Module guppy::platform

Support for dependencies that are only enabled on some platforms.

Most of the time, dependencies are enabled across all platforms. For example, in this Cargo.toml:

# once_cell 1.5 is enabled on all platforms.
[dependencies]
once_cell = "1.5"

However, in some cases, dependencies may only be enabled on certain platforms.

# This dependency is only enabled on Linux x86_64.
[target.x86_64-unknown-linux-gnu.dependencies]
inotify = "0.9.4"

# This build dependency is enabled on Windows.
[target.'cfg(windows)'.build-dependencies]
winapi = "0.3.9"

This module provides types that can represent platforms and evaluate expressions.

Representing platforms

• Platform represents a single platform.
• Triple is a Rust target triple.
• PlatformSpec represents a single platform or a range of platforms, including any platform (the union of all possible platforms) and all platforms (the intersection of all possible platforms).

Evaluating platforms

These structs are defined in the context of a PackageGraph, and are typically returned through PackageLink instances.

• PlatformStatus: The status of a dependency or a feature which might be platform-dependent.
• PlatformEval: A collection of platform specifications like cfg(unix), to evaluate against a platform.
• EnabledTernary: A three-valued logic representing the status of a dependency or feature on a given platform. Includes an additional status to represent situations like unknown target features.

If the summaries feature is enabled, this module also supports reading and writing serializable summaries of platforms. These can be used both as configuration, and to serialize the results of a particular guppy evaluation.

For more, about platform-specific dependencies, see Platform specific dependencies in the Cargo reference.

Structs

• Platform
  A platform to evaluate target specifications against.
• PlatformEval
  An evaluator for platform-specific dependencies.
• Triple
  A single, specific target, uniquely identified by a triple.

Enums

• EnabledTernary
  Whether a dependency or feature is enabled on a specific platform.
• PlatformSpec
  A specifier for a single platform, or for a range of platforms.
• PlatformStatus
  The status of a dependency or feature, which is possibly platform-dependent.
• TargetFeatures
  A set of target features to match.