Fix linking for wasm with crate metadata included#158242
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Mark-Simulacrum
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| let mut symbols = if let CrateType::ProcMacro = crate_type { | ||
| exported_symbols_for_proc_macro_crate(tcx) |
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I guess the other part that both wasm-macro PRs implement is altering this -- I altered it to just let symbols get exported per normal rules under -Zwasm-proc-macros, and I think you hardcoded a set of symbols for export (https://github.com/rust-lang/rust/pull/157709/changes#diff-3f87e69f5e21712681d6fca5b6b70542c10eaf49bf48ff16445ddd17f1ae6dadR1876-R1880).
I think that can go in a separate PR though (up to you).
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Indeed. I intentionally didn't do it in this PR as we both need a different set of symbols exported.
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I guess my thinking is that we should let the proc macro (expanded) source control symbols, as with normal ~dylibs -- there's a separate pass enforcing that the public API is restricted to proc-macro functions already (that would then get altered a bit under both of our PRs).
But yeah, we can leave it for future work.
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there's a separate pass enforcing that the public API is restricted to proc-macro functions already
That doesn't apply to #[no_mangle] in dependencies. That is the reason why this extra code path exists: #99944
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Ah, I see. Yeah, that's trickier.
I'm not sure how much we should be worried about extra symbols getting exposed on wasm targets though, since we don't really have symbol conflicts there (right?). Code size is a concern still of course.
On wasm the crate metadata ends up in a custom section. It is not possible to refer to create symbols inside a custom section, so attempting to export it during linking will result in a linker error. This keeps the target spec flag to deny compiling rust dylibs for wasm, but may theoretically allow compiling wasm rust dylibs with a custom target spec. It will help with wasm proc-macros. And in the future we can try to flip the only-cdylib option to false on wasm.
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…=Mark-Simulacrum Fix linking for wasm with crate metadata included On wasm the crate metadata ends up in a custom section. It is not possible to refer to create symbols inside a custom section, so attempting to export it during linking will result in a linker error. This keeps the target spec flag to deny compiling rust dylibs for wasm, but may theoretically allow compiling wasm rust dylibs with a custom target spec. It will help with wasm proc-macros. And in the future we can try to flip the only-cdylib option to false on wasm. Extracted out of rust-lang#157709, but also helps with rust-lang#157590. r? @Mark-Simulacrum
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…=Mark-Simulacrum Fix linking for wasm with crate metadata included On wasm the crate metadata ends up in a custom section. It is not possible to refer to create symbols inside a custom section, so attempting to export it during linking will result in a linker error. This keeps the target spec flag to deny compiling rust dylibs for wasm, but may theoretically allow compiling wasm rust dylibs with a custom target spec. It will help with wasm proc-macros. And in the future we can try to flip the only-cdylib option to false on wasm. Extracted out of rust-lang#157709, but also helps with rust-lang#157590. r? @Mark-Simulacrum
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…uwer Rollup of 5 pull requests Successful merges: - #155811 (Include AtomicU128/AtomicI128 in docs for any target) - #158242 (Fix linking for wasm with crate metadata included) - #158119 (Refactor `proc_macro_decls_static`) - #158172 (update `asm_experimental_reg` comments) - #158230 (Include `Item::stability` info in rustdoc JSON.)
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…=Mark-Simulacrum Fix linking for wasm with crate metadata included On wasm the crate metadata ends up in a custom section. It is not possible to refer to create symbols inside a custom section, so attempting to export it during linking will result in a linker error. This keeps the target spec flag to deny compiling rust dylibs for wasm, but may theoretically allow compiling wasm rust dylibs with a custom target spec. It will help with wasm proc-macros. And in the future we can try to flip the only-cdylib option to false on wasm. Extracted out of rust-lang#157709, but also helps with rust-lang#157590. r? @Mark-Simulacrum
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…uwer Rollup of 7 pull requests Successful merges: - #157983 (Lift the same-signature restriction for `extern "tail"`) - #158242 (Fix linking for wasm with crate metadata included) - #158119 (Refactor `proc_macro_decls_static`) - #158172 (update `asm_experimental_reg` comments) - #158230 (Include `Item::stability` info in rustdoc JSON.) - #158258 (Use an unexpanded span for actually written down opt out params) - #158262 (Change compiler leads in triagebot.toml)
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…uwer Rollup of 8 pull requests Successful merges: - #158242 (Fix linking for wasm with crate metadata included) - #157978 (Avoid `&raw` recovery ICE after trailing comma) - #158119 (Refactor `proc_macro_decls_static`) - #158171 (rustdoc: Avoid ICE on unevaluated `type const` projections in array lengths) - #158172 (update `asm_experimental_reg` comments) - #158230 (Include `Item::stability` info in rustdoc JSON.) - #158258 (Use an unexpanded span for actually written down opt out params) - #158262 (Change compiler leads in triagebot.toml)
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…uwer Rollup of 8 pull requests Successful merges: - #158242 (Fix linking for wasm with crate metadata included) - #157978 (Avoid `&raw` recovery ICE after trailing comma) - #158119 (Refactor `proc_macro_decls_static`) - #158171 (rustdoc: Avoid ICE on unevaluated `type const` projections in array lengths) - #158172 (update `asm_experimental_reg` comments) - #158230 (Include `Item::stability` info in rustdoc JSON.) - #158258 (Use an unexpanded span for actually written down opt out params) - #158262 (Change compiler leads in triagebot.toml)
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…uwer Rollup of 8 pull requests Successful merges: - #158242 (Fix linking for wasm with crate metadata included) - #157978 (Avoid `&raw` recovery ICE after trailing comma) - #158119 (Refactor `proc_macro_decls_static`) - #158171 (rustdoc: Avoid ICE on unevaluated `type const` projections in array lengths) - #158172 (update `asm_experimental_reg` comments) - #158230 (Include `Item::stability` info in rustdoc JSON.) - #158258 (Use an unexpanded span for actually written down opt out params) - #158262 (Change compiler leads in triagebot.toml)
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…uwer Rollup of 8 pull requests Successful merges: - #158242 (Fix linking for wasm with crate metadata included) - #157978 (Avoid `&raw` recovery ICE after trailing comma) - #158119 (Refactor `proc_macro_decls_static`) - #158171 (rustdoc: Avoid ICE on unevaluated `type const` projections in array lengths) - #158172 (update `asm_experimental_reg` comments) - #158230 (Include `Item::stability` info in rustdoc JSON.) - #158258 (Use an unexpanded span for actually written down opt out params) - #158262 (Change compiler leads in triagebot.toml)
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Rollup merge of #158242 - bjorn3:wasm_rust_dylib_metadata, r=Mark-Simulacrum Fix linking for wasm with crate metadata included On wasm the crate metadata ends up in a custom section. It is not possible to refer to create symbols inside a custom section, so attempting to export it during linking will result in a linker error. This keeps the target spec flag to deny compiling rust dylibs for wasm, but may theoretically allow compiling wasm rust dylibs with a custom target spec. It will help with wasm proc-macros. And in the future we can try to flip the only-cdylib option to false on wasm. Extracted out of #157709, but also helps with #157590. r? @Mark-Simulacrum
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On wasm the crate metadata ends up in a custom section. It is not possible to refer to create symbols inside a custom section, so attempting to export it during linking will result in a linker error. This keeps the target spec flag to deny compiling rust dylibs for wasm, but may theoretically allow compiling wasm rust dylibs with a custom target spec. It will help with wasm proc-macros. And in the future we can try to flip the only-cdylib option to false on wasm.
Extracted out of #157709, but also helps with #157590.
r? @Mark-Simulacrum