Semantic check of mut restrictions - #159906
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Some changes occurred to MIR optimizations cc @rust-lang/wg-mir-opt |
mut restrictions
Urgau
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Jul 25, 2026
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| // MIR-level lints. | ||
| &Lint(check_inline::CheckForceInline), | ||
| &Lint(check_call_recursion::CheckCallRecursion), | ||
| &Lint(check_packed_ref::CheckPackedRef), | ||
| &Lint(check_const_item_mutation::CheckConstItemMutation), | ||
| &Lint(check_mut_restriction::CheckMutRestriction), | ||
| &Lint(function_item_references::FunctionItemReferences), |
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(Not for this PR) Most of those so called "MIR lints" actually emit hard errors of an lint. We should find another name as it's quite confusing to see a "lint" emit a hard errors.
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| fn change_fooe(foo: &mut foo::bar::FooE) { | ||
| match foo { | ||
| foo::bar::FooE::Default => {} | ||
| foo::bar::FooE::Var { | ||
| alpha, //[e2015]~ ERROR field cannot be mutated outside `foo::bar` | ||
| //[e2018]~^ ERROR field cannot be mutated outside `crate::foo::bar` | ||
| beta, //[e2015]~ ERROR field cannot be mutated outside `foo` | ||
| //[e2018]~^ ERROR field cannot be mutated outside `crate::foo` | ||
| gamma, // ok | ||
| } => { | ||
| *alpha = 1; | ||
| *beta = 1; | ||
| *gamma = 1; | ||
| } | ||
| foo::bar::FooE::Tup( | ||
| alpha, //[e2015]~ ERROR field cannot be mutated outside `foo::bar` | ||
| //[e2018]~^ ERROR field cannot be mutated outside `crate::foo::bar` | ||
| beta, //[e2015]~ ERROR field cannot be mutated outside `foo` | ||
| //[e2018]~^ ERROR field cannot be mutated outside `crate::foo` | ||
| gamma, // ok | ||
| ) => { | ||
| *alpha = 1; | ||
| *beta = 1; | ||
| *gamma = 1; | ||
| } | ||
| } | ||
| } |
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@Nadrieril, can you think of another match related tests we should be testing regarding mut-restrictions?
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cc @cjgillot for the MIR related part since you know more about it than me |
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@rustbot ready |
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Urgau
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Jul 29, 2026
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I was just thinking of something, we should probably remove the incompleteness of the feature. |
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This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed. Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers. |
jhpratt
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August 1, 2026 08:04
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I'll review this PR this weekend. |
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Squashed the commits, and removed the incompleteness marker. |
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This PR implements semantic checks for
mutrestrictions proposed in RFC 3323, as part of the related GSoC project.It lowers field restriction information from HIR into
rustc_middle::ty::FieldDefand adds a MIR-level lint that rejects restricted field mutations and struct expressions. As parsing (#156824) and path resolution (#159125) have already been implemented, this PR provides a working implementation ofmutrestrictions.Tracking issue: #105077
r? @Urgau
cc @jhpratt