Show the crate…
4 stable releases
3.0.1 | May 20, 2021 |
---|---|
3.0.0 | Mar 8, 2021 |
2.1.2 | Jun 23, 2021 |
1.0.9 | Apr 6, 2021 |
0.0.0 |
|
#17 in #tetcoin
Used in 13 crates
(3 directly)
49KB
789 lines
Wasm builder is a utility for building a project as a Wasm binary
The Wasm builder is a tool that integrates the process of building the WASM binary of your project into the main
cargo
build process.
Project setup
A project that should be compiled as a Wasm binary needs to:
- Add a
build.rs
file. - Add
wasm-builder
as dependency intobuild-dependencies
.
The build.rs
file needs to contain the following code:
use wasm_builder::WasmBuilder;
fn main() {
WasmBuilder::new()
// Tell the builder to build the project (crate) this `build.rs` is part of.
.with_current_project()
// Make sure to export the `heap_base` global, this is required by Tetcore
.export_heap_base()
// Build the Wasm file so that it imports the memory (need to be provided by at instantiation)
.import_memory()
// Build it.
.build()
}
As the final step, you need to add the following to your project:
include!(concat!(env!("OUT_DIR"), "/wasm_binary.rs"));
This will include the generated Wasm binary as two constants WASM_BINARY
and WASM_BINARY_BLOATY
.
The former is a compact Wasm binary and the latter is the Wasm binary as being generated by the compiler.
Both variables have Option<&'static [u8]>
as type.
Features
Wasm builder supports to enable cargo features while building the Wasm binary. By default it will
enable all features in the wasm build that are enabled for the native build except the
default
and std
features. Besides that, wasm builder supports the special runtime-wasm
feature. This runtime-wasm
feature will be enabled by the wasm builder when it compiles the
Wasm binary. If this feature is not present, it will not be enabled.
Environment variables
By using environment variables, you can configure which Wasm binaries are built and how:
SKIP_WASM_BUILD
- Skips building any Wasm binary. This is useful when only native should be recompiled. If this is the first run and there doesn't exist a Wasm binary, this will set both variables toNone
.WASM_BUILD_TYPE
- Sets the build type for building Wasm binaries. Supported values arerelease
ordebug
. By default the build type is equal to the build type used by the main build.FORCE_WASM_BUILD
- Can be set to force a Wasm build. On subsequent calls the value of the variable needs to change. As wasm-builder instructscargo
to watch for file changes this environment variable should only be required in certain circumstances.WASM_BUILD_RUSTFLAGS
- ExtendRUSTFLAGS
given tocargo build
while building the wasm binary.WASM_BUILD_NO_COLOR
- Disable color output of the wasm build.WASM_TARGET_DIRECTORY
- Will copy any build Wasm binary to the given directory. The path needs to be absolute.WASM_BUILD_TOOLCHAIN
- The toolchain that should be used to build the Wasm binaries. The format needs to be the same as used by cargo, e.g.nightly-2020-02-20
.
Each project can be skipped individually by using the environment variable SKIP_PROJECT_NAME_WASM_BUILD
.
Where PROJECT_NAME
needs to be replaced by the name of the cargo project, e.g. node-runtime
will
be NODE_RUNTIME
.
Prerequisites:
Wasm builder requires the following prerequisites for building the Wasm binary:
- rust nightly +
wasm32-unknown-unknown
toolchain
If a specific rust nightly is installed with rustup
, it is important that the wasm target is installed
as well. For example if installing the rust nightly from 20.02.2020 using rustup install nightly-2020-02-20
,
the wasm target needs to be installed as well rustup target add wasm32-unknown-unknown --toolchain nightly-2020-02-20
.
License: Apache-2.0
Dependencies
~5–14MB
~202K SLoC