Crate rustc_feature

Feature gates

This crate declares the set of past and present unstable features in the compiler. Feature gate checking itself is done in rustc_ast_passes/src/feature_gate.rs at the moment.

Features are enabled in programs via the crate-level attributes of #![feature(...)] with a comma-separated list of features.

For the purpose of future feature-tracking, once a feature gate is added, even if it is stabilized or removed, do not remove it. Instead, move the symbol to the accepted or removed modules respectively.

Modules

• accepted 🔒
  List of the accepted feature gates.
• active 🔒
  List of the active feature gates.
• builtin_attrs 🔒
  Built-in attributes and cfg flag gating.
• removed 🔒
  List of the removed feature gates.

Structs

• AttributeTemplate
  A template that the attribute input must match. Only top-level shape (#[attr] vs #[attr(...)] vs #[attr = ...]) is considered now.
• BuiltinAttribute
• Feature
• Features
  A set of features to be used by later passes.

Enums

• AttributeDuplicates
  How to handle multiple duplicate attributes on the same item.
• AttributeGate
• AttributeType
• GateIssue
• Stability
• State
• UnstableFeatures

Constants

• ACCEPTED_FEATURES
  Those language feature has since been Accepted (it was once Active)
• ACTIVE_FEATURES
  Represents active features that are currently being implemented or currently being considered for addition/removal.
• BUILTIN_ATTRIBUTES
  Attributes that have a special meaning to rustc or rustdoc.
• INCOMPATIBLE_FEATURES
  Some features are not allowed to be used together at the same time, if the two are present, produce an error.
• REMOVED_FEATURES
  Represents unstable features which have since been removed (it was once Active)
• STABLE_REMOVED_FEATURES
  Represents stable features which have since been removed (it was once Accepted)

Statics

• BUILTIN_ATTRIBUTE_MAP

Functions

• deprecated_attributes
• find_feature_issue
• find_gated_cfg
  Find a gated cfg determined by the predicate which is given the cfg’s name.
• find_lang_feature_issue 🔒
• is_builtin_attr_name
• is_builtin_only_local
  Whether this builtin attribute is only used in the local crate. If so, it is not encoded in the crate metadata.
• is_valid_for_get_attr
• to_nonzero 🔒

Type Aliases

• GatedCfg