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future incompatibility warning on nightly-2026-08-12 (1.99) #33

Description

@tguichaoua

Bug report

When building a project using const-decoder@0.4 on nightly-2026-08-12 (1.99) I got this warning from the compiler:

The package `const-decoder v0.4.0` currently triggers the following future incompatibility lints:
> warning: trailing semicolon in macro used in expression position
>    --> \.cargo\registry\src\index.crates.io-1949cf8c6b5b557f\const-decoder-0.4.0\src\decoder.rs:102:22
>     |
> 102 |               other => compile_panic!(
>     |  ______________________^
> 103 | |                 "Invalid alphabet length ", other => fmt::<usize>(),
> 104 | |                 "; must be one of 2, 4, 8, 16, 32, or 64"
> 105 | |             ),
>     | |_____________^
>     |
>     = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
>     = note: for more information, see issue #79813 <https://github.com/rust-lang/rust/issues/79813>
>     = note: this warning originates in the macro `compile_panic` (in Nightly builds, run with -Z macro-backtrace for more info)
>

Steps to reproduce

  1. add const-decoder = "0.4" in Cargo.toml
  2. run cargo +nightly-2026-08-12 build --future-incompat-report

Expected behavior

No warnings

Environment

  • Rust: nightly-2026-08-12

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