cargo-report

Show future incompatibility report

$ cargo report future-incompatibilities --id [1]

$ cargo build --future-incompat-report

cargo report type [options]

cargo report generates diagnostic reports about the project. Currently its primary subcommand is `future-incompatibilities`, which displays warnings about code patterns in dependencies that will be rejected in future Rust versions.
When Cargo detects future-incompatible warnings during a build, it stores a report and displays a notification with instructions to view the full details. These warnings indicate patterns that may exhibit undefined behavior, are scheduled for removal, or lack well-defined semantics. Reviewing these reports helps maintainers proactively update their dependencies before breaking changes land.

--id id

Report ID from previous build

Package to report on

Verbose output

Suppress output

.cargo/config.toml

Controls report frequency via `[future-incompat-report]` section (e.g., `frequency = "always"`).

future-incompatibilities

Display future incompatibility report

Cargo checks dependencies for patterns that:
- May exhibit undefined behavior
- Are scheduled for removal from Rust
- Do not have well-defined semantics
When detected, a warning appears after build with instructions to view the full report.

1. Update dependencies to versions with fixes
2. Work with dependency maintainers
3. Consider alternatives if unmaintained

Report is not a lint and doesn't interact with -Dwarnings. These warnings don't fail builds but indicate future breakage.

cargo(1), cargo-build(1)