Add wasm-opt-for-rust proposal

applications/wasm-opt-for-rust.md

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+# W3F Grant Proposal
+
+- **Project Name:** `wasm-opt` for Rust
+- **Team Name:** Common Orbit LLC
+- **Payment Address:** (Polkadot aUSD) 143W7CfR2R1dbATX3RVtrYfDXUMju1ua9pQh9B3DpLsuuB5M
+- **[Level](https://github.com/w3f/Grants-Program/tree/master#level_slider-levels):** 2
+
+
+
+
+## Project Overview :page_facing_up:
+
+### Overview
+
+This project makes the [`wasm-opt`] tool more accessible to Rust programmers.
+`wasm-opt` is a [WebAssembly] optimizer and is required by most software toolchains that
+produce WebAssembly binaries.
+
+[`wasm-opt`]: https://rustwasm.github.io/book/reference/tools.html#wasm-opt--a-hrefhttpsgithubcomwebassemblybinaryenrepositorya
+[WebAssembly]: https://webassembly.org/
+
+This project is to package `wasm-opt` as a cargo crate,
+so that it can be installed by typing
+
+> `cargo install wasm-opt`
+
+Additionally, it will provide a Rust API so that toolchain developers may,
+if they desire, call `wasm-opt` programmatically,
+so that their users are not required to manually install the tool.
+
+`wasm-opt` is a part of the [binaryen] toolset, written in C++.
+It is almost universally required by all toolchains that compile to WebAssembly.
+It is required by Parity's [`cargo-contract`] tool for [ink!] development.
+
+[binaryen]: https://github.com/WebAssembly/binaryen
+[`cargo-contract`]: https://github.com/paritytech/cargo-contract
+[ink!]: https://github.com/paritytech/ink
+
+**This tool can not be aquired in the way Rust programmers expect — with `cargo install`.**
+Installation of the tool is system-dependent.
+Many system package managers have some version of it,
+in some cases an old version;
+or it can be downloaded in binary form for most platforms, from GitHub,
+in which case it has to be extracted and added to the environment `PATH` variable in an ad-hoc way.
+
+In [our personal experience][wasmexp], aquiring this tool was a minor, but needless, barrier, to programming with [ink!].
+
+[wasmexp]: #appendix-the-wasm-opt-installation-experience
+
+In the course of this grant `cargo-contract` will receive pull requests
+to optionally enable both the following:
+
+1) recommend installation via `cargo install wasm-opt`
+2) use `wasm-opt` via API and not require installation.
+
+
+
+
+### Project Details
+
+Note that although `wasm-opt` comes from the binaryen suite of tools,
+this project is only focused on `wasm-opt`.
+All other binaryen tools are out of scope.
+If this project is successful and there is demand,
+future work can extend the technique to the rest of binaryen.
+
+This project is technically straightforward.
+The main complication is that within `cargo` it is not possible to install binaries that were not produced
+directly by the Rust compiler.
+This means that it is not possible to simply build `wasm-opt` in a build script, then have `cargo` install it.
+
+This is the basic approach we will take, for the executable:
+
+- a `wasm-opt-sys` crate builds the C++ code for `wasm-opt`
+- the C++ source is built with only the C++ compiler all Rust users will have installed,
+  no CMake or other build-system dependency
+- the C++ `wasm-opt` source is minimally-patched to export its `main` function with C ABI to be called from Rust
+- a `wasm-opt` crate contains a tiny Rust module that calls the C `wasm-opt` main function
+
+We have prototyped the project sufficiently to believe the described approach will succeed.
