docs: Document and advertise our support for various Wasm proposals

docs/SUMMARY.md

@@ -45,6 +45,7 @@
 - [Stability](stability.md)
   - [Release Process](./stability-release.md)
   - [Platform Support](./stability-platform-support.md)
+  - [Wasm Proposals Support](./stability-wasm-proposals-support.md)
 - [Security](security.md)
   - [Disclosure Policy](./security-disclosure.md)
   - [Sandboxing](./security-sandboxing.md)

docs/stability-wasm-proposals-support.md

@@ -0,0 +1,34 @@
+# WebAssembly Proposals Support
+
+The following table summarizes Wasmtime's support for WebAssembly proposals as
+well as the command line flag and [`wasmtime::Config`][config] method you can
+use to enable or disable support for a proposal.
+
+If a proposal is not listed, then it is not supported by Wasmtime.
+
+Wasmtime will never enable a proposal by default unless it has reached phase 4
+of [the WebAssembly standardizations process][phases] and its implementation in
+Wasmtime has been [thoroughly
+vetted](./contributing-supporting-new-wasm-proposals.html).
+
+| WebAssembly Proposal                        | Supported in Wasmtime?           | Command Line Flag      | [`Config`][config] Method |
+|---------------------------------------------|----------------------------------|------------------------|---------------------------|
+| **[Import and Export Mutable Globals]**     | **Yes.**<br/>Always enabled.     | (none)                 | (none)                    |
+| **[Sign-Extension Operations]**             | **Yes.**<br/>Always enabled.     | (none)                 | (none)                    |
+| **[Non-Trapping Float-to-Int Conversions]** | **Yes.**<br/>Always enabled.     | (none)                 | (none)                    |
+| **[Multi-Value]**                           | **Yes.**<br/>Enabled by default. | `--enable-multi-value` | [`wasm_multi_value`](https://docs.rs/wasmtime/*/wasmtime/struct.Config.html#method.wasm_multi_value) |
+| **[Bulk Memory Operations]**                | **Yes.**<br/>Enabled by default. | `--enable-bulk-memory` | [`wasm_bulk_memory`](https://docs.rs/wasmtime/*/wasmtime/struct.Config.html#method.wasm_bulk_memory) |
+| **[Reference Types]**                       | **Yes.**<br/>Enabled by default on x86_64. Aarch64 support in progress. | `--enable-reference-types` | [`wasm_reference_types`](https://docs.rs/wasmtime/*/wasmtime/struct.Config.html#method.wasm_reference_types) |
+| **[Fixed-Width SIMD]**                      | **In progress.**                 | `--enable-simd`        | [`wasm_simd`](https://docs.rs/wasmtime/*/wasmtime/struct.Config.html#method.wasm_simd) |
+| **[Threads and Atomics]**                   | **In progress.**                 | `--enable-threads`     | [`wasm_threads`](https://docs.rs/wasmtime/*/wasmtime/struct.Config.html#method.wasm_threads) |
+
+[config]: https://docs.rs/wasmtime/*/wasmtime/struct.Config.html
+[Multi-Value]: https://github.com/WebAssembly/spec/blob/master/proposals/multi-value/Overview.md
+[Bulk Memory Operations]: https://github.com/WebAssembly/bulk-memory-operations/blob/master/proposals/bulk-memory-operations/Overview.md
+[Import and Export Mutable Globals]: https://github.com/WebAssembly/mutable-global/blob/master/proposals/mutable-global/Overview.md
+[Reference Types]: https://github.com/WebAssembly/reference-types/blob/master/proposals/reference-types/Overview.md
+[Non-Trapping Float-to-Int Conversions]: https://github.com/WebAssembly/spec/blob/master/proposals/nontrapping-float-to-int-conversion/Overview.md
+[Sign-Extension Operations]: https://github.com/WebAssembly/spec/blob/master/proposals/sign-extension-ops/Overview.md
+[Fixed-Width SIMD]: https://github.com/WebAssembly/simd/blob/master/proposals/simd/SIMD.md
+[phases]: https://github.com/WebAssembly/meetings/blob/master/process/phases.md
+[Threads and Atomics]: https://github.com/WebAssembly/threads/blob/master/proposals/threads/Overview.md