Check closure's constness validity in the constness query#155772
Check closure's constness validity in the constness query#155772oli-obk wants to merge 2 commits intorust-lang:mainfrom
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| LL | (const || { (()).foo() })(); | ||
| | ^^^^^ | ||
| | ^^^^^^^^ |
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The only downside of this PR is that we highlight more than the const part of the closure now
| Node::Expr(e) if let ExprKind::Closure(c) = e.kind => { | ||
| match c.constness { | ||
| Constness::Const => if tcx.hir_body_const_context(tcx.local_parent(def_id)).is_none() { | ||
| tcx.dcx().span_err(tcx.def_span(def_id), "cannot use `const` closures outside of const contexts"); |
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A hacky way could be to use https://doc.rust-lang.org/stable/nightly-rustc/rustc_span/source_map/struct.SourceMap.html#method.span_until_whitespace since we always know that const is the first keyword (for now).
But this is not necessary
| match c.constness { | ||
| Constness::Const => if tcx.hir_body_const_context(tcx.local_parent(def_id)).is_none() { |
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I would use if let Constness::Const = c.constness && tcx.hir_body_const_context(tcx.local_parent(def_id)).is_none() here
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@bors r=fee1-dead rollup |
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instead of during ast lowering, where it's not easily possible to obtain all the right information in time
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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. |
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@bors r=fee1-dead rollup |
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… r=fee1-dead Check closure's constness validity in the constness query fixes rust-lang#155584 instead of checking during ast lowering, where it's not easily possible to obtain all the right information in time. While lowering an assoc item we don't know if the parent was a const trait or a const impl. Tracing this information is quite annoying, and complicates a lot of code, which checking here after the fact is trivial.
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This pull request was unapproved. This PR was contained in a rollup (#155791), which was unapproved. |
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fixes #155584
instead of checking during ast lowering, where it's not easily possible to obtain all the right information in time. While lowering an assoc item we don't know if the parent was a const trait or a const impl. Tracing this information is quite annoying, and complicates a lot of code, which checking here after the fact is trivial.