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Jacob Pratt
494c6da389
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