually there is no particular difference between an "escaping" region and a
"free" region. However, there is a big difference in practice. Basically, when "entering" a
binding level, one is generally required to do some sort of processing to a bound region, such
as replacing it with a fresh/skolemized region, or making an entry in the environment to
represent the scope to which it is attached, etc. An escaping region represents a bound region
for which this processing has not yet been done.
🔬 This is a nightly-only experimental API. (rustc_private
)
this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via Cargo.toml
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Anything bound by outer_index
or "above" is escaping
🔬 This is a nightly-only experimental API. (rustc_private
)
this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via Cargo.toml
instead?
🔬 This is a nightly-only experimental API. (rustc_private
)
this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via Cargo.toml
instead?
🔬 This is a nightly-only experimental API. (rustc_private
)
this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via Cargo.toml
instead?
🔬 This is a nightly-only experimental API. (rustc_private
)
this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via Cargo.toml
instead?
🔬 This is a nightly-only experimental API. (rustc_private
)
this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via Cargo.toml
instead?
🔬 This is a nightly-only experimental API. (rustc_private
)
this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via Cargo.toml
instead?
🔬 This is a nightly-only experimental API. (try_from
)
The type returned in the event of a conversion error.
🔬 This is a nightly-only experimental API. (try_from
)
Immutably borrows from an owned value. Read more
type Error = <U as TryFrom<T>>::Error
🔬 This is a nightly-only experimental API. (try_from
)
The type returned in the event of a conversion error.
🔬 This is a nightly-only experimental API. (try_from
)
Mutably borrows from an owned value. Read more
🔬 This is a nightly-only experimental API. (get_type_id
)
this method will likely be replaced by an associated static
🔬 This is a nightly-only experimental API. (rustc_private
)
this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via Cargo.toml
instead?
Create an error for a missing method specialization. Defaults to panicking with type, trait & method names. S
is the encoder/decoder state type, T
is the type being encoded/decoded, and the arguments are the names of the trait and method that should've been overridden. Read more