23 lines
1.1 KiB
Markdown
23 lines
1.1 KiB
Markdown
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See https://github.com/rust-lang/rust/issues/107975
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Basically, if you have two pointers with the same address but from two different allocations,
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the compiler gets confused whether their addresses are equal or not,
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resulting in some self-contradictory behavior of the compiled code.
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This folder contains some examples.
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They all boil down to allocating a variable on the stack, taking its address,
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getting rid of the variable, and then doing it all again.
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This way we end up with two addresses stored in two `usize`s (`a` and `b`).
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The addresses are (probably) equal but (definitely) come from two different allocations.
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Logically, we would expect that exactly one of the following options holds true:
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1. `a == b`
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2. `a != b`
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Sadly, the compiler does not always agree.
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Due to Rust having at least three meaningfully different ways
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to get a variable's address as an `usize`,
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each example is provided in three versions, each in the corresponding subfolder:
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1. `./as-cast/` for `&v as *const _ as usize`,
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2. `./strict-provenance/` for `addr_of!(v).addr()`,
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2. `./exposed-provenance/` for `addr_of!(v).expose_provenance()`.
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