Recommend to never display zero disambiguators when demangling v0 symbols #124514
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rustbot has assigned @GuillaumeGomez. Use |
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cc @ehuss, as the original author of these (incredible) docs. |
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r? eddyb |
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@eddyb, would you like me to make any changes to this PR before it can be approved? |
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@_eddyb seems to be unavailable at the moment. r? @davidtwco maybe? |
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@bors r+ rollup |
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…kingjubilee Rollup of 16 pull requests Successful merges: - rust-lang#123374 (DOC: Add FFI example for slice::from_raw_parts()) - rust-lang#124514 (Recommend to never display zero disambiguators when demangling v0 symbols) - rust-lang#125978 (Cleanup: HIR ty lowering: Consolidate the places that do assoc item probing & access checking) - rust-lang#125980 (Nvptx remove direct passmode) - rust-lang#126187 (For E0277 suggest adding `Result` return type for function when using QuestionMark `?` in the body.) - rust-lang#126210 (docs(core): make more const_ptr doctests assert instead of printing) - rust-lang#126249 (Simplify `[T; N]::try_map` signature) - rust-lang#126256 (Add {{target}} substitution to compiletest) - rust-lang#126263 (Make issue-122805.rs big endian compatible) - rust-lang#126281 (set_env: State the conclusion upfront) - rust-lang#126286 (Make `storage-live.rs` robust against rustc internal changes.) - rust-lang#126287 (Update a cranelift patch file for formatting changes.) - rust-lang#126301 (Use `tidy` to sort crate attributes for all compiler crates.) - rust-lang#126305 (Make PathBuf less Ok with adding UTF-16 then `into_string`) - rust-lang#126310 (Migrate run make prefer rlib) - rust-lang#126314 (fix RELEASES: we do not support upcasting to auto traits) r? `@ghost` `@rustbot` modify labels: rollup
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Rollup merge of rust-lang#124514 - michaelwoerister:zero-disambiguator-demangling-recommendation, r=davidtwco Recommend to never display zero disambiguators when demangling v0 symbols This PR extends the [v0 symbol mangling documentation](https://doc.rust-lang.org/rustc/symbol-mangling/v0.html) with the strong recommendation that demanglers should never display zero-disambiguators, especially when dealing with `crate-root`. Being able to rely on `C3foo` to be rendered as `foo` (i.e. without explicit disambiguator value) rather than as `foo[0]` allows the compiler to encode things like new basic types in a backward compatible way. This idea has been originally proposed by `@eddyb` in [the discussion around supporting `f16` and `f128` in the v0 mangling scheme](rust-lang#122106). It is a generally useful mechanism for supporting a certain class of new elements in the v0 mangling scheme in a backward compatible way (whether as a temporary workaround until downstream tooling has picked up grammar changes or as a permanent encoding). cc `@tgross35`
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…kingjubilee Rollup of 16 pull requests Successful merges: - rust-lang#123374 (DOC: Add FFI example for slice::from_raw_parts()) - rust-lang#124514 (Recommend to never display zero disambiguators when demangling v0 symbols) - rust-lang#125978 (Cleanup: HIR ty lowering: Consolidate the places that do assoc item probing & access checking) - rust-lang#125980 (Nvptx remove direct passmode) - rust-lang#126187 (For E0277 suggest adding `Result` return type for function when using QuestionMark `?` in the body.) - rust-lang#126210 (docs(core): make more const_ptr doctests assert instead of printing) - rust-lang#126249 (Simplify `[T; N]::try_map` signature) - rust-lang#126256 (Add {{target}} substitution to compiletest) - rust-lang#126263 (Make issue-122805.rs big endian compatible) - rust-lang#126281 (set_env: State the conclusion upfront) - rust-lang#126286 (Make `storage-live.rs` robust against rustc internal changes.) - rust-lang#126287 (Update a cranelift patch file for formatting changes.) - rust-lang#126301 (Use `tidy` to sort crate attributes for all compiler crates.) - rust-lang#126305 (Make PathBuf less Ok with adding UTF-16 then `into_string`) - rust-lang#126310 (Migrate run make prefer rlib) - rust-lang#126314 (fix RELEASES: we do not support upcasting to auto traits) r? `@ghost` `@rustbot` modify labels: rollup
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This PR extends the v0 symbol mangling documentation with the strong recommendation that demanglers should never display zero-disambiguators, especially when dealing with
crate-root.Being able to rely on
C3footo be rendered asfoo(i.e. without explicit disambiguator value) rather than asfoo[0]allows the compiler to encode things like new basic types in a backward compatible way. This idea has been originally proposed by @eddyb in the discussion around supportingf16andf128in the v0 mangling scheme. It is a generally useful mechanism for supporting a certain class of new elements in the v0 mangling scheme in a backward compatible way (whether as a temporary workaround until downstream tooling has picked up grammar changes or as a permanent encoding).cc @tgross35