CanonicalPackageLocation

A package may declare external packages as dependencies in its manifest. Each external package is uniquely identified by the location of its source code.

An external package dependency may itself have one or more external package dependencies, known as transitive dependencies. When multiple packages have dependencies in common, Swift Package Manager determines which version of that package should be used (if any exist that satisfy all specified requirements) in a process called package resolution.

External package dependencies are located by a URL (which may be an implicit file:// URL in the form of a file path). For the purposes of package resolution, package URLs are case-insensitive (mona ≍ MONA) and normalization-insensitive (n + ◌̃ ≍ ñ). Swift Package Manager takes additional steps to canonicalize URLs to resolve insignificant differences between URLs. For example, the URLs https://example.com/Mona/LinkedList and git@example.com:mona/linkedlist are equivalent, in that they both resolve to the same source code repository, despite having different scheme, authority, and path components.

The PackageIdentity type canonicalizes package locations by performing the following operations:

• Removing the scheme component, if present

  https://example.com/mona/LinkedList → example.com/mona/LinkedList

• Removing the userinfo component (preceded by @), if present:

  git@example.com/mona/LinkedList → example.com/mona/LinkedList

• Removing the port subcomponent, if present:

  example.com:443/mona/LinkedList → example.com/mona/LinkedList

• Replacing the colon (:) preceding the path component in “scp-style” URLs:

  git@example.com:mona/LinkedList.git → example.com/mona/LinkedList

• Expanding the tilde (~) to the provided user, if applicable:

  ssh://mona@example.com/~/LinkedList.git → example.com/~mona/LinkedList

• Removing percent-encoding from the path component, if applicable:

  example.com/mona/%F0%9F%94%97List → example.com/mona/🔗List

• Removing the .git file extension from the path component, if present:

  example.com/mona/LinkedList.git → example.com/mona/LinkedList

• Removing the trailing slash (/) in the path component, if present:

  example.com/mona/LinkedList/ → example.com/mona/LinkedList

• Removing the fragment component (preceded by #), if present:

  example.com/mona/LinkedList#installation → example.com/mona/LinkedList

• Removing the query component (preceded by ?), if present:

  example.com/mona/LinkedList?utm_source=forums.swift.org → example.com/mona/LinkedList

• Adding a leading slash (/) for file:// URLs and absolute file paths:

  file:///Users/mona/LinkedList → /Users/mona/LinkedList