struct DropCtxt<'l, 'b, 'tcx, D>where
    D: DropElaborator<'b, 'tcx>,
{ elaborator: &'l mut D, source_info: SourceInfo, place: Place<'tcx>, path: D::Path, succ: BasicBlock, unwind: Unwind, }

Fields

elaborator: &'l mut Dsource_info: SourceInfoplace: Place<'tcx>path: D::Pathsucc: BasicBlockunwind: Unwind

Implementations

This elaborates a single drop instruction, located at bb, and patches over it.

The elaborated drop checks the drop flags to only drop what is initialized.

In addition, the relevant drop flags also need to be cleared to avoid double-drops. However, in the middle of a complex drop, one must avoid clearing some of the flags before they are read, as that would cause a memory leak.

In particular, when dropping an ADT, multiple fields may be joined together under the rest subpath. They are all controlled by the primary drop flag, but only the last rest-field dropped should clear it (and it must also not clear anything else).

Returns the place and move path for each field of variant, (the move path is None if the field is a rest field).

Creates one-half of the drop ladder for a list of fields, and return the list of steps in it in reverse order, with the first step dropping 0 fields and so on.

unwind_ladder is such a list of steps in reverse order, which is called if the matching step of the drop glue panics.

Creates a full drop ladder, consisting of 2 connected half-drop-ladders

For example, with 3 fields, the drop ladder is

.d0: ELAB(drop location.0 [target=.d1, unwind=.c1]) .d1: ELAB(drop location.1 [target=.d2, unwind=.c2]) .d2: ELAB(drop location.2 [target=self.succ, unwind=self.unwind]) .c1: ELAB(drop location.1 [target=.c2]) .c2: ELAB(drop location.2 [target=self.unwind])

NOTE: this does not clear the master drop flag, so you need to point succ/unwind on a drop_ladder_bottom.

Create a loop that drops an array:

loop-block:
   can_go = cur == length_or_end
   if can_go then succ else drop-block
drop-block:
   if ptr_based {
       ptr = cur
       cur = cur.offset(1)
   } else {
       ptr = &raw mut P[cur]
       cur = cur + 1
   }
   drop(ptr)

Creates a pair of drop-loops of place, which drops its contents, even in the case of 1 panic. If ptr_based, creates a pointer loop, otherwise create an index loop.

The slow-path - create an “open”, elaborated drop for a type which is moved-out-of only partially, and patch bb to a jump to it. This must not be called on ADTs with a destructor, as these can’t be moved-out-of, except for Box<T>, which is special-cased.

This creates a “drop ladder” that drops the needed fields of the ADT, both in the success case or if one of the destructors fail.

Creates a block that resets the drop flag. If mode is deep, all children drop flags will also be cleared.

Creates a block that frees the backing memory of a Box if its drop is required (either statically or by checking its drop flag).

The contained value will not be dropped.

Creates a block that frees the backing memory of a Box (without dropping the contained value).

Returns the block to jump to in order to test the drop flag and execute the drop.

Depending on the required DropStyle, this might be a generated block with an if terminator (for dynamic/open drops), or it might be on_set or on_unset itself, in case the drop can be statically determined.

Trait Implementations

Formats the value using the given formatter. Read more

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

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

The type returned in the event of a conversion error.
Performs the conversion.
The type returned in the event of a conversion error.
Performs the conversion.

Layout

Note: Unable to compute type layout, possibly due to this type having generic parameters. Layout can only be computed for concrete, fully-instantiated types.