rust-lang/cargo · error · anyhow::Error

`lints.{tool}.{name}` is not a valid lint name

Error message

`lints.{tool}.{name}` is not a valid lint name

What it means

Thrown during lint-table validation at src/workspace/parser/mod.rs:2735 — the catch-all for a lint name that contains `::` but matches neither of the recoverable cases (prefix != tool, and not a supported-tool re-home). Cargo cannot map the qualified name to any known lint group, so it rejects it as simply "not a valid lint name".

Source

Thrown at src/workspace/parser/mod.rs:2735

            }
            if let Some(existing) = seen_normalized.get(&normalized) {
                warnings.push(format!(
                    "duplicate lint `{existing}` in `[lints.{tool}]`, \
                     conflicts with `{name}` and will not work in a future edition"
                ));
            }
            seen_normalized.insert(normalized.clone(), name.to_string());
            if let Some((prefix, suffix)) = name.split_once("::") {
                if tool == prefix {
                    anyhow::bail!(
                        "`lints.{tool}.{name}` is not valid lint name; try `lints.{prefix}.{suffix}`"
                    )
                } else if tool == "rust" && supported.contains(&prefix) {
                    anyhow::bail!(
                        "`lints.{tool}.{name}` is not valid lint name; try `lints.{prefix}.{suffix}`"
                    )
                } else {
                    anyhow::bail!("`lints.{tool}.{name}` is not a valid lint name")
                }
            } else if let Some(config) = config.config() {
                for config_name in config.keys() {
                    // manually report unused manifest key warning since we collect all the "extra"
                    // keys and values inside the config table
                    let expected = EXPECTED_LINT_CONFIG.contains(&(tool, name, config_name));
                    if !expected {
                        let message =
                            format!("unused manifest key: `lints.{tool}.{name}.{config_name}`");
                        warnings.push(message);
                    }
                }
            }
        }
    }

    Ok(())
}

View on GitHub (pinned to 0e07a15537)

Solutions

1. Use the bare, real lint name for the tool: `[lints.rust] bar = "warn"`.
2. Confirm the lint exists via `rustc -W help` / clippy docs and which tool table it belongs to.
3. Drop any unsupported `::` qualifier.

Example fix

# before
[lints.rust]
foo::bar = "warn"
# after
[lints.rust]
bar = "warn"

for (name, _) in lints_for_tool {
    if name.contains("::") {
        return Err(format!("{name} is not a valid lint name for [lints.{tool}]"));
    }
}

When it happens

Trigger: A lint key like `[lints.rust] foo::bar = "warn"` where `foo` is neither the tool nor a supported tool (e.g. an arbitrary group or typo).

Common situations: Typos in lint names; using clippy-style group names under the wrong tool; inventing qualified names that don't exist.

Related errors

• `lints.{tool}.{name}` is not valid lint name; try `lints.{pr
• the crate `{}` depends on crate `{}` multiple times with dif
• Use of `default_features` in `{key}` is unsupported, please
• cannot override `workspace.lints` in `lints`, either remove
• `{old_path}` is unsupported as of the 2024 edition; instead

AI-assisted analysis of rust-lang/cargo@0e07a15537 (2026-08-06). Data as JSON: /data/errors/45ee40860e16f1ee.json. Report an issue: GitHub.