+
+For the library bindings:
+
+- `wasm-opt-sys` will export low-level Rust bindings with the help of one
+  of the common C++-integration crates, likely `cxx`
+- `wasm-opt` will provide an idiomatic Rust wrapper that exposes the necessary `wasm-opt` options programmatically
+
+We will also deliver the following:
+
+- Full README and API documentation
+- Basic regression tests for the binary and library
+- CI for the platforms
+  - `aarch64-apple-darwin`
+  - `aarch64-unknown-linux-gnu`
+  - `i686-pc-windows-msvc`
+  - `i686-unknown-linux-gnu`
+  - `x86_64-apple-darwin`
+  - `x86_64-pc-windows-msvc`
+  - `x86_64-unknown-linux-gnu`
+- Pull requests adding optional support for the `wasm-opt` crate to
+  - `cargo-contract`, the ink! build tool
+- One blog post about the tool and its development, at https://brson.github.io
+
+
+
+
+### Ecosystem Fit
+
+This project is immediately useful to all Rust developers that build for wasm.
+
+It is more specifically useful to developers of Rust-based toolchains that target wasm,
+and most specifically the `cargo-contract` tool used to compile ink! programs.
+It is probably relevant to authors of Substrate runtimes as well,
+though we do not have that experience yet.
+
+
+#### Prior Work and Alternatives
+
+There are existing [Rust bindings for binaryen][brs].
+As-is they don't provide a route to installing `wasm-opt` via cargo.
+It is unclear if they provide the APIs needed to expose `wasm-opt` programmatically,
+though they probably do.
+These bindings appear to rely on CMake to build.
+We do not expect to use them directly, but may reference them during development.
+
+[brs]: https://github.com/pepyakin/binaryen-rs
+
+The [`cargo-wasi`] tool takes a [different strategy][cws] to acquiring `wasm-opt`.
+It automatically downloads the `wasm-opt` binary, presumably from the official releases.
+Other wasm toolchains like `cargo-contract` could follow a similar strategy,
+possibly by extracting the existing logic from `cargo-wasi`.
+
+[`cargo-wasi`]: https://github.com/bytecodealliance/cargo-wasi
+[cws]: https://bytecodealliance.github.io/cargo-wasi/wasm-opt.html#which-wasm-opt-executed
+
+
+
+
+
+## Team :busts_in_silhouette:
+
+### Team members
+
+- **Team lead:** [Brian Anderson](https://github.com/brson)
+- **Team member:** [Aimee Zhu](https://github.com/aimeedeer)
+
+### Contact
+
+- **Contact Name:** Brian Anderson
+- **Contact Email:** [email protected]
+- **Website:** https://brson.github.io
+
+### Legal Structure
+
+- **Registered Address:** 16192 Coastal Highway, Lewes, Delaware 19958
+- **Registered Legal Entity:** Common Orbit LLC
+
+### Team's experience
+
+The team lead is one of the original authors of the Rust programming language,
+with 12 years of Rust experience.
+They have performed Rust work for Mozilla, Reddit, PingCAP, Solana, MobileCoin, Parity, and Nervos.
+Both team members are maintainers of the [Rust in Blockchain](https://rustinblockchain.org/) newsletter.
+
+### Team Code Repos
+
+- https://github.com/brson/wasm-opt-rs
+- https://github.com/brson
+- https://github.com/aimeedeer
+
+### Team LinkedIn Profiles (if available)
+
+N/A
+
+
+
+
+## Development Status :open_book:
+
+https://github.com/brson/wasm-opt-rs
+
+We have created the initial project layout and investigated the feasibility of building the binaryen codebase using only the [`cc`] crate,
+as well as the feasibility of trivially calling the `wasm-opt` `main` function from Rust as described.
+
+[`cc`]: https://docs.rs/cc/latest/cc/
+
+We have reserved the `wasm-opt` and `wasm-opt-sys` crate names on crates.io.
+
+
+
+
+## Development Roadmap :nut_and_bolt:
+
+### Overview
+
+- **Total Estimated Duration:** 3-4 months
+- **Full-Time Equivalent (FTE):**  0.4
+- **Total Costs:** 30,000 USD
+
+This will be a part time effort.
