Clarify sign/size of ABI types #279
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@tiziano88 Any thoughts? |
docs/abi.md
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| In this document, integer types are written as `u32` or `u64` to indicate that | ||
| the corresponding values will be treated as unsigned values. (There are | ||
| currently no uses of signed values in the ABI). |
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Maybe this should say that we use a more precise description for the types in the API, referring to the interpretation of those values as either signed or unsigned in the target language. I guess this relies on C++, Rust and other languages to perform conversions between those types in a compatible way (which hopefully is the case, but I have not checked). In fact, if you know of any such reference, it would be good to include a link here, so we know what we can safely rely on for each language.
I think my preferred approach would be to keep using i32 / i64 in the API function signatures, and explain how to interpret those values in the description of each method. But I'll leave that to you to decide anyways.
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I still prefer the u32 / u64 approach, not least to save boilerplate – every single parameter description in the ABI definition would need to have the same "This value is treated as an unsigned integer" / "This value is treated as an unsigned integer of size equivalent to Wasm linear memory size (currently always 32 bits)" text.
docs/abi.md
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| are written as the `usize` type, which is an alias for the `u32` type in the | ||
| current WebAssembly implementation(s). However, in any future | ||
| [64-bit ](https://github.com/WebAssembly/design/blob/master/FutureFeatures.md#linear-memory-bigger-than-4-gib) |
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| [64-bit ](https://github.com/WebAssembly/design/blob/master/FutureFeatures.md#linear-memory-bigger-than-4-gib) | |
| [64-bit](https://github.com/WebAssembly/design/blob/master/FutureFeatures.md#linear-memory-bigger-than-4-gib) |
Use u32/u64/usize everywhere (all ABI values are treated as unsigned), with usize specifically indicating a linear memory address or size (so any future Wasm64 port would map usize->u64 instead of u32).
Use u32/u64/usize everywhere (all ABI values are treated as unsigned),
with usize specifically indicating a linear memory address or size
(so any future Wasm64 port would map usize->u64 instead of u32).