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adds better error message for temporary value does not live long enough - #154810

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Hiryxx:fix-inline-const-e0492
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adds better error message for temporary value does not live long enough#154810
Hiryxx wants to merge 4 commits into
rust-lang:mainfrom
Hiryxx:fix-inline-const-e0492

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@Hiryxx Hiryxx commented Apr 4, 2026 •
edited by rustbot
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When &const { expr } is borrowed for 'static but expr has interior mutability (is not Freeze), emit E0492 instead
of E0716

Closes #154382

@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Apr 4, 2026
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r? @JohnTitor

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JohnTitor
JohnTitor reviewed Apr 9, 2026
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Comment thread compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs Outdated
Comment thread tests/ui/inline-const/interior-mutable-borrow.rs Outdated
Comment thread compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs Outdated
@JohnTitor JohnTitor added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Apr 9, 2026
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Hiryxx requested a review from JohnTitor April 14, 2026 14:02
@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Apr 14, 2026
JohnTitor
JohnTitor reviewed May 29, 2026
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Comment thread compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs Outdated
@JohnTitor JohnTitor added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels May 29, 2026
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rustbot commented Jun 26, 2026

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Some changes occurred to the CTFE machinery

cc @RalfJung, @oli-obk, @lcnr

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@Hiryxx
Hiryxx force-pushed the fix-inline-const-e0492 branch from 089360f to a91dbb5 Compare June 26, 2026 13:38
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rustbot commented Jun 26, 2026

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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.

@Hiryxx
Hiryxx requested a review from JohnTitor June 26, 2026 15:19
@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jun 26, 2026
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Hiryxx commented Jun 26, 2026

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I had to pull the detection into a span variable up top and reuse it as a flag, this makes it a little verbose for the error output but I couldn't find a better since the alternatives where worse. Let me know what you think @JohnTitor.

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rust-bors Bot commented Jul 12, 2026

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☔ The latest upstream changes (presumably #159170) made this pull request unmergeable. Please resolve the merge conflicts by rebasing.

JohnTitor
JohnTitor reviewed Jul 31, 2026
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Comment thread compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
let borrowed_ty = self.body.local_decls[borrow.borrowed_place.local].ty;
let typing_env = self.infcx.typing_env(self.infcx.param_env);
let tcx = self.infcx.tcx;
if !borrowed_ty.is_freeze(tcx, typing_env) {

@JohnTitor JohnTitor Jul 31, 2026 •
edited by rustbot
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Checking interior mutability with !Freeze can be false-positive, it isn't equal that promotion failure is due to it.
Maybe we should use the existing mechanism like https://doc.rust-lang.org/nightly/nightly-rustc/rustc_const_eval/check_consts/qualifs/struct.HasMutInterior.html to harden the checker.

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@JohnTitor

JohnTitor commented Jul 31, 2026

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I had to pull the detection into a span variable up top and reuse it as a flag, this makes it a little verbose for the error output but I couldn't find a better since the alternatives where worse. Let me know what you think @JohnTitor.

I think the current is fine 👍

@JohnTitor JohnTitor removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jul 31, 2026
@JohnTitor JohnTitor added the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Jul 31, 2026
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Confusing error when trying to promote a const to a static item

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