rust/library/core
Jacob Pratt 494c6da389
Rollup merge of #150601 - folkertdev:c-variadic-const-eval, r=RalfJung
support c-variadic functions in `rustc_const_eval`

tracking issue: https://github.com/rust-lang/rust/issues/44930

The new `GlobalAlloc::VaList` is used to create an `AllocId` that represents the variable argument list of a frame. The allocation itself does not store any data, all we need is the unique identifier.

The actual variable argument list is stored in `Memory`, and keyed by the `AllocId`. The `Frame` also stores this `AllocId`, so that when a frame is popped, it can deallocate the variable arguments.

At "runtime" a `VaList` value stores a pointer to the global allocation in its first bytes. The provenance on this pointer can be used to retrieve its `AllocId`, and the offset of the pointer is used to store the index of the next argument to read from the variable argument list.

Miri does not yet support `va_arg`, but I think that can be done separetely?

r? @RalfJung
cc @workingjubilee
2026-02-16 04:28:56 -05:00
..
src Rollup merge of #150601 - folkertdev:c-variadic-const-eval, r=RalfJung 2026-02-16 04:28:56 -05:00
Cargo.toml add autodiff examples 2025-11-16 23:35:37 -05:00