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//! A "bare wasm" target representing a WebAssembly output that makes zero
//! assumptions about its environment.
//!
//! The `wasm32-unknown-unknown` target is intended to encapsulate use cases
//! that do not rely on any imported functionality. The binaries generated are
//! entirely self-contained by default when using the standard library. Although
//! the standard library is available, most of it returns an error immediately
//! (e.g. trying to create a TCP stream or something like that).
//!
//! This target is more or less managed by the Rust and WebAssembly Working
//! Group nowadays at <https://github.com/rustwasm>.
use super::wasm_base;
use super::{LinkerFlavor, LldFlavor, Target};
use crate::spec::abi::Abi;
pub fn target() -> Target {
let mut options = wasm_base::options();
options.os = "unknown".into();
options.linker_flavor = LinkerFlavor::Lld(LldFlavor::Wasm);
// This is a default for backwards-compatibility with the original
// definition of this target oh-so-long-ago. Once the "wasm" ABI is
// stable and the wasm-bindgen project has switched to using it then there's
// no need for this and it can be removed.
//
// Currently this is the reason that this target's ABI is mismatched with
// clang's ABI. This means that, in the limit, you can't merge C and Rust
// code on this target due to this ABI mismatch.
options.default_adjusted_cabi = Some(Abi::Wasm);
options.add_pre_link_args(
LinkerFlavor::Lld(LldFlavor::Wasm),
&[
// For now this target just never has an entry symbol no matter the output
// type, so unconditionally pass this.
"--no-entry",
// Rust really needs a way for users to specify exports and imports in
// the source code. --export-dynamic isn't the right tool for this job,
// however it does have the side effect of automatically exporting a lot
// of symbols, which approximates what people want when compiling for
// wasm32-unknown-unknown expect, so use it for now.
"--export-dynamic",
],
);
options.add_pre_link_args(
LinkerFlavor::Gcc,
&[
// Make sure clang uses LLD as its linker and is configured appropriately
// otherwise
"--target=wasm32-unknown-unknown",
"-Wl,--no-entry",
"-Wl,--export-dynamic",
],
);
Target {
llvm_target: "wasm32-unknown-unknown".into(),
pointer_width: 32,
data_layout: "e-m:e-p:32:32-p10:8:8-p20:8:8-i64:64-n32:64-S128-ni:1:10:20".into(),
arch: "wasm32".into(),
options,
}
}
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