interpret: go back to regular string interpolation for error messages by RalfJung · Pull Request #153611 · rust-lang/rust

RalfJung · 2026-03-09T14:36:56Z

Using the translatable diagnostic infrastructure adds a whole lot of boilerplate which isn't actually useful for const-eval errors, so let's get rid of it. This effectively reverts #111677. That PR effectively added 1000 lines and this PR only removes around 600 -- the difference is caused by (a) keeping some of the types around for validation, where we can use them to share error strings and to trigger the extra help for pointer byte shenanigans during CTFE, and (b) this not being a full revert of #111677; I am not touching diagnostics outside the interpreter such as all the const-checking code which also got converted to fluent in the same PR.

The last commit does something similar for LayoutError, which also helps deduplicate a bunch of error strings. I can make that into a separate PR if you prefer.

r? @oli-obk
Fixes #113117
Fixes #116764
Fixes #112618

rustbot · 2026-03-09T14:37:02Z

Some changes occurred to the CTFE / Miri interpreter

cc @rust-lang/miri

The Miri subtree was changed

cc @rust-lang/miri

Some changes occurred to the CTFE machinery

cc @oli-obk, @lcnr

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

Some changes occurred to the CTFE / Miri interpreter

cc @rust-lang/miri, @oli-obk, @lcnr

rustbot · 2026-03-09T14:37:06Z

oli-obk is not on the review rotation at the moment.
They may take a while to respond.

Bryntet · 2026-03-09T14:55:06Z

compiler/rustc_abi/src/lib.rs

-            AlignFromBytesError::NotPowerOfTwo(align) => write!(f, "`{align}` is not a power of 2"),
-            AlignFromBytesError::TooLarge(align) => write!(f, "`{align}` is too large"),


I personally prefer this with the backticks

These are just numbers. We don't usually render them with backticks. And in fact they were not rendered with backticks in const-eval errors before, only in JSON errors. I changed the strings here to avoid changing the const-eval error output.

RalfJung · 2026-03-09T15:19:46Z

compiler/rustc_abi/src/lib.rs

    TooLarge(u64),
 }

-impl AlignFromBytesError {


The AlignFromBytesError type got added #111677. Reverting that PR would mean replacing it by String again, but it actually seems reasonable to have a proper error type here so I decided to keep the type, but simplify and deduplicate the logic for turning it into a user-visible message.

rustbot · 2026-03-09T16:54:37Z

Some changes occurred in compiler/rustc_codegen_gcc

cc @antoyo, @GuillaumeGomez

GuillaumeGomez · 2026-03-09T16:58:10Z

This is MUCH better, thanks a lot!

oli-obk

@bors r+

View changes since this review

rust-bors · 2026-03-11T08:20:11Z

📌 Commit e50b65c has been approved by oli-obk

It is now in the queue for this repository.

rustbot · 2026-03-11T12:55:16Z

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.

RalfJung · 2026-03-11T13:17:45Z

@bors r=oli-obk

rust-bors · 2026-03-11T13:17:48Z

📌 Commit fe1f92a has been approved by oli-obk

It is now in the queue for this repository.

@oli-obk

…li-obk interpret: go back to regular string interpolation for error messages Using the translatable diagnostic infrastructure adds a whole lot of boilerplate which isn't actually useful for const-eval errors, so let's get rid of it. This effectively reverts rust-lang#111677. That PR effectively added 1000 lines and this PR only removes around 600 -- the difference is caused by (a) keeping some of the types around for validation, where we can use them to share error strings and to trigger the extra help for pointer byte shenanigans during CTFE, and (b) this not being a full revert of rust-lang#111677; I am not touching diagnostics outside the interpreter such as all the const-checking code which also got converted to fluent in the same PR. The last commit does something similar for `LayoutError`, which also helps deduplicate a bunch of error strings. I can make that into a separate PR if you prefer. r? @oli-obk Fixes rust-lang#113117 Fixes rust-lang#116764 Fixes rust-lang#112618

…uwer Rollup of 9 pull requests Successful merges: - #153571 (Avoid ICE when an EII declaration conflicts with a constructor) - #153581 (Simplify `type_of_opaque`.) - #153611 (interpret: go back to regular string interpolation for error messages) - #153635 (Unify same-span labels in move error diagnostics) - #153660 (mir-opt: Drop invalid debuginfos after SingleUseConsts.) - #153685 (Introduce `for_each_query_vtable!` to move more code out of query macros) - #153671 (Make Enzyme has dependent on LLVM hash) - #153710 (remove `.ftl` checks from tidy) - #153720 (doc/rustc: clarify how to contact arm-maintainers)

…uwer Rollup of 12 pull requests Successful merges: - #152569 (Stop using rustc_layout_scalar_valid_range_* in rustc) - #153421 (Fix ICE in fn_delegation when child segment resolves to a trait) - #153571 (Avoid ICE when an EII declaration conflicts with a constructor) - #153581 (Simplify `type_of_opaque`.) - #153611 (interpret: go back to regular string interpolation for error messages) - #153635 (Unify same-span labels in move error diagnostics) - #153660 (mir-opt: Drop invalid debuginfos after SingleUseConsts.) - #153685 (Introduce `for_each_query_vtable!` to move more code out of query macros) - #153722 (miri-test-libstd: use --tests and update some comments) - #153671 (Make Enzyme has dependent on LLVM hash) - #153710 (remove `.ftl` checks from tidy) - #153720 (doc/rustc: clarify how to contact arm-maintainers)

…uwer Rollup of 12 pull requests Successful merges: - rust-lang/rust#152569 (Stop using rustc_layout_scalar_valid_range_* in rustc) - rust-lang/rust#153421 (Fix ICE in fn_delegation when child segment resolves to a trait) - rust-lang/rust#153571 (Avoid ICE when an EII declaration conflicts with a constructor) - rust-lang/rust#153581 (Simplify `type_of_opaque`.) - rust-lang/rust#153611 (interpret: go back to regular string interpolation for error messages) - rust-lang/rust#153635 (Unify same-span labels in move error diagnostics) - rust-lang/rust#153660 (mir-opt: Drop invalid debuginfos after SingleUseConsts.) - rust-lang/rust#153685 (Introduce `for_each_query_vtable!` to move more code out of query macros) - rust-lang/rust#153722 (miri-test-libstd: use --tests and update some comments) - rust-lang/rust#153671 (Make Enzyme has dependent on LLVM hash) - rust-lang/rust#153710 (remove `.ftl` checks from tidy) - rust-lang/rust#153720 (doc/rustc: clarify how to contact arm-maintainers)

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 Mar 9, 2026

rustbot assigned oli-obk Mar 9, 2026

RalfJung force-pushed the interp-error-strings branch from caa7de3 to d42a68b Compare March 9, 2026 14:38