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1//! A "bare wasm" target representing a WebAssembly output that makes zero
2//! assumptions about its environment.
3//!
4//! The `wasm32-unknown-unknown` target is intended to encapsulate use cases
5//! that do not rely on any imported functionality. The binaries generated are
6//! entirely self-contained by default when using the standard library. Although
7//! the standard library is available, most of it returns an error immediately
8//! (e.g. trying to create a TCP stream or something like that).
9//!
10//! This target is more or less managed by the Rust and WebAssembly Working
29967ef6 11//! Group nowadays at <https://github.com/rustwasm>.
532ac7d7 12
cdc7bbd5 13use super::wasm_base;
dfeec247 14use super::{LinkerFlavor, LldFlavor, Target};
cdc7bbd5 15use crate::spec::abi::Abi;
abe05a73 16
29967ef6 17pub fn target() -> Target {
cdc7bbd5 18 let mut options = wasm_base::options();
5e7ed085 19 options.os = "unknown".into();
29967ef6 20 options.linker_flavor = LinkerFlavor::Lld(LldFlavor::Wasm);
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21
22 // This is a default for backwards-compatibility with the original
23 // definition of this target oh-so-long-ago. Once the "wasm" ABI is
24 // stable and the wasm-bindgen project has switched to using it then there's
25 // no need for this and it can be removed.
26 //
27 // Currently this is the reason that this target's ABI is mismatched with
28 // clang's ABI. This means that, in the limit, you can't merge C and Rust
29 // code on this target due to this ABI mismatch.
30 options.default_adjusted_cabi = Some(Abi::Wasm);
31
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32 options.add_pre_link_args(
33 LinkerFlavor::Lld(LldFlavor::Wasm),
34 &[
35 // For now this target just never has an entry symbol no matter the output
36 // type, so unconditionally pass this.
37 "--no-entry",
38 // Rust really needs a way for users to specify exports and imports in
39 // the source code. --export-dynamic isn't the right tool for this job,
40 // however it does have the side effect of automatically exporting a lot
41 // of symbols, which approximates what people want when compiling for
42 // wasm32-unknown-unknown expect, so use it for now.
43 "--export-dynamic",
44 ],
45 );
46 options.add_pre_link_args(
47 LinkerFlavor::Gcc,
48 &[
49 // Make sure clang uses LLD as its linker and is configured appropriately
50 // otherwise
51 "--target=wasm32-unknown-unknown",
52 "-Wl,--no-entry",
53 "-Wl,--export-dynamic",
54 ],
55 );
0bf4aa26 56
29967ef6 57 Target {
5e7ed085 58 llvm_target: "wasm32-unknown-unknown".into(),
29967ef6 59 pointer_width: 32,
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60 data_layout: "e-m:e-p:32:32-p10:8:8-p20:8:8-i64:64-n32:64-S128-ni:1:10:20".into(),
61 arch: "wasm32".into(),
532ac7d7 62 options,
29967ef6 63 }
abe05a73 64}