Rename wasm32-wasi to wasm32-wasip1

[sunfishcode]

I propose to rename clang's wasm32-wasi target to wasm32-wasip1. This will align clang with Rust and Go, and it eventually free up the name "wasm32-wasi" for a future WASI 1.0 standard.

The name "wasm32-wasi" would continue to be recognized as an alias for "wasm32-wasip1" for several clang releases, though it would evoke a deprecation warning, like this:

$ clang -c t.c --target=wasm32-wasi
clang: warning: argument '--target=wasm32-wasi' is deprecated, use --target=wasm32-wasip1 instead [-Wdeprecated]
$

As just a warning, it wouldn't break builds (unless users ask it to, with -Werror).

wasm32-wasip1 is already accepted by all versions of clang that support wasm32-wasi, because clang's target code just checks that the OS name starts with "wasi" and ignores anything after that. Consequently, users can migrate their build scripts to "wasm32-wasip1" at any time, without having to upgrade to a new version, or drop support for old versions. You can literally use "wasm32-wasip1" today if you wish, and it'll work with past and future versions.

Users using the default target in wasi-sdk would not need to make any changes.

[llvmbot]

@llvm/issue-subscribers-backend-webassembly

Author: Dan Gohman (sunfishcode)

I propose to rename clang's wasm32-wasi target to wasm32-wasip1. This will align clang with [Rust] and [Go], and it eventually free up the name "wasm32-wasi" for a future WASI 1.0 standard.

The name "wasm32-wasi" would continue to be recognized as an alias for "wasm32-wasip1" for several clang releases, though it would evoke a deprecation warning, like this:

$ clang -c t.c --target=wasm32-wasi
clang: warning: argument '--target=wasm32-wasi' is deprecated, use --target=wasm32-wasip1 instead [-Wdeprecated]
$

As just a warning, it wouldn't break builds (unless users ask it to, with -Werror).

wasm32-wasip1 is already accepted by all versions of clang that support wasm32-wasi, because clang's target code just checks that the OS name starts with "wasi" and ignores anything after that. Consequently, users can migrate their build scripts to "wasm32-wasip1" at any time, without having to upgrade to a new version, or drop support for old versions. You can literally use "wasm32-wasip1" today if you wish, and it'll work with past and future versions.

Users using the default target in wasi-sdk would not need to make any changes.

[alexrp]

I'm not necessarily saying LLVM/Clang should do this, and it ultimately doesn't matter too much for us on the Zig side, but some food for thought: The way we've modeled this is that there's just a single wasi OS tag and we use the standard OS version range syntax in the triple to represent the WASI version, with 0.1.0 being preview 1, etc. LLVM already supports a singular OS version in the triple, so that could be used for this purpose just as we do on the Zig side.

[sunfishcode]

I don't have a strong preference between "wasip1" or "wasi0.1.0"; I picked "wasip1" because it's what Rust and Go already call their targets.