Inconsistent definitions for lib.name regarding hyphens

[dvdhrm]

Currently, Cargo refuses values with hyphens or special characters in lib.name, but uses the package-name as default value, if unspecified. The package-name can contain hyphens, though. This leads to inconsistent behavior, where lib.name ends up with special characters, yet Cargo refuses specifying such values directly in the manifest.

Cargo documentation states that the default value is the package-name, but any special characters replaced by underscores. Unfortunately, Cargo never implemented this transformation, thus leading to the inconsistent behavior.

PR #12640 tried to change Cargo to allow any value as lib.name (aligning library targets with all other targets). After discussion, the recommended approach is to instead align Cargo with its documentation and actually transforming the package-name to a valid lib.name.

Related issue: #11259