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Rollup merge of #85920 - luqmana:wasm-linker-tweaks, r=petrochenkov

Tweak wasm_base target spec to indicate linker is not GNU and update linker inferring logic for wasm-ld.

Reported via [Zulip](https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/wasi.20linker.20unknown.20argument.3A.20--as-needed): we try passing `--as-needed` to the linker if it's GNU ld which `wasm-ld` is not. Usually this isn't an issue for wasm as we would use the WasmLd linker driver but because the linker in question (`wasm32-unknown-wasi-wasm-ld`) ended with `-ld` our linker inferring [logic](f64503eb55/compiler/rustc_codegen_ssa/src/back/link.rs (L957-L1040)) used the `GccLinker` implementations. (UPD: The linker inferring logic actually didn't apply in this case because the linker is actually invoked through gcc in the reported issue. But it's still worth updating the logic I think.)

This change then has 2 parts:
1. Update wasm_base target spec to indicate `linker_is_gnu: false` plus a few additions of `target.is_like_wasm` to handle flags `wasm-ld` does in fact support.
2. Improve the linker detection logic to properly determine the correct flavor of wasm linker we're using when we can.

We need to add the new `target.is_like_wasm` branches to handle the case where the "linker" used could be something like clang which would then under the hood call wasm-ld.
This commit is contained in:
Yuki Okushi 2021-06-06 19:11:18 +09:00 committed by GitHub
commit 679a1d1ac1
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3 changed files with 8 additions and 3 deletions

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@ -102,6 +102,7 @@ pub fn options() -> TargetOptions {
// we use the LLD shipped with the Rust toolchain by default
linker: Some("rust-lld".to_owned()),
lld_flavor: LldFlavor::Wasm,
linker_is_gnu: false,
pre_link_args,