Configuration basics#

Where configuration lives#

Configuration goes in Cargo.toml metadata tables. There are two scopes:

• Package — [package.metadata.cargo-fc], in a crate’s Cargo.toml. Shapes that package’s feature matrix.
• Workspace — [workspace.metadata.cargo-fc], in the workspace root Cargo.toml. Applies across the workspace (package selection, targets, flag defaults).

# crate Cargo.toml
[package.metadata.cargo-fc]
exclude_features = ["default"]

# workspace root Cargo.toml
[workspace.metadata.cargo-fc]
exclude_packages = ["examples"]

Excluding workspace packages#

Remove packages from every run in the workspace metadata:

[workspace.metadata.cargo-fc]
exclude_packages = ["package-a", "package-b"]

Package exclusion is a workspace-level decision — a package can’t exclude its siblings.

What can be configured where#

Not every setting is meaningful in every scope. The feature-matrix keys, for instance, only make sense on a package, because a workspace has no features of its own. The full picture is the override model; the short version:

Each of these can be refined further by target and by command — that’s what the rest of this section covers.

A first example#

[package.metadata.cargo-fc]
# Don't vary `default`; it's implied by everything anyway.
exclude_features = ["default"]

# These two features are mutually exclusive.
exclude_feature_sets = [["postgres", "sqlite"]]

# Ignore implicit features created for optional dependencies.
skip_optional_dependencies = true

Next: shaping the feature matrix.