make invalid_value lint a bit smarter around enums #102281
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compiler/rustc_lint/src/builtin.rs
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| let existing_variants = adt.variants().iter().filter(|v| v.fields.is_empty()).count(); | ||
| existing_variants > 1 | ||
| /// Determines whether the given type is inhabited. `None` means that we don't know. | ||
| fn ty_inhabited(ty: Ty<'_>) -> Option<bool> { |
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Why not use tcx.type_uninhabited_from?
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Good question. Unfortunately the documentation is not helpful:
Computes the set of modules from which this type is visibly uninhabited. To check whether a type is uninhabited at all (not just from a given module), you could check whether the forest is empty.
Now I still don't know if this is an underapproximation or an overapproximation -- is this "definitely uninhabited" or "maybe uninhabited"? No idea which forest it is talking about.^^ 🌲
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type_uninhabited_from means definitely uninhabited. References and arrays of unknown length are considered inhabited by this query.
The "forest" is the query's return type, I agree this is esoteric. tcx.type_uninhabited_from(param_env.and(ty)).is_empty() means that ty is possibly inhabited (opposite of definitely uninhabited).
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Looks like I can use is_ty_uninhabited_from as a nice wrapper.
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and no then I need a module to check 'from'...
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…iaskrgr Rollup of 9 pull requests Successful merges: - rust-lang#101555 (Stabilize `#![feature(mixed_integer_ops)]`) - rust-lang#102253 (rustdoc: use CSS containment to speed up render) - rust-lang#102281 (make invalid_value lint a bit smarter around enums) - rust-lang#102284 (Structured suggestion for missing `mut`/`const` in raw pointer) - rust-lang#102330 (rustdoc: remove no-op CSS `.srclink { font-weight; font-size }`) - rust-lang#102337 (Avoid LLVM-deprecated `Optional::hasValue`) - rust-lang#102356 (session: remove now-unnecessary lint `#[allow]`s) - rust-lang#102367 (rustdoc: remove redundant `#help-button` CSS) - rust-lang#102369 (Fix search result colors) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup
Fixes #102043