+I have divided this into two logical milestones,
+though in reality the work will overlap.
+
+
+### Milestone 1 — Proof of Concept
+
+- **Estimated duration:** 1-2 month
+- **FTE:**  0.4
+- **Costs:** 15,000 USD
+
+During this phase we will prove the concept and produce a `wasm-opt` Rust binary and API.
+
+| Number | Deliverable | Specification |
+| -----: | ----------- | ------------- |
+| 0a. | License | MIT / Apache-2.0 |
+| 0b. | Documentation | Basic README. |
+| 0c. | Testing Guide | Manual smoke testing on Linux, Windows, and MacOS, x86_64 and ARM. |
+| 0d. | Docker | Docker is not required for this project. |
+| 1. | `wasm-opt` binary | Produce a `wasm-opt` binary that can be built by cargo but is otherwise identical to stock `wasm-opt`. |
+| 2. | APIs | Write an idiomatic, but possibly incomplete, Rust API for loading wasm, optimizing it, and writing it again. |
+
+
+### Milestone 2 — Integration
+
+- **Estimated duration:** 1-2 month
+- **FTE:**  0.4
+- **Costs:** 15,000 USD
+
+During this phase we will prepare the project for production and integrate it with `cargo-contract`.
+
+| Number | Deliverable | Specification |
+| -----: | ----------- | ------------- |
+| 0a. | License | MIT / Apache-2.0 |
+| 0b. | Documentation | Full README and API docs. |
+| 0c. | Testing Guide | Basic integration tests for both binary and library. |
+| 0d. | Docker | Docker is not required for this project. |
+| 0e. | Article | Publish a technical blog post about how the project was developed and indicating it is available for use. |
+| 1. | APIs | Ensure the APIs expose all the `wasm-opt` options, and can be easily integrated into tools like `cargo-contract`. |
+| 2. | `cargo-contract` integration | Submit a PR to `cargo-contract` that integrates the `wasm-opt` crate. |
+| 3. | CI | Set up CI for all indicated platforms. |
+
+
+
+
+## Future Plans
+
+Upon completion of this project we will pursue a maintainence grant
+to supply hourly funds for maintenance of this project.
+We expect maintenance to be minimal,
+primarily updating the code and making new releases to match upstream binaryen releases,
+and responding to issue reports.
+
+We are interested in pursuing a pure-Rust alternative to `wasm-opt` with a limited
+focus of quickly shrinking wasm binaries.
+
+We expect to pursue additional projects related to ink! and Substrate.
+
+
+
+
+## Appendix: The `wasm-opt` installation experience
+
+Upon calling `cargo-contract build` without `wasm-opt` installed
+the build errors with this long explanation:
+
+```
+ERROR: wasm-opt not found! Make sure the binary is in your PATH environment.
+
+We use this tool to optimize the size of your contract's Wasm binary.
+
+wasm-opt is part of the binaryen package. You can find detailed
+installation instructions on https://github.com/WebAssembly/binaryen#tools.
+
+There are ready-to-install packages for many platforms:
+* Debian/Ubuntu: apt-get install binaryen
+* Homebrew: brew install binaryen
+* Arch Linux: pacman -S binaryen
+* Windows: binary releases at https://github.com/WebAssembly/binaryen/releases
+```
+
+Despite the effort to explain how to install this tool,
+following the instructions on our system resulted in an old version of `wasm-opt`
+and `cargo-contract` produced a new error:
+
+```
+ERROR: Your wasm-opt version is 91, but we require a version >= 99.
+
+If you tried installing from your system package manager the best
+way forward is to download a recent binary release directly:
+
+https://github.com/WebAssembly/binaryen/releases
+
+Make sure that the `wasm-opt` file from that release is in your `PATH`.
+```
+
+This actually did about the best that could be expected to help us
+get set up, and we did end up downloading the binary tarball,
+extracting it, and modifying our path.
+But the experience could be better.